421 

NOAA Technical Report NMFS Circular 421 

Larval Development of 

Shallow Water Barnacles of 

the Carolinas (Cirripedia: 

Thoracica) With Keys 

to Naupliar Stages 

William H. Lang 

February 1979 

U.S. DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric Administration 

National Marine Fisheries Service 
NOAA TECHNICAL REPORTS 

National Marine Fisheries Service, Circulars 

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~) 

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Continued on inSIde bark cover 
NOAA Technical Report NMFS Circular 421 

Larval Development of 

Shallow Water Barnacles of 

the Carolinas (Cirripedia: 

Thoracica) With Keys 

to Naupliar Stages 

William H. Lang 

February 1979 

u.s. DEPARTMENT OF COMMERCE 

Juanita M. Kreps , Secretary 

National Oceanic and Atmospheric Administration 

Richard A. Frank, Administrator 

Terry L. Leitzeli , Assistant Administrator for Fisheries 

National Marine Fisheries Service 
The National Marine Flaberiet Semce ( FS) doeIlIOt approft, 

ommend or endone any proprietary product or proprietarJ ... 

mentioned in thia publication. 0 referenee Ihall be made to PS, or 

to thia publieation furniahed by MFS, in any advvtillna' or ,.... 

motion whieh would indicate or imply that FS appro~, ftCO'D .. dI 

or endonea any proprietary produet or proprietary material ..... tIGaIcI 

herein. or which haa aa ita purpOIe an intent to cauae directly or 1DdIreetI, 

the advert!eed produet to be uaed or purc:baaed beea ... of thJa 

publication. 
CONTENTS 

Page 

Introduction . . . . . . . . . 

Materials and methods 

Larval development of barnacles 

Definition and diagnostic characters 

Larval descriptions . . . . . 

Balanus venustus Darwin . . . 

Balanus eburneus Gould 

1 

1 

3 

3 

7 

7 

9 

Balanus amphitrite amphitrite Darwin 

Balanus improvisus Darwin 

Balanus subalbidus Henry 

Balanus trigonus Darwin 

Conopea galeata (Linnaeus) 

Chelonibia patula (Ranzani) 

Chthamalus tragi lis Darwin 

Octolasmis muelleri (Coker) 

Lepas spp . ....... . 

Nauplius SC . . . . . . . 

Keys to the barnacle larvae of the Carolinas 

Assigning stages ...... . 

Species identification of nauplii 

Cyprids 

Discussion . . . 

Acknowledgments 

Literature cited 

13 

14 

17 

18 

19 

19 

22 

24 

25 

27 

29 

29 

31 

36 

36 

37 

38 

Figures 

1. Descriptive terminology of barnacle larvae . . . . . . . . . . . . . . . . 4 

2. Setation formulae for the mandible of stage IV Balanus eburneus nauplius 5 

3. Examples of barnacle larvae setal types .............. 6 

4. Diagnostic morphological features of balanomorph nauplii at each stage 8 

5. Balanus venustus. Shield outlines ...... .. 9 

6. Balanus venustus. Naupliar antennule and mandible 10 

7. Balanus venustus. N aupliar antenna . . . . . . . 11 

8. Balanus venustus. Abdominal process and labrum . 12 

9. Balanus eburneus. Shield outlines and abdominal process 13 

10. Balanus amphitrite amphitrite. Shield outlines, cyprid carapace profile, and abdominal process ......................... .... .. 14 

11. Balanus improvisus. Shield outlines ................. 15 

12. Balanus improvisus Antenna, antennule, labrum, and abdominal process 16 

13. Balanus subalbidus. Shield outlines, labrum, and abdominal process 17 

14. Balanus trigonus. Shield outlines ....... 18 

15. Balanus trigonus. Antenna and mandible . . . . . . . . . . . . . 19 

16. Balanus trigonus. Abdominal process and labrum . . . . . . . . . 20 

17. Conopea galeata. Shield outlines, labrum, dorsal shield spines, and abdominal process 21 

18. Chelonibia patula. Egg, shield outlines, and carapace profile 21 

19. Chelonibia patula. Antennules 22 

20. CJ:!-elonibia patula. Antennae ......... 23 

21. Chelonibia patula. Mandibles ......... 24 

22. Chelonibia patula. Abdominal process and labrum 25 

23. Chthamalus tragilis. Shield outlines, lateral profile, and carapace outline 26 

24. Chthamalus tragilis. Antennule, antenna, and mandible 26 

25. Chthamalus tragi lis. Abdominal process and lateral profile 27 

26. Chthamalus tragilis. Labrum 27 

27. Octolasmis muelleri. Shield outlines 28 

III 
28. Octolasmis forrestii. Shield outlines . .. ... .... . . ...... ... .... 28 

