NOAA Technical Report NMFS 15

Chaetognatha of the

Caribbean Sea and

Adjacent Areas

Harding B. Michel

October 1984

u.s. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service
NOAA TECHNICAL REPORTS NMFS

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Springfield, VA 22161.
NOAA Technical Report NMFS 15

Chaetognatha of the

Caribbean Sea and

Adjacent Areas

Harding B. Michel

October 1984

U.S. DEPARTMENT OF COMMERCE

Malcolm Baldrige, Secretary

National Oceanic and Atmospheric Administration

John V. Byrne, Administrator

National Marine Fisheries Service

William G. Gordon, Assistant Administrator for Fisheries
The National Marine Fisheries Service (NMFS) does not approve, recommend or endorse any propriety product or proprietary material mentioned

in this publication. No reference shall be made to NMFS, or to this publication furnished by NMFS, in any advertising or sales promotion which

would indicate or imply that NMFS approves, recommends or endorses any

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CONTENTS

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I

Classification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Anatomy.................... .. .. .. .. .. .. . .. .. 2

Methods..... .. .. .. .. 5

Taxonomy.............................................................................................. 6

List of species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Key to mature Chaetognatha 7

Descriptions and distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Spadella cephaloptera 10

Spadella nana 11

Spadella pulchella .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1I

Spadella schizoptera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I 3

Eukrohnia bathyantarctica ".................................. 13

Eukrohnia bathypelagica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Eukrohniafowleri 14

Eukrohnia hamata. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Eukrohnia proboscidea 16

Bathybelos typhlops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Sagitta bipunctata 17

Sagitta decipiens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Sagitta enflata 18

Sagittafriderici. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Sagitta helenae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Sagitta hexaptera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Sagitta hispida ". . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Sagitta lyra " ". . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Sagitta macrocephala . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Sagitta megalophthalma ". . . . . . . . 24

Sagitta minima. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Sagitta planctonis ". . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Sagitta planctonis forma planctonis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Sagitta planctonis forma zetesios " ". . . . . . 27

Sagitta serratodentata 27

Sagitta tenuis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Pterosagitta draco 29

Krohnitta pacifica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Krohnitta subtilis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Literature cited .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Figures

1. Locations of stations in the Caribbean Sea and adjacent regions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2. Sagitta enflata, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3. Sagitta planctonis forma zetesios, immature, ventral view of head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4. Krohnitta subtiUs, ventral view of head. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

5. Pterosagitta draco, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

6. Spadella cephaloptera, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

7. Spadella spp., dorsal views. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

8. Spadella schizoptera, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

9. Eukrohnia bathyantarctica, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

10. Eukrohnia bathypelagica, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

11. Eukrohniafowleri, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

12. Eukrohnia hamata, dorsal view .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

13. Eukrohnia proboscidea, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

14. Eukrohnia proboscidea, dorsal view of head .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

15. Eukrohniaproboscidea, ventral view of head 16

16. Bathybelos typhlops, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

17. Bathybelos typhlops, dorsal view of head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

18. Sagitta bipunctata, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

iii
19. Sagitta decipiens, dorsal view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

20. Sagitta enflata, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

21. Sagitta friderici, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

22. Sagittafriderici, ventral view of head. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

23. Sagitta helenae, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

24. Sagitta helenae, ventral view of head. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

25. Sagitta hexaptera, dorsal view 21

26. Sagitta hispida, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

27. Sagitta lyra, dorsal view .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

28. Sagitta macrocephala, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

29. Sagitta macrocephala, ventral view of head. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

30. Sagitta megalophthalma, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

31. Sagitta megalophthalma, immature, dorsal view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

32. Sagitta megalophthalma, ventral view of head. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

33. Sagitta megalophthalma, left and right eyes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

34. Sagitta minima, dorsal view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

35. Sagitta planctonis formaplanctonis, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

36. Sagitta planctonis forma zetesios, dorsal view 27

37. Sagitta serratodentata, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

38. Sagitta serratodentata, ventral view of head. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

39. Sagitta tenuis, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

40. Krohnitta pacifica, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

41. Krohnitta subtilis, dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Tables

1. Data of 25 Sagitta bipunctata from the Atlantic Ocean. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2. Summary of the vertical ranges of the more common chaetognath species in the Caribbean Sea and adjacent regions 9

3. Vertical distribution of Chaetognatha in the Caribbean Sea and adjacent regions 9

4. Previous records of chaetognath species from the Caribbean Sea, the Gulf of Mexico, the Florida Straits, and the southwestern North Atlantic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5. Measurements and counts of teeth of immature Sagitta planctonis forma zetesios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

iv
Chaetognatha of the Caribbean Sea and

Adjacent Areas

HARDING B. MICHELI

ABSTRACT

This illustrated manual is a guide to the distribution and Identification of the 6 genera and 28 species of benthic and planktonic Chaetognatha known to occur in the Caribbean Sea, the GulfofMexlco, the Florida Straits,

and the southwestern North Atlantic Ocean. As background, previous studies of chaetognaths in these areas are

reviewed, gross morphology of the different forms is described, and instructions on methods of preserving and

handling specimens preparatory to identification are provided. The key to genera and species is preceeded by a

discussion of chaetognath taxonomy. A description of each species, consisting of an abbreviated synonymy, a

summary of taxonomically important morphological features, and horizontal and vertical distribution follows

the key. The occurrence of species in relation to water masses in the Caribbean and adjacent areas Is noted.

INTRODUCTION

After Conant (1895,1896) and Ritter-Zahony (1910) pioneered in describing species from the tropical western Atlantic, almost

nothing was written about the chaetognaths in these areas until

Pierce (1951) published his work on species collected off the west

coast of Florida. Subsequently, Tokioka (1955) dealt with taxonomic problems arising from Pierce's studies, and Suarez-Caabro

(1955, 1959) published his works on the distribution of species

occurring in Cuban waters. Colman (1959) added records of

occurrence in his report on the Rosaura collections, which included vertical tows from the upper 1,000 m in the Caribbean Sea. In

1960, Owre summarized previous work in a study of the distribution of 16 species occurring in the Florida Straits off Miami, and

the deduced reproductive periods of the more numerous forms.

Legare and Zoppi (1961) reported on the abundance and distribution of 10 species from Venezuelan waters. Aivariiio (1969) tabulated the Atlantic records of 31 species and illustrated them

comprehensively.

Owre and Foyo (1971, 1972) reviewed previous investigations

of Caribbean zooplankton and, in the latter paper, discussed the

results of the first cruise in a series, sponsored by the University of

Miami, which was begun in January 1966 and was completed in

November 1969. The purpose of this series was to examine the

distribution of major groups of zooplankton in relation to water

masses in the Caribbean and adjacent areas. After the first cruise,

improved sampling procedures (Owre and Low 1969) were consistently used on the nine subsequent cruises, the results of which

were presented by H. B. Michel (formerly Owre), M. Foyo, and D.

A. Haagensen (1976). The locations of stations at which horizontal plankton tows were made at several depths between surface

and bottom are shown in Figure I.

Investigations by Hensley (1977) on zooplankton composition

in the upper 100 m off northern Cuba, and by McLelland (1978)

1Rosenstiel School of Marine and Atmospheric Science, Division of Biology and

Living Resources. 4600 Rickenbacker Causeway, Miami, FL 33 I49

on chaetognaths in the northeastern Gulf of Mexico have added

information on occurrence and distribution in these areas.

The occurrence of the benthic genus Spadella in the western

North Atlantic was discussed by Owre (1963), who described two

new species and wrote a key to the species then known, In 1970,

Aivariiio described a new species from Puerto Rico. Further information on characteristics and distribution appeared in a report on

extensive Bahamian collections (Owre 1972b).

The physiological ecology of chaetognaths has been investigated through laboratory studies on Sagitta hispida, a common

species in neritic Florida, Gulf and Caribbean waters, the oceanic

Sagitta enflata, and the benthic Spadella cephaloptera (Reeve

1964a, 1966, 1970a, b; Reeve and Cosper 1975; Reeve and Lester

1974; Reeve et al. 1970; Reeve and Walter 1972a, b; Feigenbaum

1977, 1978; and Feigenbaum and Reeve 1977),

The occurrence and distribution of chaetognaths in the tropical

western Atlantic are thus generally well known, but no single

work treating both benthic and planktonic species and serving as a

guide to identification and distribution exists, In view of the growing interest of the many Caribbean countries, as well as the United

States, in marine ecosystems, comprehensive reference works for

use in teaching and research are needed. The Chaetognatha, as

primary planktonic predators in the marine food web as well as

valuable indicators of water masses, grow in significance as more

is learned of their ecology. New data have emerged on the

horizontal and vertical distribution and the systematics of the

group from surveys in the Caribbean and adjacent areas (Owre

and Foyo 1971, 1972; Owre 1973; Michel et al. 1976; Stepien

1980). It is now appropriate to summarize this information, providing an illustrated key to benthic and planktonic species, with

an abbreviated diagnosis of each species and information on

distribution,

With the exception of a few works of historical interest, the

Literature Cited primarily concerns literature pertaining to the

chaetognaths of the southwestern North Atlantic, Gulf, and Caribbean areas, Extensive bibliographies are found in the works of

Hyman (1959), Ghirardelli (1968), and Aivariiio (1969).
• ,

.. ...

..

',\ .

, .

. '.

.

b

Figure I.-Locations of stations at which complete series of plankton samples were collected In nets towed horizontally

at as many as 13 levels, usually 6 or 7, hetween the surface and depths near hottom (after Michel et al. 1976).

CLASSIFICATION

Anatomy

The morphology of chaetognaths has been described in several

monographs summarized by Hyman (1959) and Ghirardelli

(1968). Most of the features of gross morphology currently used in

the identification of genera and species are shown in Figure 2.

The elongated body is differentiated into three regions, head,

trunk, and tail, sometimes called the caudal segment. Transverse

septa partition the head from the trunk and the trunk from the tail.

Total length (L) is measured from the tip of the fleshy head at the

midline to the tip of the tail, excluding teeth which may protrude

anteriorly and the caudal fin posteriorly. As Thompson (1947)

pointed out, Ritter-Zilhony (1911 b) recommended this measurement because of the delicacy of the caudal fin. Unfortunately,

some workers have included the fin, and thus not all published

measurements are comparable. The length of the tail (T), i.e., from

the transverse septum to the tip, excluding the caudal fin, is

routinely used as a specific character when expressed as a percentage of the total length: TIL = T%.

One or two pairs of lateral fins, in the latter case called anterior

fins and posterior fins, and a caudal fin are always present. These

are not muscular structures but thin lateral extensions of the

epidermis, stiffened by rays which may support all of the fin or

parts of it or, in the case of Bathybelos typhlops, be lacking

altogether. Ghirardelli (1968) rejected the suggestion that the fin

rays are made of collagen; their composition apparently remains

unknown. The number of lateral fins, their position on the body,

and the shape and sometimes the arrangement or absence of the

fin rays are all useful characteristics in well-preserved specimens.

2

The student normally encounters difficulty in seeing the form and

extent of the lateral fins and must learn to manipulate the microscope light and the specimens to reveal these features. Robert

BierF recommends staining with aniline blue, which can be

prepared as a strong aqueous solution and used drop by drop,

according to the amount of fluid containing the specimens. The

stain emphasizes the fins. Phase contrast and dark-field microscopy are also effective in showing external structures.

Species of the benthic genus Spadella are adapted to adhere to

the substrate by glandular areas on the posterior part of the body.

In most species, these adhesive structures occur at the tips of

digitate extensions from the lateral or caudal fins or from the tail

itself (see Figs. 7, 8). In Spadella cephaloptera, the glandular areas

are located on the ventral side of the tail, and there are no digitate

processes (see Fig. 6).

On the head, in an anterior-ventral position, are one or two

paired rows of small, elongate teeth, except in the deep-living,

little-known genus Krohnittella, which has no teeth. If there are

two pairs of rows, as in Sagitta and Pterosagitta, the anterior rows

are called the anterior teeth and those posterior, the posterior teeth

(Fig. 3). In species of Spadella, there usually are no posterior teeth

although a few may be present in S. cephaloptera. The genera

Eukrohnia and Krohnitta have only a single pair of rows of long

teeth (Fig. 4). Several much larger curved, grasping hooks are

'R. Bieri, Professor, Environmental Studies Center. Anlioch College. Yellow

Springs, OH 45387, pers. commun. July 1978.
Figure 2.---Sagitla enjlaJa, dorsal view: A diagram showing gross anatomy.

E

E

II)

o

II

II

fI)

o

Figure 4.-Krohnitla sub/ilis, ventral view of

head.

Figure 3.---Sagi//a plane/onis, forma ze/esios, Immature, ventral view of head.

seminal vesicle

anterior teeth

posterior teeth

corona ciliata

collarette

ventral ganglion

anterior fin

posterior fin

anus

testis

5.0 mm

tail

trunk

ovary

hook

eye

mouth

intestine

caudal fin

seminal receptacle

transverse septum

L: 11.8 mm; T% 28

H (hooks on each side): 7-8

Ta (anterior teeth on each side): 9-8

Tp (posterior teeth on each side): I I-II.

In characterizing a species, authors usually have tabulated the

range of T% and numbers of teeth and hooks for a particular size

range, either as found in one collection or else as a summary of

knowledge, e.g., Ritter-Zahony's (1911 a) data (Table I).

situated in a row on each side of the head (see Figs. 2, 3,4). The

formation and position of these structures, as well as the number

present in an animal of a particular length, all serve as taxonomic

characteristics. The total number of teeth of each kind on each

side of the head is counted. In identifying a chaetognath, the

figures for total length, the percentage the tail occupies (TIL), and

the numbers of teeth and hooks can be specified in the following

way:

3
Table I.-Data of 2S Sagitta bipunclala from the Atlantic Ocean (from Rltter-Zilhony 1911a).

Length Anterior Posterior

(mm) T% Hooks teeth teeth

19 21 10 6 16

15 23 8-9 7-8 14-15

14 24-25 9-10 7-8 13-15

13 23-25 8-10 6-7 12-16

12.5 24-25 8-9 6-8 12-14

12 23-26 9-10 5-7 13-14

11.5 24-26 9-10 5-6 13

II 28 9-10 7 14

The two small eyes on the dorsal surface of the head consist of

five cups (cupolae) which are pigmented except in some meso-and

bathypelagic species. The size, shape, orientation, and pigmentation of the cups may serve as taxonomic characters (Ghirardelli

1968). I have found them useful in differentiating immature Sagitta hispida and S. helenae, as did Tokioka (1955), and mature S.

decipiens (see Fig. 19). Eakin (1968), Eakin and Westfall (1964),

and Ducret (1975, 1977) have made extensive studies of the structure and ultrastructure of the chaetognath eye.

When a chaetognath is not seeking food or feeding, the head is

streamlined by a fold of the body wall, the hood, which extends

over the hooks and teeth. Fortunately, animals usually retract the

hood when dying in preservative; if it remains in place, it must be

dissected to reveal teeth and hooks.

In some species, the epidermis commencing in the region of the

neck consists of large vacuolated cells which form a structure of

varying thickness termed the collarette. The collarette may be

restricted to the neck (see Fig. 39), reach the anterior fins (see Fig.

35), or extend to or past the transverse septum (Fig. 5). It is

sometimes damaged or destroyed during collection.

On the dorsal surface of the head and neck, sometimes extending onto the trunk, is the corona ciliata or ciliary loop. Staining is

required in order to see it on preserved specimens of most species.

The species of Spadella treated here are exceptions. The corona is

a delicate epidermal structure which may be abraded during capture. Although Ritter-Zahony (1911 a, b) and others have considered its form a good taxonomic character, it can be variable, as

Ghirardelli (1968) pointed out in his thorough discussion. Neither

its histological structure nor its function has been finally determined by the several workers who have studied it, but they seem

to agree that it consists of two concentric rings of cells of ectodermal origin. These are difficult to differentiate in pelagic chaetognaths and supposedly are composed of the same kind of cell. In

Spadella, however, the inner corona is formed by pyriform glandular cells and the outer by smaller ciliated cells. Some believe

that a narrow canal separates these two and that the organ is excretory. Others think that its function is largely sensory. Also, in a

long series of observations and experiments summarized in his

1968 work, Ghirardelli showed that, in Spadella cephaloptera, the

secretions and ciliary action of the corona contribute to the movement of sperm to the seminal receptacles after reciprocal copulation has resulted in the deposit of a spermatophore in the dorsal

neck region.

On the ventral surface of the anterior trunk lies a prominent

rectangular structure, the ventral ganglion. This is the center for

innervation of the trunk and tail. The location of the anterior edge

of the fins and the extent of mature ovaries with reference to the

ventral ganglion are features which may be used in taxonomy. As

the ganglion is epidermal and superficial, rough handling may

dislodge it, but it usually remains attached by one of the nerves

which issue from it.