29. Octolasmis forrestii. Antennule, antenna, mandible, and labrum ............ 29 

30. Lepas pectinata. Shield outlines and lateral profiles, abdominal spines, labrum, antennule, antenna, and mandible .............. 30 

31. "Nauplius SC." Shield outlines and lateral profiles . ......... . ... 31 

32. "Nauplius SC." Antennule, antenna, and mandible . . . . . . . . . . . . . . 32 

33. Stage IT nauplii of Balanu.-; amphitrite-complex species common in Carolina waters 32 

34. Stage IT nauplii of barnacle species found in Carolina waters 33 

35. Morphological features of Carolina barnacle nauplii 35 

36. Cyprids of South Carolina . . . . . . . . . . . . 36 

Tables 

1. Thoracican Cirripedia of the South Carolina coast 

2. Studies on barnacle larval development 

3 Setal types of cirriped nauplii . . . . . . . . 

4. Typical setation counts for balanid nauplii 

5. Setation formulae for nauplii of Balanus venustus 

6. Setation formulae for nauplii of Balanus eburneus 

7. bize of Balanus eburneus and Balanus amphitrite larvae 

8. Setation formulae for nauplii of Balanus a. amphitrite 

9. Setation formulae for nauplii of Balanus trigonus 

10. Setation formulae for nauplii of Chelonibia patula . 

11. Setation formulae for nauplii of Chthamalus fragilis 

12. Structure of the Octolasmis lowei-complex 

13. Setation formulae for nauplii of Octolasmis muelleri 

14. Setation formulae for nauplii Y ........ . 

15. Size ranges of barnacle nauplii obtained by laboratory rearing and plankton samples 

16. Size of barnacle cyprids reared in the laboratory .......... . 

17. Setal counts for the antennae of stage VI nauplii of some barnacle species 

IV 

1 

2 

5 

8 

9 

13 

15 

15 

18 

22 

26 

27 

29 

31 

34 

34 

37 
Larval Development of Shallow Water Barnacles of 

the Carolinas (Cirripedia: Thoracica) With 

Keys to Naupliar Stages! 

WILLIAM H. LANG 2 

ABSTRACT 

The report includes an introduction to structure, descriptions, and illustrated keys to the barnacle 

larvae of Georgetown, S.C. Descriptions of 13 species are based on both laboratory reared and field 

specimens. The complete naupliar development of Chelonibia patula, Chthamalus tragilis, Balanus 

venustus, Balanus subalbidus, Octolasmis torrestii, and an unknown species, " nauplius SC, " is 

described for the first time. 

INTRODUCTION 

The abundance and ability of barnacles to settle on 

virtually any solid substrate has made them a target of 

numerous detailed studies (see Newman and Ross 1976). 

Although the biology of many adult barnacles is relatively well studied, little information exists on the larval 

biology of cirripeds. This is particularly true of temperate and tropical species, as is evident by the limited information available for cirriped larvae along the southeastern coasts of the United States. Of over 25 species of 

thoracican cirripeds known to occur in South Carolina 

waters (Table 1), life histories are known for five species 

(Table 2) and the larvae of only two species, Balanus amphitrite amphitrite and Balanus ebumeus, have been 

studied regionally (Costlow and Bookhout 1957, 1958). 

This study was initiated to provide missing larval 

descriptions of common southeastern barnacle species 

and to construct a key for field identification of barnacle 

nauplii of coastal Carolina waters. In addition, some 

changes in descriptive terms and setation formulae are 

proposed. 

MATERIALS AND METHODS 

Adult barnacles were primarily collected in North Inlet and Winyah Bay near Georgetown, S.C. Of 11 species 

obtained in the Georgetown region (Table 1), larvae were 

reared for 10 species. Additional material for comparative purposes was collected at Pettaquamscutt Pond and 

Narragansett Bay, R.I., or obtained from Belize, Central 

America. further details of collection sites and habitats 

are described in the introduction to the larval descriptions. 

'Contribution No. 188 of the Belle W. Baruch Library in Marine Science, University of South Carolina, Columbia, SC 29208. 

'U.S. Environmental Protection Agency, Environmental Research 

Laboratory, Narragansett, RI 02882. 