The presence of minute projections from the body surface,

arranged in orderly rows, has been recognized for more than a

century. The structure and function of these ciliated epidermal

sensory receptors have recently been examined by Feigenbaum

and Reeve (1977) and Feigenbaum (1978), who refer to the more

numerous kinds as "hair fans," and by Bone and Pulsford (1978),

who call them "ciliary fences." Using a scanning electron microscope to view Spadella cephaloptera, Bone and Pulsford found two

kinds of sensory structures in addition to the ciliary fences, stout

single cilia on head and tail, and, on the head, presumed sensory

cells with ciliated invaginations of the cell surface. They further

observed groups of pointed bristles scattered over the body surface

and noted that they are distinct from the sensory cilia. The hair

fans or ciliary fences, which have also been studied in Spadella

schizoptera, several species of Sagitta, and Pterosagitta draco,

enable the organism to receive near-field low frequency vibrations

(Feigenbaum and Reeve 1977; Bone and Pulsford 1978).

The general aspect of the body is used to separate two groups

within the genus Sagitta. Most species are relatively slender with

strong longitudinal musculature so that the body tends to be rigid

when preserved, e.g., S. bipunctata, S. hispida, and S. serratodentata (see Figs. 18,26,37). In others, the body is broader, more

inflated and less heavily muscled in comparison, and it may

collapse during capture so that the preserved animal has a flaccid

appearance. Examples of the latter form are S. enflata, S. hexaptera, and S. lyra (see Figs. 20,25,27).

Within the body, the three coelomic cavities are located in the

head, the trunk, and the tail. Coelomic space in the head is virtually obliterated by muscles, nervous tissue, and anterior portions of

the digestive system. It is separated from the trunk coelom by a

transverse septum, and another septum partitions the trunk from

1.0 mm

Figure S.--Plerosagitta draco, dorsal view.

4
the tail coelom (see Fig. 2). There are commodious coelomic

spaces in trunk and tail. In the trunk, the space is divided longitudinally into two compartments by the median dorsal and ventral mesenteries which support the intestine. The tail coelom is

also divided by a median, longitudinal, dorsoventral mesentery,

represented in Figure 2 by a dashed line. In her summary, Hyman

(1959) stated that "A true coelom is formed by the enterocoelous

method during the embryonic stages of chaetognaths, but this is

suppressed in the larva.... At any rate the definitive space between body wall and intestine and in the tail is not lined by a

peritoneal membrane." This is a prevalent opinion. However, routine thin-sections I prepared in 1952 caused me to question this,

and electron photomicrographs made by G. Hendrix (unpublished) further suggest that the trunk cavity, at least, is a true coelom.

The digestive system consists of a large ventral mouth and

vestibule opening into a pharynx (sometimes termed esophagus)

which extends through the septum between head and trunk and is

continuous with the intestine. At the anterior end of the intestine,

a pair of lateral diverticula may extend forward toward the septum. The presence or absence of the diverticula is a characteristic

used by Alvariiio (1969) and others in grouping species which appear to be closely related, e.g., the "bipunctata" group (without

diverticula) and the "hispida" group (with diverticula). In the case

of species which inhabit similar environments and are difficult to

differentiate until fully mature, such as Sagitta hispida and S.

helenae in the Caribbean area, the presence or absence of the

diverticula may be an important characteristic. The intestinal

tube, supported by dorsal and ventral mesenteries, extends posteriorly to the ventral anus, located at the end of the trunk and therefore not a terminal aperture.

In contribution of considerable systematic importance, Dallot

(1970) called attention to the lack of information on the structure

of the intestine. He distinguished between the common simple

type and a more complex type, characterized by voluminous

vacuolar cells in the intestinal wall, which he compared in nine

species. These are Sagitta bedoti Beraneck, 1895; S. decipiens

Fowler, 1905;5. elegans Verrill, 1873;S. megalophthalma Dallot

and Ducret, 1969; S. marri David, 1956; S. minima Grassi, 1881;

S. neodecipiens Tokioka, 1959; S. planctonis Steinhaus, 1896; and

S. zetesios Fowler, 1905. I have found this characteristic useful in

identifying immature S. planctonis forma zetesios, as explained in

the comments on that form.

The paired ovaries, oviducts, vaginas, and seminal receptacles

are located in the trunk coelom, one set on either side of the intestine. The length of the mature ovary and sometimes the size and

shape of the mature eggs, though transitory features, are occasionally used in identification. The paired testes and sperm ducts are

similarly located in the tail coelom. Sperm pass from the ducts into external structures, the seminal vesicles, where they are formed

into spermatophores and stored until released for fertilization. The

shape of the mature vesicles as well as their location with respect

to lateral and caudal fins are reliable taxonomic characteristics.

Methods

The routine preservatives used for chaetognaths are 70%

alcohol or 5-10% Formalin, the latter being far superior. All

samples in the Caribbean collections were preserved immediately

after arrival on shipboard in 10% Formalin, buffered with hexamethylene tetramine. This buffer is no longer recommended

because it adversely affects both external fine structure and internal anatomy in copepods and other planktonic animals. Borax is

the preferred buffer.

The equipment needed for working with chaetognaths is a

dissecting microscope for general viewing; a compound microscope for examining teeth and other small structures; a widemouth pipette, e.g., a medicine dropper; fine forceps; and a pair of

fine dissecting needles. A stainless steel needle or size 000 insect

pin (head removed), with the shank inserted into a wooden stick,

makes a good needle. Specimens should always be totally immersed in fluid, whether in a dish or on a slide with cover slip. Strong

transmitted light should regularly be used in making observations

with a dissecting microscope. Although staining is rarely

necessary for identification, some workers use solutions of aniline

blue or methylene blue, mainly to see the corona ciliata and the

fins.

Most observations and measurements can be made using a dissecting microscope equipped with an ocular micrometer. Large

specimens may be more conveniently measured using a transparent metric rule. Their hooks and even their teeth can often be

counted with the magnification provided by a dissecting microscope. If higher magnification is required, the specimen must be

mounted on a slide ventral side up, in fluid, and covered in order

to count the teeth with the use of a compound microscope. Occasionally an animal will contract so that a dorsal view of the head is

also required to enumerate the teeth accurately.

Maturity in chaetognaths is signaled by the presence of ovaries

containing large eggs, testes producing spermatozoa, and seminal

5

vesicles, the form and position of which are diagnostic in many

species. If the animal has recently discharged spermatozoa, the

vesicles will be more or less transparent, but the outline of the

adult structure can usually be seen.

Although mature animals are the easiest to identify, it is quite

possible to classify most immature specimens, except for tiny

juveniles, by using combinations of several characteristics. It is

helpful to know the habitat from which the specimen came,

planktonic or benthonic, neritic or oceanic, and, if oceanic, from

what depth. A generic diagnosis can readily be made by determining the number and position of lateral fins and whether or not they

are supported by rays, the presence or absence of a collarette, and

the number of rows of teeth. Usually specific identification of an

immature form can then be made by measuring the total length

and finding the percentage that the tail occupies, examining and

counting teeth and hooks, and observing such features as presence

or absence of intestinal diverticula and collarette and, if necessary,

the shape and extent of the corona ciliata.

Caution must be used in drawing conclusions based on fine

differences in measurements of soft parts of specimens from different collections. Ahlstrom and Thrailkill (1962) reported that

samples lose 15-87% of their volume at collection, most of it in

the first 24 h after preservation. Shrinkage continues over a varying period, with comparative stability reached in 1 to 2 yr. Owre

(1973), in discussing the T% relationship, pointed out that in the

known developmental patterns of chaetognaths, the T% is higher

in small specimens and gradually lessens as the animals mature.

The variation expressed as ranges in T% is a function not only of

individual difference but also of methods of preservation, time in

preservative, and precision in measuring. Owre used measurements of two groups of the small species Krohnitta pacifica,

preserved for over 2 yr, to demonstrate the inconsistency of the

relationship. This is also illustrated by data on Eukrohnia bathy-
pelagica, in which the T% appears to be least (25%) in the

smallest individuals and increases with length until it reaches the

broad range of 27 -34% in medium-sized organisms.

It would be impractical to attempt constructing a key to

immature forms because the meristic characters which must be

combined for a diagnosis change with age. Thus, the present key is

intended for the identification of relatively undamaged, mature

specimens, although it will work for immature forms of many

species. Students who keep the specimen completely immersed

and learn to manipulate it and the illumination to show fins and

other structures, should be able to make correct identifications.

However, novices must always take the precaution of verifying

their identification by consulting a description of the species.

Taxonomy

Except for descriptions of new species, the taxonomy within the

Phylum Chaetognatha remained essentially the same as that

published in Ritter-Zahony's revision (I91la) until Tokioka's

(1965a) expanded classification appeared. Rather than establish

formal taxa, sev·eral workers formed groups of species intended to

express relationships, particularly within the largest genus, Sagitta.

Alvariiio (1965) summarized 10 of these and later (1969)

presented her own list of groups within Sagitta. In general, these

groups are disparate and have resulted in little advancement of our

knowledge of relationships within the phylum because of the lack

of agreement among specialists as to which characteristics are

valid both taxonomically and phylogenetically. As the group is

largely homogeneous in major anatomical features, a simple

classification of genera and species, without supercategories, has

sufficed for the purpose of identification.

Claus and Grobben (1905) erected the Class Sagittoidea to include the species then known, all of which were extant. In the only

formal presentation of an enlarged classification, Tokioka

(1965a) proposed a second class, two orders, two suborders, five

families, and six new genera. To include the fossil species

Amiskwia sagittiformis Walcott, 1911, Tokioka created the Class

Archisagittoidea, although Owre and Bayer (1962) had recommended removing it from the Chaetognatha to the Nemertinea

and this view received the approval of both Ghirardelli (1968)

and Beklemishev (1969). Tokioka joined the new families Spadellidae (Spadella) and Eukrohniidae (Eukrohnia, Heterokrohnia,

and Bathyspadella) in the Order Phragmophora, characterized by

the presence of ventral transverse musculature and greater or

lesser development of glandular structures on the body surface,

particularly in the cephalic and neck regions. The Order Aphragmophora was erected for those forms lacking ventral transverse

musculature, with little or no development of glandular structures

on the body surface. The Suborder Ctenodontina (gently curved

hooks, comb-shaped tooth rows, and slender teeth) includes the

Family Sagittidae Claus and Grobben 1905, and the new Family

Pterosagittidae, represented by Pterosagitta draco. The Suborder

Flabellodontina (relatively abruptly curved hooks, with stouter

teeth than in the Ctenodontina, arranged in a fan shape) contains

the new Family Krohnittidae and the genus Krohnitta. As workers

are not obliged to use the supertaxa, the aspect of Tokioka's

classification which commands the most attention is the partition

of Sagitta into nine genera: Sagitta sensu strictu; Serratosagitta and

Aidanosagitta, erected by Tokioka and Panthansali in 1963; and

6

Tokioka's new genera in 1965, Zonosagitta, Parasagitta,

Mesosagitta, Solidosagitta, Caecosagitta, and Flaccisagitta. The

separations are based largely on the structure of the corona ciliata,

presence or absence of intestinal diverticula, distribution of rays

in the lateral fins, the degree of pigmentation of the eyes, and

characteristics of the seminal vesicles.

Tokioka (l965b) used his scheme of classification as a framework to express his views of phylogenetic relationships within

this ancient, enigmatic group. In summary, benthic Phragmophora

gave rise to bathypelagic phragmophores as well as neritic

Aphragmophora, from which oceanic aphragmophore species living in epipelagic, mesopelagic, and bathypelagic realms evolved.

Ducret's (1977) intricate study of chaetognath eyes has lent support to Tokioka's views.

The objective of the present work is to enable the student to

identify species of chaetognaths in the southwestern North Atlantic, the Florida Straits, the Gulf of Mexico, and the Caribbean Sea.

Since most authors of ecological works involving chaetognaths

continue to use the simple classification of Ritter-Zahony (1911 it,

b), also employed by Hyman (1959), Ghirardelli (1968), Aivariiio

(1967, 1969), and others, the genus Sagitta as defined by RitterZahony will be used here.

The common pelagic genera Eukrohnia, Krohnitta, and Sagitta

and the benthic Spadella contain the majority of the approximately 70 species known. The monospecific Pterosagitta draco occurs

in abundance in the upper layers of temperate and tropical

oceanic waters. Five other genera have been described, three of

which are monospecific: Zahonya (Z. cestoda Oye, 1918), of

doubtful validity (Tokioka, 1965a), Bathyspadella (B. edentata

Tokioka, 1939), and Bathybelos (B. typhlops Owre, 1973). Two

species of Krohnittella Germain and Joubin, 1912, are known, K.

boureei Germain and Joubin, 1912, from two specimens, and K.

tokiokai Bieri, 1974, from one specimen. Bieri (1974) believed

this genus may be bathybenthic. The bathypelagic Heterokrohnia

Ritter-Zahony, 1911 a, was described from Antarctic material (H.

mirabilis Ritter-Zahony, 1911 a). Heterokrohnia mirabilis has since

been reported from the Antarctic (David 1958b) and elsewhere

(Tchindonova 1955; Bieri 1959; Dawson 1968). Two other

species of Heterokrohnia are known, H. bathybia Marumo and

Kitou, 1966, and H. involucrum Dawson, 1968.

The 6 genera and 28 species, known to occur in the Caribbean

Sea, the Gulf of Mexico, and the southwestern North Atlantic and

treated here, are named in the following list.
List of Species

Class Sagittoidea Claus and Grobben, 1905

Order Phragmophora Tokioka, 1965a

Family Spadellidae Tokioka, 1965a

Spadella Langerhans, 1880

Spadella cephaloptera (Busch, 1851)

S. nana Owre, 1963

S. pulchella Owre, 1963

S. schizoptera Conant, 1895

Family Eukrohniidae Tokioka, 1965a

Eukrohnia Ritter-Zahony, 1909

Eukrohnia bathyantarctica David, 1958

E. bathypelagica Aivariiio, 1962

E. fowleri Ritter-Zahony, 1909

E. hamata (Mobius, 1875)

E. proboscidea Furnestin and Ducret, 1965

Order Aphragmophora Tokioka, 1965a

Suborder Ctenodontina Tokioka, 1965a

Family Sagittidae Claus and Grobben, 1905

Bathybelos Owre, 1973

B. typhlops Owre, 1973

Sagitta Quoy and Gaimard, 1827

Sagitta bipunctata Quoy and Gaimard, 1827

S. decipiens Fowler, 1905

S. enflata Grassi, 1881

S. friderici Ritter-Zahony, 1911

S. helenae Ritter-Zahony, 1910

S. hexaptera d'Orbigny, 1843

S. hispida Conant, 1895

S. lyra Krohn, 1853

S. macrocephala Fowler, 1905

S. megalophthalma Dallot and Ducret, 1969

S. minima Grassi, 1881

S. planctonis forma planctonis Steinhaus, 1896

S. planctonis forma zetesios Fowler, 1905

S. serratodentata Krohn, 1853

S. tenuis Conant, 1896

Family Pterosagittidae Tokioka, 1965a

Pterosagitta Costa, 1869

P. draco (Krohn, 1853)

Suborder Flabellodontina Tokioka, 1965a

Family Krohnittidae Tokioka, 1965a

Krohnitta Ritter-Zahony, 1910

Krohnitta pacifica (Aida, 1897)

K. subtilis (Grassi, 1881)

KEY TO MATURE CHAETOGNATHA

1a. A single pair of lateral fins, which may be short (Fig. 40) or elongate (Fig. 11) or bilobed, owing to the development of

seminal receptacles (Fig. 8).. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2

1b. Two pairs of lateral fins (Figs. 2, 18) 13

2a. Lateral fins confined to the caudal segment; with a thick collarette extending from neck to fins in undamaged specimens

(Fig. 5) Pterosagitta draco p. 29

2b. Lateral fins extending along portions of both caudal and trunk segments (Figs. 8,40). 3

3a. With a more or less prominent collarette; benthic animals of the genus Spadella 4

3b. Without a collarette; planktonic animals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7

4a. With digitate or irregularly shaped adhesive structures on the tail (Fig. 8). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5

4b. Without such adhesive structures but with adhesive glands on the ventral surface of the tail (Fig. 6) Spadella cephaloptera p. 10

5a. Adhesive structures originate from the posterior edge of the seminal vesicles, are attached laterally, and are confluent with

the caudal fin (Fig. 7b) Spadella pulchella p. 11

5b. Adhesive structures extend from the ventral body wall or the posterior portion of the lateral fins or both, not from the

posterior edge of the seminal vesicles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6

6a. Each adhesive structure is divided into four to six slender processes (Figs. 7a, 8) Spadella schizoptera p. 13

6b. Each adhesive structure is divided into two slender processes, or, in very small specimens, the structure may be undivided

(Fig.7c) Spadella nana p. 11

7a. Lateral fins extending anteriorly to the level of the ventral ganglion (Fig. II); hooks usually serrated in juveniles.