1 

Various methods and diets were used to rear barnacle 

larvae both to obtain material for descriptions and for 

diet-temperature studies (Lang3) . In general, most descriptive material was obtained using rearing methods 

similar to those of Freiberger and Cologer (1966); however, antibiotics were not used and mixed algal diets 

were employed. Larvae were obtained from adult barnacles maintained in laboratory tanks and fed Artemia 

'Lang, W. H. 1977. The barnacle larvae of North Inlet, South Carolina (Cirripedia: Thoracica). Unpubl. Ph.D. Thesis, Marine Science 

Program, Univ. South Carolina, Columbia, 179 p. 

Table l.- Thoracican Cirripedia of the South Carolina 

coast. (From Zullo and Lang 1978.) 

Suborder Lepadomorpha 

Lepadidae 

Lepas anatifera 

L. anserifera 

L. hilli 

L. pecLinata 

Concho derma auritum 

C. uirgatum 

Scalpellidae 

S calpellum gibbum 

Poecilasmatidae 

Octolasmis hoeki 

Octolasmis muelleri 

Trilasmis spp. 

1(? ) = probable occurrence. 

Suborder Balanomorpha 

Archeobalanidae 

Acasta cyathus (?) 1 

Conopea galeata 

C. merrilli 

Glanaidae 

Balanus a. amphitrite 

B. calidus 

B. eburneus 

B. improuisus 

B. reticulatus (?) 1 

B. subalbidus 

B. trigonus 

B. uenustus 

Chthamalidae 

Chthamalus tragi lis 

Coronulidae 

Chelonibia patula 

C. testudinaria 

Platylepas hexasty los 

S tomatolepas elegans 
Table 2.- Studies on barnacle larval df'velopment. SOUT('~ of larva!': laboraloT} rl'art'd (r), plank!;)n ampl - (p). or both (plr). 

Species Source StageR Location und /Il1thor 

Lepadomorpha 

Scalpellum scalpellum all 'weden (Kaufmann 1965) 

Pollicipes spinosus all ew Zealand (Halham lfj4Sa) 

P mitella all .Japan (YaAugi 1937) 

P. polymerus all r~A. weRt coa t (Lewl 11176) 

Ibla idiotica all ew Zealand (1301 hum 1946b) 

I quadriL'aiL'is all Aust rolla (AndenlOn 1 ) 

I. cumlngl all India (Karande W74 ) 

Lepas fa.mculans p all Pacific (Willemoe '. uhm 

1876; B81nbndRe and 

H. ... tlkelll%6) 

Ver comorpha 

Verruca stroemla p/r 1·\'1 United Kingdom (B8.Slundal 

19 61 

pir I. VI France (Le&sIC 1 

Balanomorpha 

(Chthamaloidea) 

Chlhamalu stellatus p r 1. \'1 L'mted Kmgdom Ba mdale 

1"161 

all IndIA (Dun leI 1 

I·UI Brazi (Lalombe 19731 

C dentatu, p 1 II ulh Afn 'II ( andl n 1 

C mala) en.s1S all indIa (Karande and Thoma 

1976) 

Chamaesipho columna all .. e" Zealand (Barker 1 76) 

C. brunnea all j 'e" ZOo land (Barker 1 76) 

Euraphra ac,tuaru p 1.\ I \\ e t AfrIca ( and on 1 ,) 

Euraphra depre 'sa 1·\1 France LeRale 1 1 

Gctomen. angulosa pir 1·\ I uth Afn a ( andl n 19541 

(Coronulaidea) 

Chelolllbia patula lUI BraZil (Lacombe 1973) 

C testud,nana p I·II India (PhIal 1 ) 

Tetracltta squamosa all Japan (Hirano 1~53) 

T. serrato p I·ll - ut h Afnca k andl n 1 54) 

Tetraclllella karandcl all indIa CKarande 1974b 

(Balanoidea) 

Acasta spongites all United Kmgdom 1.\loy e 1 

Chirona hamer! p/r all l'mted Kmgdom (e n,p 19 2b 

Conopea galeata all C A. west coa, t (:-Iolenoc 

and G<Jmez 197:! 

Eliminius modestus p all United Kingdom (Kmght Jon 

and Waugh 1949) 

Epopella plicatus r all :-;ew Zealand (Barker 1976) 

Semibalanus balanOIdes plr 1·\1 Cnited Kingdom (Bassmdale 

1936) 

p all North Atlantic (Crisp 1962a) 

ail' New York (Freiberger and 

Cologer 1966) 

'Primarily methodology/rearing papers with limited descriptions. 