Eukrohnia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8

7b. Lateral fins not extending far anteriorly, never to the ventral ganglion (Fig. 40); hooks not serrated. Krohnitta 12

8a. Eyes pigmented, only slightly in some species. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9

8b. Eyes without pigment , 10

9a. Eye pigment covering a small area which, in some specimens, is approximately triangular in shape; tip of hooks gently

curved (Fig. 11) Eukrohniafowleri p. 14

9b. Eye pigment forming a very elongated spot; tips of hooks themselves sharply hooked (Fig. 14) Eukrohnia proboscidea p. 16

lOa. No more than 10 hooks, the tips of which are themselves hooked; teeth usually 18-25 II

IDb. Hooks 11-14, with gently curved tips; teeth 16 or fewer (Fig. 9). . Eukrohnia bathyantarctica p. 13

Ila. Tail, excluding fin, relatively short, occupying 19-24% of the length of animals ranging from 43 to II mm (Fig. 12) .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Eukrohnia hamata p. 15

II b. Tail proportionately much longer than in E. hamata, occupying 24-34% of the length of specimens 23-12 mm long

(Fig. 10) Eukrohnia bathypelagica p. 14

7
12a. Relatively short, to 9 mm, with the caudal segment comprising < 30% of the total length; ovaries of mature specimens

extending well beyond the anterior edge of the lateral fins, often to the level of the ventral ganglion (Fig. 40). . .

........................ .Krohnitta pacifica p. 29

12b. Longer, to approximately 16 mm, with a long tail comprising 30-40% of the total length; mature ovaries usually not

extending beyond the anterior edge of the lateral fins but ifso, for only a short distance (Fig. 41) Krohnitta subtilis p. 30

13a. The two pairs of lateral fins supported to some extent by stiffening rods or rays (Fig. 25); eyes pigmented (exception:

Sagitta macrocephala, 27b, Fig. 28). Sagitta 14

13b. The lateral fins rayless; eyes either altogether absent or lacking pigment; bathypelagic (Figs. 16, 17) Bathybelos typhlops p. 17

14a. Body broad, inflated, and translucent, owing to comparatively weak development of longitudinal muscle bands; mature

specimens large, approximately 15-40 mm long (Figs. 20,25,27) 15

14b. Body comparatively slender, rigid, and opaque (Figs. 18,26); mature specimens of most species < 20 mm long (exceptions:

Sagitta planctonis, 19 a and b, and S. megalophthalma, 20 a, Figs. 30,35) 17

15a. One to four, usually three, very long slender anterior teeth (Fig. 25). . Sagitta hexaptera p. 21

15b. Anterior teeth not especially long and slender 16

16a. Anterior and posterior lateral fins connected by an area of thickened epidermis (Fig. 27) Sagitta lyra p. 22

16b. Lateral fins not connected by thickened epidermis but separate, rounded, and short (Fig. 20). . Sagitta enflata p. 18

17a. With a well-developed collarelle (Figs. 35,36) 18

17b. Collarelle either very small or lacking 25

18a. A prominent collarelle of more or less uniform thickness throughout, extending at least from neck to anterior fins in

mature forms but often less extensive in immature specimens (e.g., S. planctonis forma zetesios); intestinal walls characterized by voluminous vacuolar cells which are easily discernible through the body wall 19

18b. Collarette not extending to the anterior fins 20

19a. Posterior teeth usually < 14; an epi-mesoplanktonic form3 (Fig. 35). . Sagitta planctonis forma planctonis p. 26

19b. Posterior teeth usually more than 14; a meso-bathypelagic form (footnote 3) (Fig. 36) Sagitta planctonis forma zetesios p. 27

20a. Pigmented zone of the eye approximately rectangular and unusually large; 3-4 rows of vacuolar cells on each side of the

intestine; total length may exceed 20 mm (Figs. 30-33) Sagitta megalophthalma p. 24

20b. Pigmented zone of the eye not unusually large; intestinal walls of the simple type, without conspicuous vacuolar cells;

total length at maturity usually <20 mm 21

21 a. Anterior teeth unusually numerous, e.g., 8-10 in 6-7 mm specimens, 15-17 in 14-15 mm specimens; intestinal diverticula

absent (Figs. 23, 24) Sagitta helenae p. 20

21 b. Anterior teeth not as numerous as in S. helenae 22

22a. Seminal vesicles adjacent to the caudal fin and separated from the posterior lateral fins; 4-7 anterior teeth, with their bases

closely spaced tangents along an arc roughly at right angles to the longitudinal body axis and their axes radiating in a fanlike arrangement; intestinal diverticula absent (Fig. 18) Sagitta bipunctata p. 17

22b. Seminal vesicles adjacent to the posterior lateral fins; anterior teeth not arranged as in S. bipunctata 23

23a. A stout primarily neritic species with a well-developed collarelle; seminal vesicle separated by about half its mature length

from the caudal fin; intestinal diverticula present (Fig. 26) Sagitta hispida p. 21

23b. Slender neritic species, with a small collarette in the neck region; mature seminal vesicles extending to both posterior

lateral and caudal fins; intestinal diverticula absent 24

24a. A short species, mature at 5-8 mm and rarely exceeding 8 mm in length; mature ovary short, containing a few, usually <

10,Iarge ova, arranged in a single row (Fig. 39) Sagitta tenuis p. 28

24b. A longer species, reaching approximately 13.5 mm and maturing at a larger size than S. tenuis; mature ovary longer than in

S. tenuis, containing many small ova, arranged in two or more rows (Figs. 21, 22) Sagittafriderici p. 19

25a. Hooks usually 6-7 on each side, finely serrated; in mature specimens, distinctive, projecting, seminal vesicles, well

separated from the caudal fin (Figs. 37,38) Sagitta serratodentata p. 27

25b. Hooks not serrated 26

26a. A small species, no longer than 9 mm; ova few and very large in mature ovaries, which do not extend beyond the anterior

edge of the posterior lateral fins; ovoid seminal vesicles adjacent to caudal fins; anterior fins narrow and mostly rayless;

rays of posterior fins usually perpendicular to the body wall (Fig. 34) Sagitta minima p. 25

26b. Without the characteristics ofS. minima 27

27a. A species with a relatively small head; anterior fin extending to the ventral ganglion and usually rayless in the anterior

portion; posterior fin relatively broad; pigmented eyes of mature specimens distinctly elongated (Fig. 19).....Sagitta decipiens p. 18

27b. A species distinguished by an exceptionally large head, longer than broad, with numerous dark brown hooks and teeth;

eyes without pigment; anterior fin short, not extending to the ventral ganglion; posterior fin much larger than the anterior,

with an inner rayless zone (Figs. 28,29) Sagitta macrocephala p. 23

'From David (1956) and Pierrot·Bults (1975).

8
DESCRIPTIONS AND DISTRIBUTIONS

Table 3.-Vertical distribution of Cbaetognatba in the Caribbean Sea and adjacent regions, with species arranged in order of frequency of occurrence from the

surface to depths below 1,000 m and showing tbe estimated total numbers, derived from counts of some entire samples and aliquots of otbers, collected in tbe

epi-, meso·, and bathypelagic realms (after Michel et al. 1976.).

North Atlantic Central Water (NACW), characterized by gradually diminishing temperature and salinity, extends between SUW

and the colder, less saline (5 0 _8°C, 34.69-35.120 / 00) Subantarctic

Intermediate Water (SAIW). This water mass is found at approximately 700-1,200 m, below which North Atlantic Deep Water

(NADW) and Caribbean Bottom Water (BW) fill the basins.

An abbreviated synonymy and brief description of each species

is followed by a summary of information on its distribution within

the specified areas. Michel et al. (1976) discussed vertical distribution of pelagic forms in detail. Some of the data on which the

discussion was based are included in Tables 2 and 3. The only

neritic species found in that study of oceanic regions, Sagitta

helenae and S. hispida, were strays which had been transported

from nearshore environments. They, with S. jriderici and S. tenuis,

also common neritic forms in the area, are ordinarily epipelagic

when found in oceanic waters. However, S. helenae, S. hispida,

and S. tenuis have been collected at more than 650 m in the

Florida Straits, indicating entrainment of surface waters in the

deep flow beneath the Florida Current (Stepien 1980).

Although most oceanic species have broad vertical ranges, their

greatest numbers are found over a comparatively limited distance

(Table 2). As Michel et al. (1976) pointed out, some records of

epipelagic species at relatively great depths no doubt result from

contamination. However, during their study, special precautions

were taken to eliminate from the counts desiccated specimens and

those obviously moribund at preservation. It appears that at least

some of the deep records are real, as Stepien (1980) found,

although they may be difficult to interpret. In Table 3, all of the

species collected are arranged in order of their occurrence in relation to the broad ranges in depth termed epi-, meso-, and bathypelagic realms.

Throughout the reports of vertical distribution in the Caribbean

area, reference will be made to the water masses from which the

species have been collected. A summary of the general characteristics of depth, temperature, and salinity of these water masses

follows. The Tropical Surface Water (TSW) forms the upper

50-100 m and, because of precipitation and evaporation, is broadly variable in temperature (approximately 22°-29°C) and salinity

(33-38% 0), The Subtropical Underwater (SUW), or Maximum

Salinity Water, beneath the TSW at approximately 100-200 m,

has salinities above 36.250 / 00 and temperatures usually < 26°C.

0-200 m 201-1,000 m

Species No. % No. %

Sagitta helenae 14 100.0

S. e/lf/ara 57,683 99.8 112 <I

Pterosagilla draco 11,701 99.8 16 <I

S. serratodentata 31,047 99.1 284 <I

Krohnitta pacifica 4,729 99.0 33 <I

S. hispida 1,119 98.9 12 l.l

S. hexaptera 8,827 92.4 718 7.5

S. bipunctata 1,987 92.0 175 8.0

S. megalophthalma 7 88.0

S. minima 110 67.0 55 33.0

K. subtilis 1,342 38.0 2,148 61.0

S. lyra 964 27.0 2,534 72.0

S. planclOnis forma

zetes;os 13 19.0 53 77.0

S. decipiens 875 6.6 12,300 93.0

E. hamata 17 100.0

S. planctonis forma

planctonis I iOO.C

E. barhypelagica 247 92.0

E. bathyantarctica 214 78.0

E. fowleri 147 75.0

E. proboscidea 3 60.0

S. macrocephala 270 57.0

Bathybelos ryphlops

>1,000 m

No. %

2 <I

6 <I

2 <I

4 <I

12.0

5 1.0

31 1.0

4.0

<I

23 8.0

61 22.0

48 25.0

2 40.0

201 43.0

I 100.0

Table 2.-Summary of the vertical ranges of the more common chaetognath species in the Caribbean Sea and

adjacent regions, the total number of samples in whicb each occurred, the estimated total number collected, and

the average number per sample obtained in the standard hour.long tow (after Michel et al. 1976). The estimated

total numbers of each species and the average number per sample are based on counts of some entire samples

and aliquots of others.

Total Range of

range maximum numbers Number of Total est. Avg. no.l

(m) (m) samples numbers sample

"Epipelagic" species

K. pacifica 0-1,835 0-100 69 4,762 69.0

P. draco 0-2,316 0-100 50 11,717 234.3

S. bipunctata 0-300 0-100 34 2,162 63.6

S. enf/ata 0-320 0-100 95 57,795 608.4

S. serratodentata 0-2,000 0-100 102 31,331 307.2

S. hexaptera 0-1,567 0-200 91 9,545 104.9

S hispida 0-250 0-60 33 1,131 34.3

S. minima 0-590 8 165 20.6

"Mesopelagic" species

K. subtilis 25-5,200 100-500 71 3,495 49.2

S. decipiens 75-2,650 200-500 90 13,183 146.5

S. lyra 25-3,000 200-600 104 3,529 33.9

S. planctonis forma zetesios 38-3,000 250-1,000 27 69 2.5

"Bathypelagic" species

E. bathyanrarctica 230-3,442 500-2,000 44 275 6.2

E. bathypelagica 433-2,118 450-1,000 47 270 5.7

E. fowleri 635-2,104 635-2,104 55 195 3.5

S. macrocephala 472-3,602 600-2,500 106 471 4,4

9
NADW is identified by temperatures below 5°C and salinities of

34.89 to 35.03% 0 ,

One enigmatic planktonic species has been found in the area,

Bathybelos typhlops, described by Owre (1973) from one specimen

collected in deep water of the eastern Gulf of Mexico. Four

species occurring in small numbers probably are indicators of

North Atlantic waters: Eukrohnia hamata, E. proboscidea, Sagitta

megalophthalma, and S. planctonis forma planctonis. All four were

collected in the Caribbean, and, excepting E. proboscidea, have

been reported from the Florida Straits (E. hamata and S. planctonis by Owre 1960; E. hamata and S. megalophthalma by Stepien

1980). The neritic species Sagitta tenuis and S. friderici appear to

have discontinuous geographic distributions which are discussed

under the species headings. The remaining species are widely

distributed and common at their primary depths of occurrence.

Previous records are summarized in Table 4.

Three of the four species of Spadella known from the western

North Atlantic have been reported as common on shallow sandy

bottoms around the Bahama Islands and off the southeast coast of

Florida (Owre 1963, 1972b). Spadella pulchella, described from

Puerto Rican specimens, was collected in the Bahamas but not off

Florida. The distribution of these organisms in the Caribbean, the

Gulf of Mexico, and the western North Atlantic is essentially

unknown.

Table 4.-Prevlous records of chaetognath species from the Caribbean Sea, the

Gulf of Mexico, the Florida Straits, and the southwestern North Atlantic. Additional records of Atlantic distribution have been summarized by Aivariiio (1969)

and Michel et al. (1976) (after Stepien 1978).

Southwestern

Caribbean Gulf of Florida North

Species Seal Mexico2 Straits' Atlantic'

Eukrohnia bathyantarctica + + + + E. bathype/agica + + + E. fow/eri + + + + E. hamata + + + + E. proboscidea + Krohnitta pacifica + + + + K. subtilis + + + + Pterosagitta draco + + + + Sagitta bipunctata + + + + S. decipiens + + + + S. enflata + + + + S. friderici + + S. helenae + + + + S. hexaptera + + + + S. hispida + + + + S. lyra + + + + S. macrocepha/a + + + + S. megalophtha/ma + + S. minima + + + + S. planctonis forma

planctonis + + + S. planctonis forma

zetes;os + + + S. serratodentata + + + + S. tenuis + + + +

IVannucci and Hosoe (1952); Suarez-Caabro (1955); Colman (1959); SuarezCaabro and Madruga (1960); Legare and Zoppi (1961); Aivariiio (l968a); Fagetti

(1968); Lewis and Fish (1969); Bjornberg (1971); Owre (l972a, 1973); Owre and

Foyo (1972); Mattlin (1974); Urosa and Rao (1974); Michel et al. (1976).

'Davis (1949); King (1949); Pierce (1951,1954,1962); Every (1968); Fagetti

(1968); Mulkana and McIlwain (1973); Owre (1973); Mclelland (1978).

'Owre (1960); Stepien (1978).

'Moore (1949); Pierce (1953, (958); Bumpus and Pierce (1955); Colman (1959);

Pierce and Wass (1962); Grant (1963a, b, 1977); Deevey and Brooks (1971);

Pierrot-Bults (1975, 1982).

Spadella cephaloptera (Busch, 1851)

Figure 6

Sagitta cephaloptera Busch, 1851.

Spadella cephaloptera, Ritter-Zahony, 1911 a; Yosii and Tokioka,

1939; Owre, 1972b.

10

Description. Length, to 9.5 mm, usually 2-4 mm in Floridian

and Bahamian waters; T%, 49-58; hooks, 7-11; anterior teeth,

2-5; posterior teeth, 0-4. Collarette, thickest at neck, extends to
0.5 mm

Figure 6.---SpadeUa cephaloptera, dorsal view.

caudal fin. Oval corona ciliata is located on head and trunk. A single pair of lateral fins is present; there are no adhesive structures.

Dislribution. Long known from British and European coasts and

the Mediterranean, and also reported from the Black Sea, Japan,

and the Caroline Islands, it appears to be cosmopolitan in

temperate and tropical seas. It is widespread in shallow Bahamian

waters and probably also in comparable habitats off southern

Florida (Owre 1972b).

Spadella nana Owre, 1963

Figure 7c

Spadella nana Owre, 1963.

Spadella nana, Tokioka, 1965; Owre, 1972b.