(day old nauplii through adults), rotifers, and mixed 

algal cultures. Nauplii released from these populations 

were concentrated using a narrow light beam and removed with a pipette to 1 ~m filtered natural seawater 

between 25 and 32% •. A double algal diet of Tetraselmis 

suecia (TET) in combination with Monochrysis lutheri 

(MON), Isochrysis galbana (ISO), Thalassiosira pseu· 

donana (3H), or Skeletonema costatum (SKEL) was 

used as food. Further details of rearing techniques and 

diet results were described in Lang (1976, see footnote 3). 

2 

alldabalanu Ilf per/us p/r I.VI 

Bo CIa angllCum all 

lIolanus bala,1UA plr II 

p all 

}jalanu, cr notus all 

p r all 

H nublllU pr 1.\'1 

IJ amphitrite amphltrlt all 

p I 11 

11 

p II 

II 

II 

11 

8 a a Ie tatu 1 \ I 

8 bUrri, all 

all 

B Impr I p 1·\1 

all 

B Larl a/us al 

all 

B pallid lut bur. p 1 \1 

Bin nu all 

p 1·\1 

all 

all 

B p rfc,ratu II all 

p all 

Megaba/anu 01 Icola p r all 

.\I t tl1ltl1lnabulum I-III 

a\l 

Drawrngs of larvae were made with a camera lucid 

When possible, freshly sacrificed larvae were used for ' 

itial figures. The figures were verified using addition 

material preserved in 70 C:C ethanol or, more commonl 

Formalin and seawater. Measurements were made wi 

an ocular micrometer on unflattened preserved larvaE 

Total length was measured from the anterior edge of th 

cephalic shield to the tip of the dorsal thoracic spinE 

Shield length was measured along the middorsal liD

from anterior to posterior shield borders, exclusive 
lateral or posterior shield spines. Width was mea ured at 

the widest portion of the shield exclusive of frontolateral 

horns and shield spines. Cyprid length was measured 

from the anterior to posterior carapace margin. Cyprid 

"width" or depth was measured as the greatest distance 

from the dorsal to ventral carapace margins. 

LARVAL DEVELOPMENT OF BARNACLES 

The most common sequence of larval development for 

thoracican cirri peds consists of six naupliar and one cyprid stage. Using plankton reconstructions, WillemoesSuhm (1876) and Groom (1894-95) reported six naupliar 

and one cyprid stage for both the lepadomorph Lepas 

fascicularius and the balanomorph Balanus perforatus. 

Herz (1933) reported eight naupliar stages from cultures 

of Balanus crenatus larvae however, Bassindale (1936), 

using both cultures and plankton material, found a 

consistent pattern of six naupliar stages and one cyprid 

stage for Verruca stroemia, Semibalanus balanoides, and 

Chthamalus stellatus. Most studies since then have confirmed this pattern of larval development (Table 2). A 

second study of B. crenatus yielded six naupliar stages 

(Pyefinch 1948). Conclusive proof of the number oflarval 

stages was provided by the studies of Costlow and Bookhout (1957, 1958). Counts of molts of the larvae of 

Balanus eburneus and B. amphitrite amphitrite reared 

individually in small compartments consistently yielded 

the expected pattern of six naupliar and one cyprid 

stages. 

A remarkably uniform pattern of cirriped larval 

aevelopment is evident. Adults release newly hatched 

nauplii which, within a short time span, molt to stage II 

nauplii. Further development (usually dependent on 

roper diet) produces four additional naupliar stages and 

the cyprid. The nonfeeding ::;yprid will select a substrate, settle, and undergo final metamorphosis to a 

·uvenile. 

Exceptions to this pattern of five planktotrophic 

aupliar stages are known. Nilsson-Cantell (1921) re-

'ewed rather sparse observations on deepwater cirripeds in which the naupliar stage is passed through in the 

egg. Fully developed cyprid larvae or advanced 

etanauplii are released at hatching. Barnard (1924) 

ound that over half (12 of 17) of South African Scalellum species lack free-swimming naupliar stages; this 

characteristic appears to be independent of adult depth 

tlistributions. Complete naupliar development without 

eeding (lecithotrophic development) is also known, 

ither with an irregular molt in nauplii and precociou 

cyprid development (Anderson 1965) or with six naupliar 

tages and cyprid (Kaufmann 1965). 

DEFINITION AND DIAGNOSTIC 

CHARACTERS 

As de cribed by Groom (1 94). the ba ic anatomy of 

the cirriped naupliu i well estabh hed (Kruger 1940: 

~Vallev 1969). \\'alle\ (1969) extended Gro m's ob_enaion 'on the intern~l anatomy of the nauphus t:Mi3 

balanu.~ balanoide ), but noUlbl ddltion t th 

nal morphology of lan:ae will probabl: r t n nmng 

electron micro copy (E~l) tudie, uch a th 

Iy reported by Walker (1 73, 197 a) and Ham 

\Valker (1976). 

As a guideline to de. cription!; pr ent d in lhl tud. 

a urn mary of external morphology and ta onoml 

character of cirriped lan'ae follow.. !thou h m m t 

case thi repre,'ent a. imple review of pH t lit 'Tatun, 

orne ba ic change lD terminology of lar .... al tru tur 

and setal type are propo ed. 

The dor al surface of the naupliu. (Fig. lAo H I omposed almo t entirely of a unitary carapIICl' hield 

(Ander on 1973) or correctly, the cephalic hield ). 

WIth a pair of prominent frontolateral horn (fh) n 

teriorly and a dorsal thoracic pine (DT ) po t riorl) 

Ventrally, there are three paIr of jointed aPi> mia 

the antennules (AnI), the antennae (An2), and the 

mandibles (Mn). A paIr of unjomted filiform app ndages-the frontal filament -extend anteriorl) bet .... etn 

the antennules. A prominent labrum (lb) Ii b t\\ en 

the antennae and overhang the mouth. 'I he poteroventral "po tnaupliar region" (Ander on 19i3) lun· 

sists of the abdominal proce (AP) which terminate 

with the furcal spmes. The ventral urface betw en th 

mouth and postnaupliar region has a com pie Ilrm) of 

small processes referred to as the etose regIOn It lll· 

cludes the maxillary portIOn of the cephalon and the In· 

cipient thorax. 

Cephahc shIeld. Despite the virtually univer:<al relerence to the nauphar carapace in the hteratur , th 

naup 1iu , by definition, lack a true carapac nde on 

1973; Moore and McCormick 19 9: • 'ewman per~. ommun.). In naupliar stage I-III the ,hleld taper dlredl 

into the DTS. At tage IV, a distmct po terior hleld (p ) 

border is formed ( ee FIg. 5); this border u. uell) ha tw 

ps spines (see Fig. 4 IV-VI). The shield may 1 0 ho\ 

dorsal and/or lateral pine or lack ,pme~ enUr 1 

Frontolateral horns. The,e distll1cti\e tructure ar 

pe ie". 

called th "c ud I 
DTS 

A DTS 

D 

Figure 1.-Descriptive terminology of barnacle larvae: ventral view (A) and lateral view (B) of Conopea galeata stage II nauplius; Chelonibia 

patula cyprid (C) and detail of the antennule (D). abs, abdominal spines; AnI, antennule; An2, antenna; AP, abdominal process; ao, adhesive organ (on the third segment of AnI); ce, compound eye; cf, caudal furca ; cs, cephalic shield; ds, dorsal shield spine; DTS, dorsal thoracic 

spine; en, endopodite; ex, exopodite, fr, frontal filament; tn, frontolateral horn ; fs, furcal spines; gn, gnathobase; lb, labrum; Is, lateral shield 

spines; me, median or naupliar eye; Mn, mandible; mr, maxillary region; oc, oil cells; pa, pigmented area ; sr, setose region; ta, thoracic appendage; tr, thoracic region. All scales = 0.1 mm. 

chthamalid larvae. Its relative length compared with 

shield and AP may provide diagnostic characteristics. 

Frontal filaments. Recently studied by Kauri (1962, 

1966), and Walker (1974a), their function remains debated. Often closely folded to the body wall in stage I 

nauplii, with the exception of some chthamalid species, 

the filaments are evident in all subsequent naupliar 

stages. 

Jointed appendages. The AnI is uniramous and consists of four segments in late naupliar stages. The An2 is 

4 

biramous, the endopod and exopod arising from a twosegmented base. By stage VI the exopod (= exopodite) 

consists of nine segments and the endopod (= endopodite) is three-segmented. Similar to the antenna, the Mn 

is biramous with a two-segmented base, two-segmented 

endopod, and five-segmented exopod. 

Labrum. The lb is relatively large and rigidly fixed to 

the body above the mouth. The shape of the free end appears to be a useful family characteristic. 