Description. Length, to 2.6 mm; T%, 41-50; hooks, 5-9; anterior

teeth, 1-3; posterior teeth, none. Collarette is continuous with

hood, thickest at the neck, and it extends along the base of the

lateral fin to the seminal vesicle. Corona ciliata, variable in shape,

is located on the anterior trunk in the neck region except for the

middle portion of its anterior border, which extends onto the

posterior part of the head. One pair of lateral fins originates

0.10-0.14 mm anterior to seminal receptacles and terminates just

anterior to seminal vesicles. Adhesive structures are produced

ventrally from the posterior end of the lateral fins. Each is divided

into two relatively stout, distally tuberculate processes which contain muscle fibers originating from both dorsal and ventral

longitudinal muscle bands. In very small specimens, the structure

may terminate in a single process.

Distribution. Spadella nana is abundant in shallow waters of

southeastern Florida and the Bahama Islands (Owre 1972b).

Spadella pulchella Owre, 1963

Figure 7b

Spadella pulchella Owre, 1963.

Spadella pulchella, Tokioka, 1965.

Spadella hummelincki Aivariiio, 1970.

Spadella pulchella, Owre, 1972b, 1973.

Description. Length, to 3.5 mm; T%, 52-59; hooks, 8-10;

anterior teeth, 2-4; posterior teeth, none. Collarette, prominent at

the neck and on the anterior trunk, extends along the bases of the

lateral fins to a point on the caudal segment approximately 0.5

mm posterior to the transverse septum. Broad, irregularly oval

corona ciliata is located anteriorly on the trunk except for a short

loop in the middle of the anterior border which extends onto the

head. Lateral fins originate approximately 0.07-0.10 mm anterior

to the seminal receptacies and reach the seminal vesicles.

II

Adhesive structures do not ongmate from the lateral fins but

extend from the seminal vesicles along the side of the caudal segment to an area of attachment at the base of the caudal fin. In immature forms, these structures may be undivided flanges with

irregular posterior borders, whereas in older specimens they may

be separated into two or three digitations, with numerous, c1oseset, distal tuberculations.

Distribution. Spadella pulchella was described from specimens

collected in a net haul near bottom in the Mayagueyez Canal, La

Parguera, Puerto Rico. Since then, Owre (1972b) has reported it

from two locations in the .Bahama Islands, where it was rare compared with S. cephaloptera, S. nana, and S. schizoptera. Owre suggested that it may prefer more estuarine conditions than the

others. There are no records from the continental United States.
b

E

E

It)

d

c

E

E

It)

d

Figure 7.-8. Spadel", schizoptera, immature; b. Spadella pllichella; c. Spadella nana; all dorsal view.

12
Spadella schizoptera Conant, 1895

Figures 7a, 8

0.5 11Im

Figure 8.-Spadella schizoptera, dorsal view.

Spadella schizoptera Conant, 1895.

Spadella schizoptera, Ritter-Zilhony, 1911a; Yosii and Tokioka,

1939; Mawson, 1944; Owre, 1963, 1972b; Tokioka 1965a.

Description. Length, to 4.9 mm; T%, 42.0-53.7; hooks, 8-11;

anterior teeth, 2-4; posterior teeth, none. A thick collarette is present. Corona ciliata, located mainly on the head, is somewhat

triangular or pyriform. Anterior and posterior lateral fins are

separated by the conspicuous seminal receptacles and vaginal

canals. Posterior lateral fins terminate in adhesive structures

which are produced ventrally at the level of the origin of the

caudal fin. Each of these is divided into four to six digitiform processes, usually four in Atlantic specimens, which contain muscle

fibers originating from either side of the mid-ventral line.

Distribution. Reported from Japan, Australia, Florida, and the

Bahama Islands, this species is abundant in the latter two localities, where it appears to prefer sandy bottom, supporting plant

growth, at depths of approximately 1-15 m (Owre 1972b). Conant

(1895) described the species from three specimens caught in a

plankton net on a rising tide at Bimini, Bahamas. In Japan, Yosii

and Tokioka (1939) collected one from the same still waters

among Zostera in which S. cephaloptera was abundant. Perhaps

the most interesting record is that of Mawson (1944), who redescribed the species from 20 specimens taken at two trawling stations of 70 and 100 m depth off New South Wales. Both bottoms

are fine sand, the shallower one with detritus; no algae occur on

either bottom.

Eukrohnia bathyantarctica David, 1958

. Figure 9

Eukrohnia fowleri (partim), Ritter-Zilhony, 1911 a.

Eukrohnia sp. David, 1958a.

Eukrohnia bathyantarctica David, 1958b.

Eukrohnia bathyantarctica, Fagetti, 1968; Alvariiio, 1969; Owre,

1972a, 1973.

Description. Length, to 31 mm; T%, 19.3-25.0; hooks, 9-14;

teeth, 2-16. Owre (1973) found the inner distal margin of some

ventral hooks in immature individuals, measuring 7.5-12.0 mm,

to be deeply serrated. The number of serrated hooks and also the

number of serrations on each hook are greater in smaller animals.

5.0 mm

Figure 9.-Eukrohnia bathyantarctica, dorsal view.

13
There is no collarette, and the corona ciliata has not been described. Eyes are unpigmented. Fins extend from the level of the ventral ganglion onto approximately the anterior third of the caudal

segment.

There are no intestinal diverticula. Mature ovaries are short,

with the ova lying in one row (Fig. 9) or, according to Alvariiio

(1969), two rows. David (1958b) reported that remnants of

seminal vesicles " ... project from [the1 oviduct after

fertilisation." Ovoid seminal vesicles lie close to the lateral fins,

separated by a distance approximately equal to their length from

the caudal fin.

Distribution. David (l958b) described this species from 1,000

to 2,400 m in the Southern Ocean and considered it endemic in

the Antarctic. However, it has a far broader horizontal distribution than originally thought, having been reported from the Caribbean Sea and Gulf of Mexico (Fagetti 1968; Owre 1972a) and

from the Straits of Florida (Stepien 1980). In the Caribbean, it has

been collected over an extensive vertical range, 230-3,442 m, but

primarily from Subantarctic Intermediate Water and North Atlantic Central Water (Michel et al. 1976). As shown in Table 3, it

was most numerous in the mesopelagic realm.

Eukrohnia bathypelagica Aivariiio, 1962

Figure 10

1.0 mm

Figure lO.-Eukrohnia balhypelagica, dorsal view.

Eukrohnia bathypelagica Aivariiio, 1962.

Eukrohnia bathypelagica, Oucret, 1965; Aivariiio, 1969; Figueira,

1972; Owre, 1973.

Description. Length, to 28.2 mm; T%, 25-34; hooks, 7-10,

sharply curved at the tip; teeth, 13-22 or possibly more, according

to Figueira (1972). Ventral hook or hooks may be serrated on the

inner distal margin (Owre 1973). There is no collarette in the neck

region, but collarette-type epidermal tissue occurs from the level

of the anterior end of the ventral ganglion to the base of the caudal

fin. Corona ciliata has not been described. Eyes lack pigment.

Transverse musculature is well developed. Fins extend from a

level approximately at the middle of the ventral ganglion onto the

anterior half, more or less, of the caudal segment. Although in her

description, Aivariiio (1962) stated that there is no constriction of

the body at the caudal septum, some specimens have such a constriction (Fig. 10), which may result from muscular contraction at

death.

There are no intestinal diverticula. Mature ovaries may extend

through the posterior half of the trunk, although those of Caribbean specimens are much shorter. Owre's (1973) report of mature

ovaries in a 13 mm specimen suggests that there is more than one

period of maturation. Ovoid seminal vesicles develop just

posterior to the lateral fins and are broadly separated from the

caudal fin.

Distribution. Eukrohnia bathypelagica is a cosmopolitan mesobathypelagic species described from northern Pacific specimens

and since reported from the South China Sea (Alvariiio 1967), the

Gulf of Guinea (Oucret 1965), the North Atlantic near the Gulf of

St. Lawrence (Figueira 1972), the Caribbean Sea and Gulf of

Mexico (Owre 1973), and the Florida Straits (Stepien 1980).

Michel et al. (1976) collected it in waters 423 -2,118 m deep but

mainly in Subantarctic Intermediate Water, in the mesopelagic

realm (Table 3).

Eukrohnia fowleri Ritter-Zahony, 1909

Figure 11

Krohnia hamata, Fowler, 1905.

Krohnia hamata, Fowler, 1906.

Eukrohnia fowleri Ritter-Zahony, 1909.

Eukrohniafowleri, Ritter-Zahony, 1911 a, b; Oucret, 1965; Owre,

1960; Aivariiio, 1969; Michel, Foyo, and Haagensen, 1976;

Stepien, 1980.

14

Description. Length, to 40 mm; T%, 21-27; hooks, 8-13; teeth,

as many as 30. There is no collarette. The rounded apex of the

flask-shaped corona ciliata lies between the eyes and the base is

situated at the neck. The small pigmented area of the eye may be

elongated or triangular. Approximate extent of the lateral fins is

from the level of the middle of the ventral ganglion to the middle

of the caudal segment.
._-_... ",. --....-

5.0 11m

Figure ll.-Eukrohnia low/eri, dorsal view.

There are no intestinal diverticula. Mature ovaries are short,

with two rows of large ova. Gently curving, somewhat flattened

seminal vesicles develop just posterior to the lateral fins, well

anterior to the caudal fin.

Distribution. Cosmopolitan below 600 m in tropical and subtropical latitudes, this predominantly mesopelagic species has

been reported by Owre (1960) and Stepien (1980) from the

Florida Straits. Michel et al. (1976) found it only in Subantarctic

Intermediate and North Atlantic Deep Waters in the Caribbean

Sea, where it was collected between 635 and 2,104 m. Sagitta

macrocephala regularly occurred in the same samples.

Eukrohnia hamata (Mobius, 1875)

Figure 12

Sagitta hamata Mobius, 1875.

Krohnia hamata, Langerhans, 1880.

Eukrohnia hamata, Ritter-Zflhony, 1909, 1911 a, b; Ducret, 1965;

Owre, 1960; Alvariiio, 1969; Michel, Foyo, and Haagensen,

1976; Stepien, 1980.

Description. Length, to 43 mm, T%, 19-24; hooks, 8-10; teeth,

as many as 25. There is no collarette. The flask-shaped corona

ciliata extends onto the trunk. Eyes lack pigment. Lateral fins extend from the mid-level of the ventral ganglion onto at least the

anterior third of the caudal segment.

There are no intestinal diverticula. Ovaries are relatively

elongate, with small ova arranged in four rows, and the ovoid

seminal vesicles develop near the posterior end of the lateral fins

(Alvariiio, 1969). Specimens collected in lower Atlantic latitudes

rarely have reached advanced sexual development.

Distribution. This species has an Atlantic bipolar distribution,

with subtropical submergence, being epipelagic in the high latitudes and meso-bathypelagic in the lower ones (David 1958a;

Alvariiio 1964). Its distribution appears to be regulated mainly by

temperature. Owre (1960), noting Fowler's (1907) observation

that it had not been recorded from water warmer than 12.7°C,

reported it from 225-275 m in the Florida Straits, where the

temperature was well below 12°C. In the Caribbean, Michel et al.

(1976) found specimens at 715 m (7.2°C) and 822 m (6.5°C).

Stepien (1978) regarded its presence in deep currents (625-749

m), always colder than 7°C, in the Florida Straits as " ...strong

evidence for the presence of Atlantic waters originating in the

north" of the study area, due east of Miami, Fla. Having found no

trace of resident populations of E. hamata in the Caribbean,

Michel et al. (1976) speculated that it is an indicator of intrusions

of deep North Atlantic water.

5.0 mm

Figure 12.-Eukrohnia hamata, dorsal view.

15
Eukrohnia proboscidea Furnestin and Ducret, 1965

Figures 13, 14, 15

--=--

5.0 mm

Figure 13.-Eukrohnia proboscidea, dorsal view.

'r /

E

E

q

... e

e

q

....

Figure 14.-Eukrohnia proboscidea, dorsal view of head.

Eukrohnia proboscidea Furnestin and Ducret, 1965.

Eukrohnia proboscidea, Ducret, 1965; Owre, 1973; Michel. Foyo,

and Haagensen, 1976.

Description. Length, to 29.5 mm; T%, 20-31.2; hooks, sharply

curved at the tip, 10-13; teeth, 8-25. Owre (1973) reported that,

in the two smallest specimens she collected, measuring 13.0 and

16.5 mm, the ventralmost hook on each side bears 10-18 serrations on the inner margin. Projecting anteriorly on either side of

the distal midline of the head are two clearly separated groups of

"apical glands," a characteristic for which the species was named.

Eyes are distinguished by a very elongated pigmented area.

Although it was stated in the original description that no collarette

is present, a marked muscular constriction at the neck causes the

epidermis in that region to appear as a discrete layer. The corona

16

Figure 15.-Eukrohnia proboscidea, ventral view of head.

ciliata has not been described. Transverse musculature is well

developed. especially on the anterior trunk. Fins extend from the

level of the ventral ganglion onto the anterior half of the caudal

segment and are broadest posterior to the transverse septum.

There are no intestinal diverticula. Mature ovaries are short.

Ovoid seminal vesicles lie just posterior to the lateral fins,

separated by a distance approximately equal to their length from

the caudal fin.

Distribution. Eukrohnia proboscidea was described from 55

specimens collected at 1,000 and 1,100 m off southwest Africa.

Four specimens were found in Caribbean samples from 739,750.

1,100, and 2,072 m (Owre 1973; Michel et al. 1976). It is thus a

very poorly known species.
Bathybelos typhlops Owre, 1973

Figures 16, 17

5.0 mm

Figure 16.-8athybelos typhlops, dorsal view.

Description. Length, to 17.2 mm; T%, 29; hooks, 9-10; anterior

teeth, none; posterior teeth, 13. No traces of eyes or ventral

ganglion were found in the one specimen known, but a large rectangular nerve center is located on the dorsal side of the neck.

Neither collarette nor corona ciliata is present. Completely rayless

anterior and posterior lateral fins are short, evenly rounded, and

relatively thick at their bases.

There are no intestinal diverticula. The digestive tube appears

to be the type designated as simple by Dallot (1970). Mature

ovaries contain at least 10 ova and are approximately 4 mm long.

Seminal vesicles are separated from the caudal fin and probably in

contact with posterior lateral fins at maturity.

Dislribution. The one specimen known was collected from

2,500 m at lat. 25°59'N, long. 86°11 'w, in the western Gulf of

Mexico (Owre 1973).

E

E

o

.-:

Figure 17.-8athybelos typhlops, dorsal

view of head.

Sagitta bipunctata Quoy and Gaimard, 1827

Figure 18

Sagilla bipunctata Quoy and Gaimard, 1827.

Sagilla bipunctata, Ritter-Zahony, 1911 a, b; Aivariiio, 1969.

Description. Length, to 18.5 mm, usually to 15 mm in the southwestern North Atlantic; T%, 21-28; hooks, 8-10; anterior teeth,

5-8; posterior teeth, 8-16. Collarette is present on the posterior

head and anterior trunk, and a thinner layer of thickened epidermis may be observed on the trunk in undamaged specimens.

Aivariiio (1969) indicated by illustration that this thickening may

also be present between the posterior lateral fins and the seminal

vesicles. Corona ciliata as described by Ritter-Zahony (1911 a) is

..... attenuated, at least twice as long as the head, beginning close

behind the brain, mostly irregularly sinuous." The lateral fins contain rays throughout their lengths. The anterior pair extends to the

1.0 mm

Figure 18.-Sagitta bip"nctata, dorsal view.

17
posterior end of the ventral ganglion and is well separated from

the posterior pair, which is located approximately equally on

trunk and caudal segments.

There are no intestinal diverticula. Mature ovaries usually reach

the level of the anterior third of the anterior fins. Mature seminal

vesicles develop posterior to the terminus of the posterior fins and

extend to the caudal fin. This position and their shape, with a

knoblike protrusion at the anterior end, are diagnostic

characteristics.

Distribution. Sagitta bipunctata is a cosmopolitan oceanic

species in temperate and tropical waters. However, records from

the western North Atlantic indicate that it is far more numerous in

temperate waters, e.g., off Bermuda (Moore 1949; Pierrot-Bults

1982) than in tropical areas (Owre 1960; Michel et al. 1976).

Sagitta decipiens Fowler, 1905

Figure 19

Figure 19.-Sagitta decipiens, dorsal view.

Sagitta decipiens Fowler, 1905.

Sagitta sibogae, Fowler, 1906.

Sagitta decipiens, Ritter-Zilhony, 1911 a, b; Owre, 1960; Aivariiio,

1965, 1969; Michel, Foyo, and Haagensen, 1976.

Sagitta sibogae, Pierrot-Bults, 1979, 1982.

On the basis of specimens collected near Bermuda and alcoholpreserved type material, Pierrot-Bults (1979) concluded that S.

decipiens Fowler, 1905 and S. sibogae Fowler, 1906 are separate

species, the former being "deep-mesopelagic" and the latter,

"shallow-mesopelagic." The case for the acceptance of S. sibogae

as a valid species is not convincing at present, owing to the lack of

length-related meristic and other comparisons and the possibility

that the few differences mentioned may result from age, preservation, or variations associated with depth. Pierrot-Bults (1982) indicated that further information on S. sibogae is in preparation.

Meanwhile, the opinion of Ritter-Zilhony (l911a, b) that S.

sibogae is a synonym of S. decipiens is retained.

Description. Length, to approximately 20 mm; T%, 18-32;

hooks, 5-7; anterior teeth, 4-13; posterior teeth, 6-20. The imbricated arrangement of the short, triangular, anterior teeth in rows

which curve ventrad toward the midline is characteristic. The

collarette is so small that it usually is unobservable. Ritter-Zilhony

(1911a) illustrated an elongated, sinuous corona ciliata located

entirely on the anterior trunk, but this was a reconstruction as he

was able to observe only a portion of the structure. The shape of

the eye pigment is distinctive in adults. As Ritter-Zilhony (1911 a)

observed, it is rounded in small animals but gradually elongates

with growth until it becomes "T"-shaped, with a long lateral portion, oriented anteroposteriorly, and a short bar extending mediad.

Anterior fins may reach the posterior end of the ventral ganglion,

are relatively narrow, and are rayless anteriorly. Posterior fins are

similar but deltoid in shape.

The muscular walls of the pharynx, not shown in Figure 19, and

the intestinal diverticula are prominent. Mature ova are large, and

the ovaries may reach the level of the anterior one-third, approximately, of the anterior fins. Mature seminal vesicles are not in

contact with the lateral fins; their posterior tissues may extend to

the origins of the caudal fin.

Distribution. This is a mesopelagic species, cosmopolitan in

temperate and tropical latitudes. In the Caribbean region, Michel

et al. (1976) reported that numerically it ranked fourth among

chaetognaths, after S. enfiata, S. serratodentata, and Pterosagitta

draco. It occurs mainly between 200 and 1,000 m in Subtropical

Underwater and its mixture with North Atlantic Central Water,

and it is maximally abundant from 200 to 500 m. Pierrot-Bults

(1982) found S. decipiens most numerous between 500 and 600 m,

and S. sibogae, here considered a synonym, between 300 and 400

m, in waters near Bermuda. The materials on which Pierrot-Bults'

report is based are one day and one night series of samples collected from approximately the same depths.

Sagitta Enfiata Grassi, 1881.

Sagitta infiata, Ritter-Zilhony, 1908.

Sagitta enflata Grassi, 1881

Figures 2, 20

Sagitta enfiata, Fowler, 1906; Ritter-Zilhony, 1911 a, b; Aivariiio,

1965, 1969.

18
5.0 mm

Figure 20.-Sagilta enflaJa, dorsal view.

Description. Length, to 25 mm; T%, 14-17; hooks, 7-10;

anterior teeth, 3-8; posterior teeth, 4-17. Collarette is absent. Corona ciliata lies only on the head and, according to the illustration

by Ritter-Zahony (1911b), consists of anterior and posterior

loops, with a pair of smaller loops extending laterad from the base

of the anterior loop. Anterior and posterior fins are short. The

rounded anterior pair is situated far posterior of the ventral

ganglion, the posterior pair is deltoid, and rayless areas

characterize the inner portions of both.

There are no intestinal diverticula. Mature ovaries may extend

to the posterior portion of the anterior fins but usually are shorter.

Small, rounded seminal vesicles develop adjacent to the caudal

fin, distant from the posterior fins.

Distribution. Sagitta enflata is a common epipelagic species

worldwide in warmer waters. It is more abundant near land

masses than in the open ocean (Owre 1960), and, in the southeastern North Atlantic, it often is carried into neritic waters by

tidal movements. Pierce (1951) found a similar distribution in the

eastern Gulf of Mexico. An inhabitant of Tropical Surface Water

and upper Subtropical Underwater, it is the most numerous

oceanic chaetognath species in the Caribbean region and the Gulf

of Mexico (Michel et al. 1976).

Sagitta friderici Ritter-Ziihony, 1911

Figures 21, 22

1.0 mm

Figure 21.-Sagilta friderici, dorsal view.

Sagitta friderici Ritter-Zahony, 1911 a.

Sagitta friderici, Faure, 1952; Vannucci and Hosoe, 1952; Tokioka, 1955, 1961; Almeida Prado, 1961, 1968; LaguardaFigueras, 1967; McLelland, 1980.

Description. Length, to 13.5 mm; T%, 25-30; hooks, 7-9;

anterior teeth, 6-10; posterior teeth, 12-23. Collarette is present in

the neck region and on the upper trunk. Undulating, elongate corona ciliata extends from a level anterior to the eyes to a point

approximately two-thirds of the length between the neck and the

ventral ganglion (Tokioka 1961). The fins are supported throughout their extent by rays. The anterior fins extend to the posterior

end of the ventral ganglion. More of the posterior fin is situated on

the caudal segment than on the trunk, and it is broadest posterior

to the septum.

There are no intestinal diverticula. The ovaries are elongated

and, when fully developed, may extend to the level of the ventral

ganglion. The ova are small, numerous, and arranged in two or

19

e

e

It)

N

o

Figure 22.-Sagilta friderici, ventral view of head.
more rows. Mature seminal vesicles lie in proximity to both

posterior and caudal fins.

Distribution. Knowledge of the occurrence of this neritic species

in the Caribbean area is limited. Vannucci and Hosoe (1952)

reported it from Atlantic waters near Trinidad, and LaguardaFigueras (1967), from Laguna de Terminos in the southwestern

Gulf of Mexico. Mattlin (1974) found one specimen in a surface

sample from the Gulf of Cariaco (7.5 mm long, T% 30, hooks 8-8;

anterior teeth 7-7, posterior teeth 15-16, immature, with slight

development of seminal vesicles). In an important study of chaetognaths in the shelf and slope waters in the northeastern Gulf of

Mexico, McLelland (1978) collected S. friderici at all except one

station near the 200-fathom contour and reported that it was second in abundance, S. enflata being the most numerous species. It

.....showed a marked preference for lower salinity surface

waters... " and" ... was the dominant chaetognath in the upper

strata of the water column over the continental shelf...." It was

collected over a wide range of temperature and salinity but was

more commonly found in waters of< 34% 0 and> 23°C.

Sagitta friderici has not been reported from the east coast of

North America. In the Gulf of Mexico, it probably has often been

confused with the similar but smaller species, Sagitta tenuis. The

validity of S. friderici has been supported by numerous specialists,

among them Faure (1952) and Tokioka (1955,1961). However,

Tokioka (1974) has changed his opinion, stating, " ... tenuis and

friderici are very probably ecological forms of the single species

Sagitta tenuis; tenuis is the typical form of the species developed

limitedly in embayments in lower latitudes and of higher water

temperature (and probably salinity), while friderici is the form

developed in the open neritic waters of lower temperature (and

probably salinity, too). The distributional areas of these two forms

are adjoining each other." The fact that McLelland (1980) differentiated both species in his samples, the two occupying basically

the same habitat in the northeastern Gulf of Mexico, supports the

validity of S. friderici and demonstrates the need for further study

of populations of the two forms.

Sagitta helenae Ritter.Zahony, 1910

Figures 23, 24

1.0 mm

Figure 23.---Sagilla hetenae, dorsal view.

Sagitta helenae Ritter-Ziihony, 1910.

Sagitta helenae, Ritter-Ziihony, 1911 a, b; Pierce, 1951; Tokioka,

1955; Bumpus and Pierce, 1955; Owre, 1960; Pierce and Wass,

1962; Aivariiio, 1969.

Description. Length, to 15 mm; T%, 23-30; hooks, 6-8; anterior

teeth, 8-18; posterior teeth, 7-14. The number and arrangement of

the anterior teeth distinguish the species from immature Sagitta

hispida, a generally similar form. The bases of the teeth overlap,

and, as Pierce (1951) observed, in most preserved specimens they

extend away from the head, resembling a miniature curved fan.

Also, as pointed out here in the description of S. hispida, the form

of the eye pigment in S. helenae differs in being concentrated in a

smoothly ovoid area (Tokioka 1955). The conspicuous collarette

extends approximately halfway between the neck and the anterior

end of the ventral ganglion. Ritter-Ziihony (1911 a) described the

corona ciliata as elongated and slightly sinuous, reaching from the

region of the cerebral ganglia onto the trunk for a distance about

twice the length of the head. Both anterior and posterior fins are

supported by rays. The anterior pair lies just posterior to the ventral ganglion; the greater length of the posterior pair is divided

approximately equally by the transverse septum.

20

Figure 24.---Sagilla he/mae, ventral view of head.
There are no intestinal diverticula. Ripe ovaries may extend to

the level of the ventral ganglion according to Aivariiio (1969);

others have found them to be considerably shorter (Pierce 1951;

Tokioka 1955; present observations). Ovoid, mature seminal

vesicles, expanded at the anterior end, occupy most of the space

between lateral and caudal fins and are separated from the latter

by about one-seventh of their length (Tokioka 1955).

Distribution. This neritic species appears to be restricted to the

North Atlantic. It has been recorded from Delaware to the vicinity

of Key West, Fla., on the eastern seaboard of the United States.

Pierce and Wass (1962) found it to be numerous between the

approximate locations of Cape Hatteras, N.C., and Palm Beach,

Fla., and termed it a typical continental shelf species. It is also

common off the west coast of Florida south of the Cedar Key area

(Pierce 1951), in other parts of the Gulf of Mexico (Pierce 1954,

1962), and has been reported from the Cariaco Trench, Venezuela

(Legare and Zoppi 1961), and from Brazil (Alvariiio 1968). A few

specimens collected at stations within the Lesser Antillean Arc in

the Caribbean were regarded by Michel et al. (1976) as indicators

of strong coastal influence within the eastern Caribbean in the

fall, following the wet season in northeastern South America.

Sagitta hexaptera d'Orbigny, 1843

Figure 25

Figure 25.-Sagilla hexaplera, dorsal view.

Sagitta hexaptera d'Orbigny, 1843.

Sagitta hexaptera, Ritter-Zahony, 1911 b; Owre, 1960; Pierce and

Wass, 1962; Aivariiio, 1969; Stepien, 1980.

Description. Length, to 40 mm; T%, 17-20; hooks, 7-10;

anterior teeth, 2-4; posterior teeth, 2-6. The few, long, sharp,

anterior teeth, which usually project forward in preserved

specimens, are a distinctive feature. There is no collarette. The

pyriform corona ciliata lies entirely on the head just posterior to

the cerebral ganglia. Inner regions of both the short, rounded,

anterior fins and the longer, deltoid, posterior fins are rayless.

There are no intestinal diverticula. Ripe ovaries may extend to

the level of the ventral ganglion. Small, rounded, seminal vesicles

develop between lateral and caudal fins, slightly closer to the

latter.

Distribution. This easily recognized species occurs around the

world in temperate and tropical oceanic areas. Owre (1960)

reported that it was most numerous at approximately 100 m on

the western side of the Florida Current off Miami and 300 m on

the eastern side. In the Caribbean region, S. hexaptera occurs in

both Tropical Surface Water and Subtropical Underwater and is

collected primarily from the latter (Michel et al. 1976).

Sagitta hispida Conant, 1895

Figure 26

Sagitta hispida Conant, 1895.

Sagitta hispida, Pierce, 1951; Bumpus and Pierce, 1955; Tokioka,

1955; Suarez-Caabro, 1955; Legare and Zoppi, 1961; Almeida

Prado, 1968; Alvariiio, 1969.

Figure U.-Sagilla hispida, dorsal view.

21
Description. Length, to 14 mm; T%, 26-29; hooks, 6-9; anterior

teeth, 4-10; posterior teeth, 8-15. Measurements and counts of

hooks and teeth have been published by Conant (1895), Pierce

(1951), Sufuez-Caabro (1955), Tokioka (1955), and Legare and

Zoppi (1961). It should be noted that the measurements of total

length in the latter two publications include the caudal fin.

Pierce (1951) and Tokioka (1955) redescribed this stout, largeheaded species, which is characterized by a thick collarette in the

neck region and an elongate corona ciliata, extending from a point

anterior to the eyes posteriorly onto the trunk, ending short of the

ventral ganglion. The numerous sensory hairs, which are arranged

in species-specific hair-fan patterns (Feigenbaum 1978), give the

body the hispid appearance from which the name was derived.

Both pairs of lateral fins are supported throughout by rays. The

anterior fins extend to the ventral ganglion. The posterior fins,

broadest behind the transverse septum, reach the seminal vesicles,

which are widely separated from the caudal fin.

Tokioka (1955) illustrated differences in the eye pigment of

Sagitta helenae and S. hispida, species which may occur in the

same area and are similar in general appearance until sexual

maturity is attained. These differences have consistently served as

convenient characteristics to separate immature forms. In S.

helenae, the pigment is concentrated in a uniformly black,

smoothly ovoid spot. In S. hispida, this area is slightly concave

laterad, and the pigment appears concentrated in a band along the

concave margin. At approximately the middle of the band, a

shorter band extends mediad at right angles to it. The black pigment is thus concentrated in a T-shaped area, and the remainder

of the ovoid spot is less densely pigmented.

Intestinal diverticula are present. Fully formed ovaries virtually

fill the trunk coelom. The seminal vesicles are broadly expanded

at the anterior end and, in mature specimens, also have a second,

more posterior bulge. For extensive information about the reproduction of this species, as well as other aspects of its biology, the

reader is referred to the works of Reeve (1964a, b, 1966, 1970a,

b), Reeve and Cosper (1975), Reeve and Lester (1974), and Reeve

and Walter (I 972a, b).

Distribution. Since its description by Conant, from specimens

collected off Beaufort, N.C., S. hispida has been erroneously

reported from many parts of the world. It is an Atlantic species,

abundant and widely distributed in temperate and tropical coastal

waters of islands as well as continents (Pierce 1951; Tokioka

1955; Owre 1960; Legare and Zoppi 1961; Almeida Prado 1968;

Owre 1972b; Owre and Foyo 1972; Michel et al. 1976;

McLelland 1978). Alvarifio (1965, 1969) illustrated its distribution as trans-Atlantic, with latitudinal extremes of approximately

34°N and 30oS. As Reeve (I 970a) stated, "There appears to be

considerable doubt as to its occurrence, at least in any numbers, in

mid-Atlantic waters...." A plot of records listed in Alvarifio's

1969 work shows that the collections were made near land, with a

few exceptions in areas off northeastern South America and east

of the Lesser Antilles where outflow from the Amazon and

Orinoco Rivers strongly influences the distribution of planktonic

organisms. Specimens could also be transported from northwestern Africa to these areas by the North Equatorial Current.

Although S. hispida has been collected occasionally in the Florida

Straits 10 mi east of Miami and even 40 mi east, Owre (1960)

concluded that its presence indicated mixing of neritic and

oceanic waters. Those occurring at the former location may have

originated in coastal waters of the Gulf of Mexico or Cuba. The

site 40 mi east of Miami is near the shallow waters of the western

Bahamian island chain, where S. hispida is extremely abundant.

One specimen reported from 685 m has been considered a contaminant since all of our knowledge of its vertical distribution

shows it to be an epiplanktonic species. However, Stepien (1978),

who collected it at 681 and 685 m at a site farther west in the

Straits, regarded it as an indicator of entrained surface waters.

Sagitta lyra Krohn, 1853

Figure 27

Sagitta lyra Krohn, 1853.

Sagitta lyra, Ritter-Zflhony, 1911a, b; Germain and Joubin, 1916;

Moore, 1949; David, 1955; Owre, 1960; Alvarifio, 1969.

Description. Length, to 42 mm; T%, 14-28, usually 14-18;

hooks, 3-11; anterior teeth, 2-8; posterior teeth, 2-12. Data on

some large Caribbean specimens collected at 1,000 m (Michel et

al. 1976: Cruise P 6911, Station 7) are:

Length

(mm)

30

25

25

24

T%

28

16

16

17

H

4-4

4-4

4-4

6-6

Ta

3-3

5-5

7-7

4-5

Tp

4-4

3-3

3-3

5-5

Figure 27.--Sagitta lyra, dorsal view. The Indentation in the posterior margin of the caudal fin is an artifact.