Maxillary and thoracic regions. The setose region, posterior to the true mouth and extending to the abdominal 
spines, is divided in two: the anterior maxillary and 

posterior thoracic regions. Rudimentary maxillae and 

anlage of the thoracic appendages will be evident in later 

naupliar stages. Functional appendages first appear in 

the cyprid. 

Abdominal process. The AP arises from the ventroposterior body region and terminates in a stem bearing 

spines of the caudal furca. Pairs of lateral abdominal 

spines appear at stage II and increase in number with 

subsequent molts. Norris and Crisp (1953) defined three 

sets of serially homologous spines which develop in a 

highly predictable order in balanid larvae (Fig. 4). 

Setation. Setae are well developed on the limbs and 

ventral body regions, serving both a natatory and feeding 

function (Gauld 1959). The number and types of setae 

are fundamental morphological characters which are, in 

part, used for determining the naupliar stage (Fig. 4, 

Table 4) and, to a lesser extent, the species. 

Bassindale (1936) initiated use of a setation formula 

similar to that used for cope pod appendages. The formula specifies only setal numbers and location. Jones and 

Crisp (1954) devised a graphical method to show setal 

numbers, types, and relative lengths. Newman (1965) 

combined the simplicity of Bassindale's formula with the 

informational content of the Jones and Crisp graphics to 

create an alphabetical notation. Sandison (1967) further 

modified Newman's system, adding additional setal 

types and using numerical groupings of similar setae. For 

a comparison of these setation formulae, see Figure 2. 

The basic setation formula of Newman (1965) is used 

in this study with some modifications. The initial fOUI 

setal types of cirriped larvae defined by Jones and Crisp 

(1954) and Newman (1965) were expanded to seven types 

by Sandison (1967) (Table 3). A similar but independent trend to define specific setal types in decapod 

larvae was initiated by Bookhout and Costlow (1974), 

their setal types based on the definitions of crayfish setae 

by Thomas (1970). Essentially two problems now exist: 

1) additional setal types undefined by Sandison (1967) 

have been observed in the present study, and 2) there are 

two sets of terms used for respective cirriped and 

decapod setal types. This latter situation does not seem 

warranted based on comparative observations on decapod larvae (Lang and Young 1977; Johns and Lang 1977). 

A) 

BI 0 .14-04.34 3 a 

CI I I111 .•.• I! I I I ~I I I C 

I P PPPP SSSS PSP ,PCP PCP 

E I P 4 P - 4 S ' P S p . S P't; P PCP C 

f'1 p ; 4 P - 45 : PSP,SDCP PCP, G 

Figure 2.-Setation formulae for the mandihl .. \ \ of I " 1\ /Jal 

anu.. cburneu. nauplius; HI formula of B I .. nclal, (I' GI I \ for 

mula of .Jom's and Crisp (19~ll: Ol formulll of :-';l·"m In (I ~) I) 

formula of Sandbon (1967); f) formula u'l'fl hrr, , 81 0 I.bl 

Scalp n.1 mm. 

Bookhout and ostlow (1974) organized the 

terminology and description. of Thoma 197) mt \ 

en basic group for describing th larva of Portunu 

IJpzn carpus. Four of these group apl' fir to ppJ l quail 

to cirriped larvae : 

1. 'imple setae are acuminate with no tul or pr 

Jections. 

2. Plumo e setae poes~ fine hairlik etul c mm 

off oppo it ~ide. of the haft. 

3. PlumodentJ ulate. eta bear halrl! tul on th 

baal part of the. haft and fine or tout dent! ul 

on the di.tal portion. 

4. u. pidate . etae ha\e nlarg d ba nd t u 

shaft. tapenng to a pOint. h( m b furth r 

Table 3.-Setal ~~ pe!> of cirript'd nauplii. 

----- ----- Jone and Crisp (1954) 

Symbol·Type 

: WIthout setules 

I ,,;th setules 

f comb-like 

G • !mathoba"e 

t simple or plumo'(' 

. ewman (l -J 

)mbol.Type 

. ~imple 

p . plumo, 

• combed 
A 

Q 

Figure a.-Examples of barnacle larvae setal types: A) simple; B-E) plumose; F) feathered; G) plumodenticulate; H-K) cuspidate; L) hispid; M) bristled; N, P) gnathobases. Scale = 0.1 mm. 

specified as denticulate, cuspidate, or plumodenticulate cuspidate types. 

Incorporation of these groups, setal types described by 

Sandison (1967), and present observations, result in the 

following setal types used in this paper: 

Simple (S): setae with no setules or projections (Fig. 

3A). 