22
Sagitta lyra resembles S. enflata and S. hexaptera in its relatively

broad, weakly muscled body. It is distinguished by a bridge of rayless, epidermal tissue which connects the anterior and posterior

lateral fins. Both pairs of fins have rays in the outer portion, and in

the anterior pair, these are found only in the posterior part. The

anterior fins extend to, or nearly to, the ventral ganglion.

The species lacks a collarette, according to Ritter-Ziihony

(191la, b). However, a small collarette is present in Caribbean

specimens, and this feature has also been noted in specimens from

the eastern North Atlantic and the Mediterranean (Casanova

1977). Aivariiio (1962), in her original description of S. scrippsae,

pointed out that it has a collarette, whereas S. lyra does not.

Casanova (1977) obtained specimens of S. scrippsae to compare

with S. lyra, and he concluded that the former is a subspecies of

the latter.

Mature animals have seldom been found in our collections.

According to Ritter-Zlihony (191Ia), the ovaries may extend as

far as the middle of the anterior lateral fins; Aivariiio (1969)

showed them reaching the anterior third of these fins. There is a

marked constriction of the body just posterior to the seminal

receptacles, at the level of the transverse septum. The small,

rounded, seminal vesicles are situated midway between the

posterior lateral and caudal fins.

Distribution. Sagitta lyra is a mesopelagic oceanic species which

is cosmopolitan in warm and temperate latitudes. It has been collected in Tropical Surface Water, where it is an indicator of

upwelling, Subtropical Underwater, Subantarctic Intermediate

Water, and North Atlantic Deep Water, but the majority of the

populations lives in the two intermediate water masses (Michel et

al. 1976).

Sagitta macrocephala Fowler, 1905

Figures 28, 29

Figure 28.-Sagitta macrocephala, dorsal view.

Sagitta macrocephala Fowler, 1905.

Sagitta macrocephala, Ritter-Ziihony, 1911a, b; Owre, 1960; AIvariiio, 1969; Stepien, 1980.

Description. Length, to 22 mm; T%, 29-36; hooks, 10-12;

anterior teeth, 6-10; posterior teeth, 17-38. The large, rectangular

head and numerous brown hooks and teeth are distinctive

features. There is no collarette. The corona ciliata has not been

described; Ritter-Ziihony (191la) suggested that it is destroyed

during the long period between the capture of this deep-living

species and its preservation. The eyes lack pigment. The short

anterior fins, located posterior to the ventral ganglion, are fully

rayed. The much longer and broader posterior fins also contain

rays except for an inner area which extends to and includes the

anterior portions of these fins.

There are no intestinal diverticula. Ripe ovaries may extend to

the level of the ventral ganglion, according to Aivariiio (1969).

Ovoid seminal vesicles are not in contact with either lateral or

caudal fins but develop closer to the former than to the latter.

Mature specimens have rarely been collected in the area considered here.

Distribution. This species, generally described as cosmopolitan

and mesopelagic, has been reported from the Antarctic and the

Subantarctic, and from the Atlantic, Pacific, and Indian Oceans.

Owre (1960) found only two individuals in collections from the

23

[rlgure 29.-Sagitta macrocephala, venlral view of bead.
Florida Straits but it was common in Stepien's (1980) samples.

More extensive sampling in the Caribbean region showed that it is

widely distributed in both mesopelagic and bathypelagic realms

and restricted to Subantarctic Intermediate and North Atlantic

Deep Waters (Michel et al. 1976).

Sagitta megalophthalma Dallot and Ducret, 1969

Figures 30, 31, 32, 33

1.0 mm

Figure 30.-Sagitta mega/aphtha/ma, dorsal view.

1.0 mm

Figure 31.-Sagitta mega/ophtha/ma, Immature, dorsal view.

Sagitta megalophthalma Dallot and Ducret, 1969.

Sagitta megalophthalma Michel, Foyo, and Haagensen, 1976;

Stepien, 1980.

Description. Length, to 21 mm or more; T%, in the largest

individuals, approximately 23.5; hooks, 7-8; anterior teeth, as

many as 10; posterior teeth, as many as 18. Collarette is well

developed, situated in the neck region and on the anterior trunk.

Corona ciliata is narrow, sinuous, and elongated, beginning just

anterior to the level of the eyes and extending to a point about

halfway between the cephalic septum and the ventral ganglion.

Eyes (Fig. 33) are diagnostic because of the large pigmented area,

the general configuration of which is rectangular, and the

divergence of the longitudinal axes of these areas to form an angle

of approximately 45°, opening anteriorly. Very fine rays are

found throughout the pairs of lateral fins. The anterior fins

originate posterior to the ventral ganglion, from which they are

separated by a distance equal to approximately half its length, and

they are well separated from the slightly longer posterior fins.

There are no intestinal diverticula. A portion of the intestine,

about two-thirds of the total length of the digestive tube, is

characterized by conspicuous vacuolar cells. Dallot and Ducret

(1969) did not believe that they had observed completely mature

ovaries, nor has the writer. Mature ovaries containing rounded ova

probably extend at least to the region of the anterior end of the

posterior lateral fins. The ovoid seminal vesicles develop well

posterior to the lateral fins and are separated by a lesser distance

from the base of the caudal fin.

24

E

E

10

o

Figure 32.-Sagitta mega/ophtha/ma, ventral view of head.
a b

e

e

""'=

o

Figure 33.-Sagitta megalophthalma, left (a) and right (b) eyes.

Distribution. Sagitta megalophthalma was described from

specimens collected between 100 and 700 m in the western Mediterranean; additional material from the Tyrrhenian Sea and the

Gulf of Guinea contributed to knowledge of the species (Dallot

and Ducret 1969). Michel et al. (1976) reported a few individuals

in samples from the Caribbean Sea. Specimens collected by Mattlin (1974), most from the upper 50 m, in the Cariaco Trench were

identified by the writer as S. megalophthalma. Stepien (1980) and

Cheney (1982, footnote 4) found a few in the Florida Straits and

the northwest North Atlantic, respectively. This distinctive

species remains so poorly known that it is possible only to speculate on its distribution. In the North Atlantic, it appears to be an

upper mesopelagic species which may be entrained to shallower

water. Michel et al. (1976) suggested that it may be an indicator of

water movement from the North Atlantic into the Caribbean Sea.

4J. Cheney, Postdoctoral appointment. Institute of Oceanography, Dalhousie

University, Halifax, Nova Scotia, Canada, pers. commun. May 1981.

Sagitta Minima Grassi, 1881

Figure 34

Sagitta Minima Grassi, 1881.

Sagitta minima, Ritter-Ziihony, 1911 a; Pierce, 1953, 1962; Owre,

1960; Alvariiio, 1969.

Description. Length, to 9 mm; T%, 17-24; hooks, 7-9; anterior

teeth, 2-5; posterior teeth, 6-14. There is no collarette. Corona

ciliata is an elongate oval in shape and is located on the anterior

trunk (Ritter-Ziihony 1911a). The anterior and posterior pairs of

fins contain rays in their outer portions but the fins are so fragile

that these areas may be lost. The anterior pair is particularly hard

to see. The posterior fins lie mainly on the trunk. The body of this

small species may be flaccid owing to the effects of capture and

preservation.

Intestinal diverticula are present, and, posterior to them, the

digestive tube is the vacuolar type described by Dallot (1970). The

short, club-shaped, mature ovaries hardly extend past the middle

of the posterior fins. The elongated seminal vesicles develop adjacent to the caudal fin, lying far posterior to the lateral fins.

1.0 mm

Figure 34.-Sagi//a minima, dorsal view.

25
Distribution. Sagitta mInima is a cosmopolitan, epipelagic

species, which, in the southwestern North Atlantic and the Florida

Straits, is found in greatest numbers in oceanic water at the edge

of the continental shelf (Owre 1960; Pierce and Wass 1962). It

has also been reported from the Caribbean and adjacent areas by

Prado (1961), Mattlin (1974), and Michel et al. (1976).

Sagitta planctonis Steinhaus, 1896

Steinhaus (1896) described S. planctonis from specimens collected in shallow tows in the Atlantic South Equatorial Current. A

similar species, S. zetesios, was described from deep water in the

Bay of Biscay by Fowler (1905). Sagitta zetesios was synonymized

with S. planctonis by Ritter-Zahony (191la), and other workers

agreed until specimens subsequently collected revived the problem of distinguishing the two forms. David (1956) concluded

that S. zetesios is a valid species. Aurich (1971) and Pierrot-Bults

(1969, 1970, 1975) have worked extensively with North Atlantic

specimens, reporting the presence of intermediates in collections

containing both species and analyzing latitudinal and vertical distribution. After making factor and discriminant analyses, PierrotBults (1975) decided that this is a polytypic species composed of

the formae planctonis and zetesios. The specimens that Moore

(1949) reported from the shallow waters in the Bermuda area as S.

planktonis, and identification confirmed by F. S. Russell and J. W.

S. Marr, were probably strays of S. planctonis forma planctonis,

although both formae and the intermediates occur there. PierrotBult's (1975) data for the latitude of Bermuda indicate that the

intermediates and forma zetesios do not occur in the upper 300 m.

Both formae have been collected in the regions considered herein,

planctonis being rare and zetesios more numerous.

Sagitta planctonis forma planctonis Steinhaus, 1896

Figure 35

5.0 mm

Figure 3S.-Sagilta planelonis formaplanetonis, dorsal view.

Sagitta planctonis Steinhaus, 1896.

Sagitta planctonis, Fowler, 1905, 1906; Tokioka, 1940; Thomson,

1947; David, 1956; Colman, 1959; Owre, 1960.

Sagitta planktonis, Michael, 1911; Moore, 1949.

Sagitta planctonis forma planctonis, Pierrot-Bults, 1975.

Description. Length, to 37 mm; T%, 19-23; hooks, 6-11, usually

8-11; anterior teeth, 5-9, usually 6-8; posterior teeth as many as

14, usually 10-12. Collarette is prominent, extending at least to

the level of the anterior fins and, according to David (1956), even

to the tail in fully grown specimens. Corona ciliata, as described

by David (1956) from the illustration by Tokioka (1940), begins

on the posterior part of the head and extends to a point about

halfway between head and ventral ganglion. Anterior fins, which

may extend to the level of the middle of the ventral ganglion, lack

rays in inner and anterior portions. Triangular posterior fins, with

the rays limited to the outer portions, are broadest at approximately the level of the transverse septum.

Intestinal diverticula are present. Fully mature ovaries fill the

trunk coelom. The anteriorly rounded, elongate seminal vesicles

are located next to the posterior fins and are separated from the

caudal fin.

26

Distribution. David (1956) attempted to clarify the anomalous

distribution of this species, showing that there are three species

previously recognized as one: S. planctonis is "epiplanktonic" in

warm waters, S. zetesios lives in deep oceans, except for the Antarctic, and S. marri David 1956, is probably endemic to the Antarctic. Moore's (1949) perplexity at the shallow habitat of S.

planctonis off Bermuda was thus explained by David, who recorded its distribution as "Bermuda, S.E. Africa, (Aghulas current

area), Tasman Sea, off N.E. New Zealand, and parts of N. Atlantic.

A surface living form breeding at a moderate depth (1000-750

m)." Pierrot-Bults (1975) has since shown that S. planctonis forma planctonis occurs over a range of approximately 100-1,000 m

between lat. 45°N and 400 +S in the Atlantic Ocean.

Colman (1959) collected two specimens in tows made with

open nets, from 900 and 1,000 m, in the area between St. Paul's

Rocks and the west coast of Africa. Owre (1960) found only two

specimens in samples from the Florida Straits, at approximately

150 and 730 m, a record listed by Aivariiio (1965) as S. zetesios,

with a question mark. One specimen was found by Michel et al.

(1976) in a Caribbean sample from 739 m, in Subantarctic Intermediate Water. Its occurrence in the Caribbean and the Florida

Straits probably indicates the presence of North Atlantic Central

Water as well as SAIW.
Sagitta planctonis forma zetesios Fowler, 1905

Figures 3, 36

I

\ '-

5.0 mm

Figure 36.--Sagitta planetonis forma zetesios, dorsal view.

Sagitta zetesios Fowler, 1905.

Sagitta zetesios, Fowler, 1906; Michael, 1911.

Sagitta planctonis, (non Steinhaus), Ritter-Zilhony, 1911a (partim); Germain and Joubin, 1916; Tokioka, 1939; Fraser,

1952.

Sagitta zetesios, David, 1956; Colman, 1959; Alvarifio, 1967.

Sagitta planctonis forma zetesios, Pierrot-Bults, 1975.

Description. Length, to 43 mm; T%, 20-26; hooks, 8-11;

anterior teeth, 6-12, usually 8-10; posterior teeth, 10-22. Collarette is prominent, extending at least to the level of the anterior fins

and, according to David (1956), even onto the tail in large

specimens. Corona ciliata is elongated, beginning on the neck and

extending toward the ventral ganglion. Anterior fins reach the

level of the posterior end of the ventral ganglion and have few or

no rays in the anterior portion. Posterior fins are triangular, with

the apex approximately coinciding with the transverse septum.

Refer to the description of forma planctonis for additional information about the fins.

Intestinal diverticula are present. Mature ovaries may extend to

the ventral ganglion. As in forma planctonis, the elongate, rounded, seminal vesicles are situated next to the posterior fins and are

well separated from the caudal fin.

Immature specimens of 20 mm and less lack the extensive

collarette of larger forms; it is confined to the region of the neck.

The presence of diverticula and an intestine of Dallot's (1970)

type 2, with many vacuolar cells, aid in identification. Although

the posterior teeth in mature specimens regularly number more

than 14, smaller individuals have fewer teeth. Data on 10 immature specimens are given in Table 5.

Distribution. David (1956) described this as a deep-living form

found in most oceans but absent from the Antarctic. In the Atlantic, Colman (1959) collected it from approximately 750 to 1,300

m, at stations extending from the waters off S.W. Greenland to

Brazil. Aurich (1971) and Pierrot-Bults (1975) have shown that

the distribution of forma zetesios extends into the upper 150 m in

North Atlantic cold-temperate waters, and that it gradually

deepens in the lower latitudes. In the areas considered here, between approximately lat. 35° and lOON, it has an overall range of

about 400 to 1,250 m, according to Pierrot-Bults (1975).

Although forma zetesios was never numerous in Caribbean

samples, Michel et al. (1976) found it widely distributed both

horizontally (" ... caught in nearly every part of the Caribbean ... ") and vertically (from 38 m in the Windward Passage to

3,000 m in the Colombian Basin of the central Caribbean). Stepien (1978) collected one specimen in the Florida Straits at 687

m. Both formae of S. planctonis probably indicate intrusion of

North Atlantic water in the Caribbean and adjacent areas. If

reproducing populations existed there, they would probably have

been sampled by now.

Table 5.-Measurements and counts of teeth of immature Sagitta planetonis forma zetesios.

Length

(mm) T% H Ta Tp Station' and depth

9.5 26.0 9-9 7-7 13-1 P6911, Stn. 4,423 m

9.5 26.0 10-10 6-6 10-12 P691 I, Stn. 4,423 m

10.0 25.0 8-8 1-16 P6805, Stn. 4,500 m

12.0 26.0 9-10 5-6 P6911, Stn. 4,423 m

12.2 24.5 8-8 8- 1 13-11 P6805, Stn. 4,500 m

15.0 25.0 9-9 7-1 17-17 P6805, Stn. 4,500 m

16.5 24.0 9-9 8-8 15-16 P6911, Stn. 7,779 m

17.0 23.5 8-9 8-9 15-15 P6805, Stn. 10,477 m

19.3 24.0 9-9 9-10 15-1 P6911, Stn. 3,494 m

20.0 23.5 P6911, Stn. 3,494 m

'P6805, Stn. 4, 19°02'N, 800 20'W; P6805, Stn. 10, 14°32'N, 68°II'W;

P6911, Stn. 3, 15°00'N, 62°00'W; P6911, Stn. 4, 14°15'N, 61°40'W;

P6911, Stn. 7, 15°01'N, 64°32'W (Michel et a1. 1976).

Sagitta serratodentata Krohn, 1853

Figures 37, 38

Sagitta serrato-dentata Krohn, 1853.

Sagitta serratodentata, Ritter-Zilhony, 1911 a, b; Owre 1960;

Pierce and Wass 1962; Grant, 1967; Alvarifio, 1969; Stepien,

1980.

27

Description. Length, to 15 mm; T%, 20-28; hooks, 6-7; anterior

teeth, to 11; posterior teeth, to 20. The inner margins of the hooks

are serrated, usually not as coarsely as illustrated in Figure 38. A

short collarette can be observed in the neck region. The elongate,
1.0 mm

Figure 37.-Sagitta serratotkntala, dorsal view.

sinuous corona ciliata extends from an area just posterior to the

cerebral ganglia onto the trunk for a distance at least twice the

length of the head. Both pairs of the long lateral fins have a small

inner rayless area. The anterior pair originates just posterior to the

level of the ventral ganglion.

There are no intestinal diverticula. Mature ovaries may reach

the level of the anterior end of the anterior fins. Seminal vesicles,

even before maturity, have a distinctive shape, in that a membranous supporting structure extends from the lateral fins to the

anterior portion of each vesicle, producing a deltoid appearance.

Anteriorly, mature vesicles are characterized by a pair of clawlike

projections.

Distribution. Sagitta serratodentata is a common, epipelagic,

oceanic species in subtropical and tropical waters of the North

Atlantic. It has also been reported from the Pacific and Indian

Oceans and the Mediterranean Sea. Grant (1967) analyzed its

distribution compared with the similar S. tasmanica in the North

Atlantic. Owre (1960) observed that, in the Florida Straits off

Miami, it was second to S. enflata in abundance on the western

side but the most abundant species at the eastern station. In the

Caribbean and the Gulf of Mexico, it is found in both Tropical

Surface Water and Subtropical Underwater and is most numerous

in the former (Michel et al. 1976).

e

e

It)

<"I

d

Figure 38.- Sagitta .."alodentala, ventral view of head.

Sagitta tenuis Conant, 1896

Figure 39

Sagitta tenuis Conant, 1896.

Sagitta tenuis, Pierce, 1951; Faure, 1952; Tokioka, 1955; Bumpus

and Pierce, 1955; Legare and Zoppi, 1961; Alvarifio, 1969;

Owre and Foyo, 1972; McLelland, 1980; Stepien, 1980.

Description. Length, to 8.2 mm; T%, 25-29; hooks, 7-9; anterior

teeth, 4-7; posterior teeth, 7-17. A thin collarette is present in the

neck region. Corona ciliata is about 2.5 times the length of the

head (Tokioka 1955). Eye pigment forms a spot almost exactly

1.0 mm

Figure 39.-Sagitta tenuis, dorsal view. The Indentation In the posterior margin of the caudal fin is an artifact.

28
square in shape, in contrast to the oval form illustrated by Tokioka

(1955). Lateral fins are similar to those of S. friderici, completely

set with rays. However, the anterior fins may not extend as far

anteriorly as the ventral ganglion.

There are no intestinal diverticula. Ripe ovaries contain large

ova arranged in a single row. As many as 15 ova have been

counted in each ovary of a mature specimen. The ovaries usually

do not extend beyond the anterior edge of the posterior fins

although they may swell slightly beyond this level. The thin,

elongate seminal vesicles lie between the posterior and caudal

fins, reaching them both at maturity, and are bulbous in the

anterior portion.

Distribution. The broad latitudinal range of this eurythermal,

euryhaline, neritic species was disr.ussed by Owre and Foyo

(1972), who noted that it had been reported from Delaware to

Brazil in waters of 3.5°-27.5°C and 10.9-39.7% °' McLelland

(1978) made an interesting report of its cooccurrence with S.

friderici in the northeastern Gulf of Mexico. It was third in abundance after S. friderici and S. enflata and was most numerous in

salinities of 30.0-35.9% 0 and temperatures of 26.0o-30.3°C.

Although common in other parts of the Gulf of Mexico, including

waters off the west coast of Florida, it has rarely been reported

from the east coast of Florida south of Salerno, in the vicinity of

Cape Canaveral. Recently, Barbara K. Sullivan, while working at

Harbor Branch Foundation, Inc., Ft. Pierce, Fla., collected a few

specimens in the Indian River lagoon and also in coastal Atlantic

water east of the Ft. Pierce Inlet, areas where S. hispida is the

dominant form. North of Cape Canaveral, it becomes a numerous

component of the nearshore plankton as far as the latitude of

Delaware (Grant 1963a). The presence of S. tenuis in a sample

from 691 m in the Florida Straits off Miami was regarded by Stepien (1980) as an indication that coastal water contributes to the

countercurrent beneath the Florida Current.

Pterosagitta draco (Krohn, 1853)

Figure 5

Sagitta draco Krohn, 1853.

Pterosagitta mediterranea, A. Costa, 1869.

Spadella draco, Langerhans, 1880; Fowler, 1906; Ritter-Zahony,

1910.

Pterosagitta draco, Ritter-Zahony, 191 I a.

Pterosagitta besnardi, Vannucci and Hosoe, 1952.

Pterosagitta draco, Owre, 1960; Tokioka, I 965a; Alvariiio, 1965,

1969.

Description. Length, to 10.5 mm; T%, 38-46; hooks, 8-10;

anterior teeth, 5-9; posterior teeth, 8- I 8. The prominent collarette, which extends the length of the body, is most noticable on the

trunk. In perfectly preserved specimens, a pair of long, V-shaped

"hair-fans" can be seen on either side of the anterior third of the

collarette. These are not the only epidermal structures on the

collarette, but they are exceptionally long and, in the literature,

have been called "wings." Bieri (1966) observed and experimented with these tufts in a living specimen, and he postulated

that they serve as detectors of water motion. The collarette is often

nearly or entirely destroyed during collection by net. The oval,

elongate corona ciliata is located on the anterior trunk, beginning

in the region of the neck (Ritter-Zahony, 1911 b). One pair offully

rayed, rounded lateral fins originates at the transverse septum and

extends to the seminal vesicles.

There are no intestinal diverticula. When mature, the ovaries

may fill the trunk coelom to the septum between head and trunk,

and the seminal vesicles extend between the lateral and caudal

fins.

Distribution. This is an epipelagic oceanic species, cosmopolitan in temperate and tropical waters, and often reported from

the western North Atlantic and adjacent areas (Alvariiio 1969). In

the Caribbean Sea and the Gulf of Mexico, it is among the most

numerous forms and is maximally abundant in the upper 100 m

(Michel et al. 1976).

Krohnitta pacifica (Aida, 1897)

Figure 40

Krohnia pacifica Aida, 1897.

Eukrohnia pacifica, Michael, 191 I.

Krohnitta pacifica, Tokioka, 1939, 1940, 1942; Thompson, 1947;

Pierce, 1951, 1953, 1954, 1958, 1962; Suarez-Caabro, 1955;

Owre, 1960; Legare and Zoppi, 1961; Aivariiio, 1963, 1965,

1967.

Figure 40.--Krohnitta pacifica, dorsal view.

29
Krohnitta subtilis (partim), Ritter-Zahony, 1910, 1911 a.

Krohnitta mutabbii, Aivariiio, 1969.

Krohnitta pacifica, Owre, 1973.

Description. Length, to approximately 7.5 mm; T%, 26-31;

hooks, 7-10; teeth, 11-16. The corona ciliata originates in the

mid-dorsal region just posterior to the eyes, extends to its greatest

width on the neck, and then tapers to its termination on the

anterior part of the trunk (Ritter-Zahony 1911 a; Suarez-Caabro

1955). The lateral fins usually contain rays in the outer portion,

from the anterior to the posterior end, and have an inner rayless

area of variable extent.

There are no intestinal diverticula. Mature ovaries extend well

beyond the anterior extremity of the lateral fins and may reach the

vicinity of the ventral ganglion. The oval seminal vesicles are in

contact with both caudal and lateral fins.

Records indicate that Indo-Pacific specimens having hook and

tooth counts similar to Atlantic forms may be longer, with a proportionately larger caudal segment (e.g., 6-9 mm, 29-36 T%,

Thompson 1947; 4.2-7.2 mm, 28.1-37.5 T%, Sund 1959; 6-8

mm, 27 -34 T%, Aivariiio 1967). Aivariiio (1969) proposed the

new species K. mutabbii for the Atlantic forms; Owre (1973) put

this name in synonymy on the grounds that sufficient differences

to erect a new species had not been demonstrated.

Distribution. Originally believed to be an Indo-Pacific species,

K. pacifica has been reported many times from the western North

Atlantic and the Gulf and Caribbean areas (e.g., Pierce 1951,

1953,1954,1958,1962; Pierce and Wass 1962; Suarez-Caabro

1955; Suarez-Caabro and Madruga 1960; Owre 1960; Legare and

Zoppi 1961; Michel et al. 1976; McLelland 1978). Michel et al.

(1976) reported that it is found primarily in the upper 200 m, in

Tropical Surface Water and Subtropical Underwater.

Krohnitta subtiUs (Grassi, 1881)

Figures 4, 41

Figure 41.-Krohni/la sublilis, dorsal view.

Sagitta Suptilis (sic) Grassi, 1881.

Spadella Subtilis, Grassi, 1883.

Krohnia subtilis, Fowler, 1905, 1906.

Eukrohnia subtilis, Michael, 1911.

Krohnitta subtilis (partim), Ritter-Zahony, 1911 a.

Krohnitta subtilis, Suarez-Caabro, 1955; Owre, 1960; Aivariiio,

1969.

Description. Length, to approximately 16 mm; T%, 30-40;

hooks, 6-9; teeth, 10-13. Corona ciliata is approximately deltoid,

about as long as the head, and lies on an area between the anterior

trunk and a point posterior to the eyes (Ritter-Zahony 1911 a, b;

Suarez-Caabro 1955). The broad lateral fins contain rays in their

outer portions, with about one-third of their extent situated on the

trunk and the remainder on the caudal segment.

There are no intestinal diverticula. Mature ovaries rarely extend

beyond the anterior edge of the lateral fins. Oval mature seminal

vesicles are in contact with both caudal and lateral fins.

Distribution. Krohnitta subtilis is primarily mesoplanktonic in

the Caribbean area but has been collected from lower Tropical

Surface Water through Subtropical Underwater (Michel et al.

1976; Tables 2, 3). It has been reported from the Florida Straits

(Owre 1960; Stepien 1980), Cuban waters (Suarez-Caabro 1955),

the Gulf of Mexico (Pierce 1962; McLelland 1978), the north

Atlantic off Trinidad (Vannucci and Hosoe 1952), and from the

Amazon area (Alvariiio 1968).

ACKNOWLEDGMENTS

The sampling program in the Caribbean, including the use of

ships, was supported by the National Science Foundation with

Grants GB-3808, GB-5776, GB-7082, GA-4569, GB-5625, and

GB-13113 until the termination of the last in April 1970. Examination of samples continued with the support of ONR Contract N

0014-67-A-0201-0013, and this report was prepared in part during the ONR contract period.

30

I am grateful to Robert Bieri of Antioch College, Yellow

Springs, Ohio, and to M. R. Reeve of the University of Miami for

reviewing the manuscript, and to Kathy Wilson, Susan Suarez,

and Steven Hess for preparing the illustrations, which were drawn

from preserved specimens.
LITERATURE CITED

AHLSTROM, E. H., and J. R. THRAILKILL.

1962. Plankton volume loss with time of preservation. Rapp. P.-V. Reun.

Cons. Int. Explor. Mer 153:78.

AIDA, T.

1897. Chaetognaths of Misaki Harbor. Annot. Zool. Jpn. 1:13-21.

ALMEIDA PRADO, M. S. de.

1961. Distribucao dos Chaetognatha no Atlantico suI Ocidental. Bolm. Inst.

Oceanogr. S. Paulo 12: 15-49.

1968. Distribution and annual occurrence of Chaetognatha off Cananeia and

Santos Coast (Sao Paulo, Brazil). Bolm. Inst. Oceanogr. S. Paulo 17:33-55.

ALVARINO, A.

1962. Two new Pacific chaetognaths. Bull. Scripps Inst. Oceanogr. 8:1-50.

1963. Quetognatos del Mar de Cortes: parte sistematica. Rev. Soc. Mex.

Hist. Nat. 24:97-203.

1964. Bathymetric distribution of chaetognaths. Pac. Sci. 18:64-82.

1965. Chaetognaths. Oceanogr. Mar. BioI., Annu. Rev. 3:115-194.

1967. The Chaetognatha of the Naga Expedition (1959-1961) in the South

China Sea and the Gulf of Thailand. Naga Rep. 4: 1-197.

1968. Los quetognatos, sifonoforos y medusas en la region del Atlantico ecuatorial bajo la influencia del Amazonas. An. Inst. BioI. Univ. Nac. Auton.

Mex., 39, Ser. Cienc. Mar y Limnol. (1):41-76.

1969. Los quetognatos del Atlantico. Distribucion y notas esencia1es de

sistematica. Trab. Inst. Esp. Oceanogr., No. 37, Madrid, 290 p.

1970. A new species of Spadella (benthic Chaetognatha). Stud. Fauna

Curacao Other Caribb. lsI. 34:73-89.

AURICH, H. J. von.

1971. Die verbreitung der Chaetognathen im gebiet des Nordatlantischen

Strom-Systems. Ber. Dtsch. Wiss. Komm. Meeresforsch. 22:1-30.

BEKLEMISHEV, V. N.

1969. Principles of comparative anatomy of invertebrates. I. Promorphology.

Oliver and Boyd, Edinburgh, 490 p.

BIERI, R.

1959. The distribution of the planktonic Chaetognatha in the Pacific and

their relationship to the water masses. Limnol. Oceanogr. 4:1-28.

1966. The function of the "wings" of Pterosagilla draco and the so-called

tangoreceptors in other species of Chaetognatha. Publ. Seto Mar. BioI. Lab.

14:23-26.

1974. First record of the chaetognath genus Krohnittella in the Pacific and

.. description of a new species. Wasmann J. BioI. 32:297-301.

BJORNBERG, T. K. S.

1971. Distribution of plankton relative to the general circulation system in

the area of the Caribbean Sea and adjacent regions. In UNESCO-FAO

Symposium on Investigations and Resources of the Caribbean Sea and Adjacent Regions, Curacao, November, 1968, p. 343-356. UNESCO, Paris.

BONE, Q., and A. PULSFORD.

1978. The arrangement of ciliated sensory cells in Spadella (Chaetognatha).

J. Mar. BioI. Assoc. U.K. 58:565-570.

BUMPUS, D. F., and E. L. PIERCE.

1955. The hydrography and the distribution of chaetognaths over the continental shelf off North Carolina. Pap. Mar. BioI. Oceanogr., Deep-Sea Res.

Suppl. to Vol. 3:92-109.

CASANOVA, J.-P.

1977. La faune pelagique profonde (zooplancton et micronekton) de la province Atlanto-Mediterraneenne. These, L'Universite de Provence, AixMarseille, 455 p.

CHENEY, J.

1982. The spatial and temporal abundance patterns of chaetognaths in the

western North Atlantic Ocean. Ph.D. Thesis, Woods Hole Oceanographic

Institution and Massachusetts Institute of Technology, 337 p.

CLAUS, c., and K. GROBBEN.

1905. Lehrbuch der Zoologie. N.G. Elwert'sche Verlagsbuchhandl., Marburg in Hessen.

COLMAN, 1. S.

1959. The "Rosaura" expedition 1937-38. Bull. Br. Mus. (Nat. Hist.) Zool.

5:219-253.

CONANT, F. S.

1895. Description of two new chaetognaths (Spadella schizoptera and Sagilla

hispida). Ann. Mag. Nat. Hist., Ser. 6, lti:288-292.

1896. Notes on the chaetognaths. Ann. Mag. Nat. Hist., Ser. 6, 18:201-214.

DALLOT, S.

1970. L'anatomie du tube digestif dans la phylogenie et la systematique des

chaetognathes. Bull. Mus. Natl. Hist. Nat. Ser. 2,42:549-565.

31

DALLOT, S., and F. DUCRET.

1969. Un chaetognathe mesoplanctonique nouveau: Sagilla mega/ophtha/ma

sp.n. Beaufortia 17:13-20.

DAVID, P. M.

1955. The distribution of Sagilla gazellae Ritter-Zahony. Discovery Rep.

27:235-278.

1956. Sagilla p/anctonis and related forms. Bull. Br. Mus. (Nat. Hist.) Zool.

4:437-451.

1958a. The distribution of Chaetognatha of the Southern Ocean. Discovery

Rep. 29:199-228.

1958b. A new species of Eukrohnia from the Southern Ocean with a note on

fertilization. Proc. Zool. Soc. Lond. 131 :597-606.

DAVIS, C. C.

1949. Observations of plankton taken in marine waters of Florida in 1947

and 1948. Q. J. Fla. Acad. Sci. 12:67-103.

DAWSON, J. K.

1968. Chaetognaths from the Arctic Basin, including the description of a new

species of Heterokrohnia. Bull. South. Calif. Acad. Sci. 67:112-124.

DEEVEY, G. B., and A. L. BROOKS.

1971. The annual cycle in quantity and composition of the zooplankton of the

Sargasso Sea off Bermuda. II. The surface to 2000 m. Limnol. Oceanogr.

16:927-943.

DUCRET, F.

1965. Les especes du genre Eukrohnia dans les eaux equatoriales et tropicales

africaines. Cah. O.R.S.T.O.M. Ser. Oceanogr. 3(2):63-78.