Plumose (P): setae with fine hairlike setules, short or 

long, usually but not always coming off opposite 

sides of the shaft (Fig. 3B, C, D, E). 

Feathered (F): plumose setae with dense "downy" 

setules and flattened spatulate shaft (Fig. 3F). 

Plumodenticulate (D): plumose setae with denticulate or serrate tip (Fig. 3G). 

Cuspidate (C): setae with enlarged base and stout 

shaft tapering to a point. The presence of stout to 

fine denticules, often comblike in orientation, is 

typical (Fig. 3H, I, J, K). 

Hispid (H): cuspidate setae with flattened modified 

shaft (Fig. 3L). 

6 

Bristled (B): plumose setae .,vith basal portions of 

shaft serrate or "bristled" (Fig. 3M). 

The gnathobase (G) is classically defined as a rigid 

toothed or "biting" process and is located on the basal 

segment of both An2 and Mn in cirriped larvae. Rainbow and Walker (1976) also refer to the An2 endopod 

cuspidate seta (Fig. 3K) as a G. It should be noted that 

the An2 G is a unique structure (Fig. 3 ) while the Mn G 

(Fig. 3P) differs little from other cuspidate setae. By 

convention, any rigid process on the basal segment of the 

appendages will be considered a G; setae at other locations will be classified as one of the above listed types. 

Semantics and definitions of setal types have been 

somewhat altered from those listed by Sandison, but 

only one symbol has been changed (pc=D), thus 

eliminating the superscript and repeated use of P. Feathered setae described by Sandison (Fig. 3E) for 

chthamalid larvae, often closely resemble postaxial plumose setae (An2, endopod) of some balanid larvae, but 

feathered setae have a distinct "spatulate shaft"; and 

enlarged flattened basal region is obvious. Similarly, the 
"bristled" proximal shafts of some AnI setae of Octo" 

lasmis and Lepas larvae are quite distinctive; a new setal 

type (bristled) has been introduced. 

Superscripts will be used to designate setal type variability. Thus, p s infers plumose seta, sometimes simple; 

SP, simple seta, sometimes plumose; po, plumose seta, 

sometimes plumodenticulate; etc. 

The cyprid larva (Fig. lC) is enclosed by a bivalved 

carapace. The carapace may appear textured or sculptured in some species, but is relatively smooth in all 

Carolina species examined. Using scanning EM, numerous small sensory setae and the fh pores are evident 

on the carapace surface (Walker and Lee 1976). 

The naupliar An2 and Mn are transient structures in 

he cyprid and are reduced to rudimentary groups of cells 

during the metamorphosis from nauplius to cyprid (Walley 1969). The AnI, however, is retained as the primary 

ensory and attachment structure. Antennule setation is 

eatly reduced and a prominent attachment organ is 

present (Fig. ID). Nott and Foster (1969) studied the 

~1 of Semibalanus balanoides cyprids in detail and 

concluded that attachment probably occurs by an adhesive disc . At the level of light microscopy, the AnI shows 

little variation between different species. 

Propulsion is provided by six pairs of biramous thoracic swimming appendages. Their embryonic developent is clearly evident in the basal region of the AP in 

stage VI nauplii. The articulate rami of the furca has 

complex sensory processes and perhaps aids in contour 

assessment (Walker and Lee 1976). 

The internal anatomy of the cyprid has been reviewed 

nd studied by Walley (1969). Structures readily evi-

(lent in examination of whole specimens include: the 

naupliar eyespot, paired compound eyes, various pigmented areas, and oil cells. 

LARVAL DESCRIPTIONS 

All cirriped species studied at North Inlet exhibit the 

ypical larval development of six planktotrophic 

aupliar and cyprid stages. The newly hatched stage I 

nauplius is nonfeeding and capable of only weak swiming activity. This stage rapidly molts to planktotrophic 

stage II; it is rarely encountered in plankton tows. The 

remaining five naupliar stages and cypris comprise the 

normal planktonic component of the cirriped life cycle 

and will be the main concern of the following descripions and key. 

With each molt the nauplius increases in size and comlexity. All known planktotrophic balanomorph nauplii 

exhibit basic morphological changes at each molt which 

Hows the accurate staging of any species. A diagramatic outline of key morphological features is presented 

Figure 4; these features will be considered the "noral" developmental sequence. Of North Inlet species, 

nly Octolasmis larvae differs significantly from this patern (Lang 1976). 