1975. Structure et ultrastructure de l'oeil chez les chaetognathes (genres

Sagitra et Eukrohnia). Cah. BioI. Mar. 16:287-300.

1977. Structure et ultrastructure de l'oeil chez les chaetognathes (genres

Sagilla et Eukrohnia). Incidences biologiques, biogeographiques et phylogenetiques. These, L'Universite de Provence, Aix-Marseille, 119 p.

EAKIN, R. M.

1968. Evolution of photoreceptors. In T. Dobzhansky, M. K. Hecht, and W. C.

Steere (editors), Evolutionary biology, Vol. 2, p. 194-242. AppletonCentury-Crofts, N.Y.

EAKIN, R. M., and J. A. WESTFALL.

1964. Fine structure of the eye of a chaetognath. J. Cell. BioI. 21: 115-132.

EVERY, M. G.

1968. The taxonomy and areal distribution of the Chaetognatha in the

oceanic Gulf of Mexico. M.S. Thesis, Texas A & M University, College

Station, 46 p.

FAGETTI G., E.

1968. New record of Eukrohnia bathyantarctica David, 1958, from the Gulf

of Mexico and Caribbean Sea. Bull. Mar. Sci. 18:383-387.

FAURE, M.-L.

1952. Contribution a l'etude morphologique et biologique de deux chaetognathes des eaux Atlantiques du Maroc: Sagilla jriderici Ritter-Zahony et

Sagitta bipunctata Quoy & Gaimard. Vie Milieu 3:25-43.

FEIGENBAUM, D. L.

1977. Nutritional ecology of the Chaetognatha with particular reference to

external hair patterns, prey detection, and feeding. Ph.D. Thesis, University

of Miami, Florida, 106 p.

1978. Hair-fan patterns in the Chaetognatha. Can. J. Zool. 56:536-546.

FEIGENBAUM, D., and M. R. REEVE.

1977. Prey detection in the Chaetognatha: Response to a vibrating probe and

experimental determination of attack distance in large aquaria. Limnol.

Oceanogr. 22:1052-1058.

FIGUEIRA, A. J. G.

1972. Occurrence of Eukrohnia bathype/agica Aivariiio 1962 (Chaetognatha)

iI. the Atlantic waters of Canada. J. Fish. Res. Board Can. 29:213-214.

FOWLER, G. H.

1905. Biscayan plankton collected during a cruise of H.M.S. Research, 1900.

III. The Chaetognatha. Trans. Linn. Soc. Lond. 2d Ser. (Zool.) 10:55-87.

1906. The Chaetognatha of the Siboga expedition. Siboga Exped. 21: 1-86.

1907. Chaetognatha. National Antarctic Exped., 1901-1904,3 (Zool. and

Bot.) (6):1-6.

FRASER, J. H.

1952. The Chaetognatha and other zooplankton of the Scottish area and their

value as biological indicators of hydrographical conditions. Scottish Home

Dep., Mar. Res. 2: I-52.

FURNESTlN, M.-L., and F. DUCRET.

1965. Eukrohnia proboscidea nouvelle espece de chaetognathe. Rev. Trav.

Inst. peches Marit. 29:271-273.
GERMAIN, L., and L. JOUBIN.

1916. Chetognathes proven ant des campagnes des yachls Hirondelle et

Prineesse-Alice (1885-1910). Resull. Camp. Sci. Monaco 49: 1-118.

GHIRARDELLl, E.

1968. Some aspects of the biology of the chaetognaths. Adv. Mar. BioI.

6:271-375.

GRANT, G. C.

1963a. Chaetognatha from inshore coastal waters off Delaware, and a northward extension of lhe known range of Sagitta lenuis. Chesapeake Sci.

4:38-42.

1963b. Investigations of inner continental shelf waters off lower Chesapeake

Bay. Part IV. Descriptions of the Chaelognatha and a key to their identification. Chesapeake Sci. 4:107-119.

1967. The geographic distribution and taxonomic varialion of Sagil/a serralodenlata Krohn 1853 and Sagitta tasmanica Thomson 1947 in the North

Atlanlic Ocean. Ph.D. Thesis, University of Rhode Island, Kingston, 116 p.

1977. Seasonal distribution and abundance of lhe Chaelognatha in lhe lower

Chesapeake Bay. Estuarine Coastal Mar. Sci. 5:809-824.

HENSLEY, J. L.

1977. A study of the zooplankton composition at a twenty-four hour station

in waters north of Cuba. M.S. Thesis, Old Dominion University, Norfolk,

Va., 98 p.

HYMAN, L. H.

1959. The invertebrates. Vol. V, 783 p. McGraw-Hili, N.Y.

KING, 1. E.

1949. A preliminary reporl on the plankton of the wesl coasl of Florida. Q.

J. Fla. Acad. Sci. 12:109-137.

LAGUARDA-FIGUERAS, A.

1967. Estudio sistematico y distribucion de Sagitta Iriderici en la Laguna de

Terminos, Campeche, Mexico. An. Inst. BioI. Nal. Auton. Mexico 38, Ser.

Cienc. del Mar y Limnol. 1:47 -57.

LEGARE. J. E. H., and E. ZOPPI.

1961. NOlas sobre la abundancia y distribucion de Chaetognalha en las aguas

del oriente de Venezuela. Bol. Inst. Oceanogr. 1:1 -25.

LEWIS. J. B., and A. G. FISH.

1969. Seasonal variation of the zooplankton fauna of surface waters enlering

the Caribbean Sea at Barbados. Caribb. J. Sci. 9:1-24.

MARUMO, R., and M. KITOU.

1966. A new species of Helerokrohnia (Chaetognatha) from lhe western North

Pacific. La Mer 4: I78-183.

MATfLIN, R. H., Jr.

1974. Chaetognaths of the Caribbean Sea. M.S. Thesis, The University of

Wesl Florida, Pensacola, 81 p.

MAWSON. P. M.

1944. Some species of the ehaetognath genus Spadel/a from New South

Wales. Trans. R. Soc. S. Ausl. 68:327-333.

McLELLAND, J. A

1978. The summer distribution of Chaetognalha in the northeasterr Gulf or

Mexico. M.S. Thesis, University of Southern Mississippi, Hattiesburg, 173

p.

1980. Notes on the northern Gulf of Mexico occurrence of Sagitta Iriderici

Ritter-Zahony (Chaetognatha). Gulf Res. Rep. 6:343-348.

MICHAEL, E. L.

1911. Classification and vertical distribution of the Chaetognalha of the San

Diego region. Univ. Calif. Publ. Zool. 8:21-186.

MICHEL. H. B., M. FOYO, and D. A. HAAGENSEN.

1976. Caribbean zooplankton. Office of Naval Research. Department of

the Navy, U.S. Gov. Print. Off., Wash., D.C., 712 p.

MOORE, H. B.

1949. The zooplankton of lhe upper waters of the Bermuda area of the North

Atlantic. Bull. Bingham Oceanogr. Collect., Yale Univ. 12(2):1-97.

MULKANA, M. S., and T. D. MclLWAIN.

1973. The seasonal occurrence and abundance of Chaetognatha in M :ssissippi

Sound. Gulf Res. Rep. 4:264-271.

OWRE, H. B.

1960. Plankton of the Florida Current. Part VI. The Chaetognatha. Bull.

Mar. Sci. Gulf Caribb. 10:255-322.

1963. The genus Spadel/a (Chaetognatha) in the western North Atlantic

Ocean, with descriptions of two new species. Bull. Mar. Sci. Gulf Caribb.

13:378-390.

1972a. Some temperalures, salinities, and depths of colleclion of Eukrohnia

balhyantarctica (Chaetognalha) in the Caribbean Sea. Bull. Mar. Sci.

22:94-99.

1972b. Marine biological investigations in thc Bahamas. 18. The genus

Spadel/a and olher Chaetognatha. Sarsia 49:49-58.

1973. A new chaetognath genus and species, with remarks on lhe taxonomy

and distribution of others. Bull. Mar. Sci. 23:948-963.

32

OWRE, H. B., and F. M. BAYER.

1962. The systemalic position of the middle Cambrian fossil Amiskwia

Walcott. J. Paleonlol. 36: 1361-1363.

OWRE, H. B., and M. FOYO.

1971. Studies on thc zooplankton of the Caribbean Sea. In UNESCO-FAO

Symposium on Investigations and Resources of the Caribbean Sea and Adjacent Regions, Curacao, November 1968, p. 503-508. UNESCO, Paris.

1972. Studies on Caribbean zooplankton. Description of the program and

results of the firsl cruise. Bull. Mar. Sci. 22:483-521.

OWRE, H. B., and J. K. LOW.

1969. Methods of collecting net plankton from a series of known depths

throughout the water column. Bull. Mar. Sci. 19:911-921.

PIERCE, E. L.

1951. The Chaetognatha of the west coast of Florida. BioI. Bull. (Woods

Hole) 100:206-228.

1953. The Chaetognatha over the continental shelf of North Carolina with

attention to their relation to the hydrography of the area. J. Mar. Res.

12:75-92.

1954. Notes on the Chaetognatha of the Gulf of Mexico. U.S. Fish Wildl.

Serv., Fish. Bull. 55:327-329.

1958. The Chaelognatha of lhe inshore waters of North Carolina. Limnol.

Oceanogr. 3:166-170.

1962. Chaetognatha from the Texas Coast. Publ. Insl. Mar. Sci., Univ. Tex.

8:147-152.

PIERCE, E. L., and M. L. W ASS.

1962. Chaetognatha from the Florida Currenl and coaslal water of the southeastern Atlantic slates. Bull. Mar. Sci. Gulf Caribb. 12:403-431.

PIERROT-BULTS, A. C.

1969. The synonymy of Sagil/a planCIOn is and Sagil/a zelesios (Chaetognalha).

Bull. Zool. Mus. Univ. Amst. I: 125-129.

1970. Variability in Sagil/a planctonis Steinhaus, 1896 (Chaetognatha) from

West-African walers in comparison to North Atlantic samples. Atlantide

Rep. 11:141-149.

1975. Taxonomy and zoogeography of Sagil/a planelOnis Steinhaus, 1896

(Chaetognatha) in the Atlanlic Ocean. Beaufortia 23:27-51.

1979. On the synonymy of Sagil/a decipiens Fowler, 1905, and Sagil/a neodeeipiens Tokioka, 1959, and the validity of Sagil/a sibogae Fowler, 1906.

Bull. Zool. MLS. Univ. Amst. 6:137-143.

1982. Vertical distribution of Chaetognatha In the central northwest Atlantic

ncar Bermuda. BioI. Oceanogr. 2:31-61.

PRADO. M. S. de A.

1961. Distribuciio dos Chaetognatha no Atlilntico Sud Occidental. Bol. Insl.

Oceanogr. 11: 15-49.

REEVE, M. R.

1964a. Feeding of zooplankton, with special reference to some experiments

with Sagitta. Nature (Lond). 201:211-213.

1964b. Sludies on the seasonal variation of the zooplankton in a marine subtropical in-shore environment. Bull. Mar. Sci. Gulf Caribb. 14:103-122.

1966. Observations on the biology of a chaetognath. In H. Barnes (editor),

Some contemporary studies in marine science, p. 613-630. Allen & Unwin,

Lond.

1970a. The biology of Chaetognatha. I. Quantitative aspects of growth and

egg production in Sagitta hispida. In J. H. Steele (editor), Marine food chains,

p. 168-189. Oliver & Boyd, Ltd., Edinburgh.

1970b. Complete cycle of development of a pelagic chaetognath in culture.

Nature (Lond.) 227:381.

REEVE, M. R., and T. C. COSPER.

1975. Chaelognatha. In A. C. Giese and 1. S. Pearse (editors), Reproduction

in marine invertebrates, Vol. 2, p. 157-184. Acad. Press, N.Y.

REEVE, M. R., and B. LESTER.

1974. The process of egg-laying in the chaetognath Sagitta hispida. BioI.

Bull. (Woods Hole) 147:247-256.

REEVE, M. R., J. E. G. RAYMONT, and J. K. B. RAYMONT.

1970. Seasonal biochemical composition and energy sources of Sagitta hispida. Mar. BioI. (Berl.) 6:357-364.

REEVE, M. R., and M. A. WALTER.

1972a. Conditions of cullure, food-size selection, and the effects of lemperature and salinity on growth rate and generation time in Sa~;lf{l hispidn

Conant. J. Exp. Mar. BioI. Ecol. 9: 191-200.

1972b. Observations and experiments on methods of fertilization in the

chaetognath Sagitta hispida. BioI. Bull. (Woods Hole) 143:207-214.

RITfER-ZAHONY, R. von.

1909. Die Chaetognathen der Gazelle-Expedition. ZooI. Anz. 34:787 -79~.

1910. Westindische Chatognathen. Zool. Jb., Suppl. 11:133-144.

1911 a. Revision der Chalognathen. Dtsch. SudpolExped. I~: 1-71.

1911b. Chaetognathi. Tierreich 29:1-35.
STEINHAUS, O.

1896. Die Verbreitung der Chatognathen im Sudatlantischen und Indischen

Ozean. Inaug. Diss. Kiel. L. Handorff, Kiel, 49 p.

STEPIEN, J. C.

1978. Biological characlerization of deep flow reversals in the Straits of

Florida. Ph.D. Thesis, University of Miami, Fla., 295 p.

1980. The occurrence of chaetognaths, pteropods and euphausiids in relation

to deep flow reversals in the Straits of Florida. Deep-Sea Res. 27A:987-

1011.

SUAREZ-CAABRO, J. A.

1955. Quetognatos de los mares Cubanos. Mem. Soc. Cubana His!. Na!. 22:

125-180.

1959. Salinidad, temperature y plancton de las aguas costeras de Isla de Pinos.

Monogr. Lab. BioI. Mar. Univ. S. Tomas 7: 1-30.

SUAREZ-CAABRO, J. A., and E. MADRUGA.

1960. The Chaetognatha of the northeastern coast of Honduras, Central

America. Bull. Mar. Sci. Gulf Caribb. 10:421-429.

SUND, P. N.

1959. A key to the Chaetognatha of the tropical eastern Pacific Ocean. Pac.

Sci. 13:269-285.

TCHINDONOVA, V. G.

1955. Chaetognatha of the Kurile-Kamchatka Trench. Tr. Ins!. Okeanol.

Akad. Nauk SSSR 12:298-310.

THOMSON, J. M.

1947. The Chaetognatha of south-eastern Australia. Bull. Counc. Sci. Ind.

Res. Aus!. 222:1-43.

TOKIOKA, T.

1939. Chaetognaths collected chiefly from the bays of Sagami and Suruga,

with some notes on the shape and structure of the seminal vesicle. Rec.

Oceanogr. Works Jpn. 10:123-150.

33

1940. A small collection of chaetognaths from the coast of New South Wales.

Rec. S. Aus!. Mus. 20:367-379.

1942. Systematic studies of the plankton organisms occurring in Iwayama

Bay, Palao. III. Chaetognaths from the bay and adjacent waters. Palao

Trop. BioI. Stn. Stud. 2:527-548.

1955. Notes on some chaetognaths from the Gulf of Mexico. Bull. Mar. Sci.

Gulf Caribb. 5:52-65.

1961. Notes on Sagitta friderici Ritter-Zahony collected off Peru. Postilla,

Yale Peabody Mus. Nat. His!. 55:1-16.

1965a. The taxonomical outline ofChaetognatha. Publ. Seta Mar. BioI. Lab.

12:335-357.

1965b. Supplementary notes on lhe systematics ofChaetognatha. PubI. Seta

Mar. BioI. Lab. 13:231-242.

1974. On the specific validity in species pairs or lrios of plankton animals,

distributed respectively in different but adjoining water masses, as seen in

chaetognaths. Publ. Seta Mar. BioI. Lab. 21 :393-408.

TOKIOKA, T., and D. PATHANSALI.

1963. Another new chaetognath from Malay waters, with a proposal of

grouping some species of Sagitta into subgenera. Publ. Seta Mar. BioI. Lab.

11:119-123.

UROSA, L. J., and T. S. S. RAO.

1974. Distribucion de quetognatos y biomasa del zooplancton en la parte

occidental del Atlantica tropical, durante Julio y Agosto de 1968. Bol. Ins!.

Oceanogr. Univ. Oriente )3:53-66.

VANNUCCI, M., and K. HOSOE.

1952. Resultados cientificos do cruzeiro de "Baepandi" e do "Vega" a IIha

da Trinidade. Chaetognatha. Bol. Ins!. Oceanogr. S. Paulo 3:5-30.

YOSII, N., and T. TOKIOKA.

1939. Notes on Japanese Spadella (Chaetognatha). Anno!. Zool. Jpn. 18:

267-275.