Setation of the naupliar appendages is also quite uniorm among most balanid species. Based on a review of 

' xisting descriptions (Table 2), the "normal" or ex7 

pected setal counts are indicated in Table 4. Setal counts 

between different species vary little in most instances; 

variations in setal types occur more often. Although 

detailed studies of setae serve little practical use in routine staging or identification of larvae, details of setation may provide useful information for studies concerning taxonomy, regional variations, feeding mechanisms, 

etc., and should not be ignored in initial larval descriptions. 

Balanus venustus Darwin 

Darwin's (1854) variety B. amphitrite amphitrite was 

raised to specific rank by Harding (1962). Henry and 

McLaughlin (1975) considered Darwin's varieties B. a. 

niueus, B. a. modestus, and B. a. obscurus as synonymous with B. uenustus. Although confusion exists in the 

early literature (see Zullo 1966), B. uenustus is a predominant shallow-water subtidal species from New England to Florida. 

All specimens collected in North Inlet (Georgetown, 

S.C.) were found in subtidal habitats. Balanus uenustus 

was the predominant species on all subtidal debris: 

wood, metal, plastic, glass, shells (but not oyster beds). 

It was abundant on hermit crab shells and occasionally 

on the carapace of horseshoe crabs; spider crabs, Libinia 

emarginata; and blue crabs. 

Although B. uenustus is a common species, no descriptions of its larvae seem to exist. Numerous hatches 

of larvae were successfully reared; adults used to obtain 

larvae for the following descriptions were positively identified by Dora Henry. 

Stage 1. (Fig. 5A). Typical stage I nauplius with rudimentary AP and DTS; fh folded rearward, but rarely collapsed completely against body. 

Stage II. (Fig. 5B). Frontolateral horns extended nearly perpendicular to median body axis; anterior shield 

(as) margin slightly convex to flat; DTS and AP well 

developed, distinctly barbed. Spination quite distinct; 

anterior margin of shield with four small lateral spines, 

side margins with four pairs of similar spines, and one 

larger spine pair at future location of ps margin; one 

short median dorsal spine also present. Entire shield 

margin spinulose (numerous minute spines present). 

Stage III. (Fig. 5C). Frontolateral horns directed 

slightly forward; as margin slightly arched with two 

small lateral spines, spinulose margins, and closely 

spaced pair of median dorsal spines. Maxillules represented by one stout simple seta (see Fig. 8B). 

Stage IV. (Fig. 5D). Shield marginal spination further 

reduced to a variable number of small lateral spines and 

spinulation; paired dorsal spines similar to stage III. Posterior shield margin present; ps spines straight, relatively stout. The DTS is long, generously barbed; AP 

with series two spine pair and single well-developed median spine (see Fig. 8C). 

Stage V. (Fig. 5E). Very similar to stage IV. Shield 

margin spinulose, no larger lateral spines present; paired 

dorsal spines widely spaced and minute. Sene three 
one prea x ial 

eta 

plain tip 

• • 

VI 

: / 

• 

compound eye 

6pr. erles 

two spines 

three preaxial 

elae 

split tiP 

1 P[ each series 

Iwo & Ihree spines 

I wo preiJJual 

'etae 

Figure .t.-Diagnostic morphological features of bilianomorph nouphi t (' h ,tlllCI!. \Momlnal 

Ilnd (ri p (I -3) nd Mo~, ... (1 I). 

I n lion' arl." dallted from :'I,'OrTl 

Table I.-Tpical etation count for balanld nauplu. 

lage Antennule .-\ntenna ~18ndlble 

I OA 2.1.1 o 1.4·0.3 ~ 2 ~.G O13~3222G 

II 04.2.1.1 02.5·0 3.2 ~ 3.C 01 4·01.23 .?G 

ill 1 4.2 I 1 02.5·03224 G 01 4·0.3.3.3 3.G 

IV 1 1 4.2.1.1 0.3.6·0.5.32.4.G 0.1.4·0.4 .3.43.G 

V 1.1 14.2.1.1 1 ( ). 0.5 3.24.G o 1.5·044 43.G 

VI 1.1 14.2.12.1 ( ).0.53.2.4.lJ 01.5-04.44 3.G 

'Variable configuration with a total of 10 or 11 setae. 

·Varlable configuratIOn with a tota: of 11 or 12 .etae. 

spine pair present on AP; series two pair and median 

spine as in stage IV (see Fig. 8E, F). 

Stage VI. (Fig. 5F). Spinulation of shield margin often 

indistinct; most evident on anterior and posterior margins. The ps spines reduced in length but stout; DTS 

long and well armed. 

Cyprid. Virtually identical to B. improvisus (Jones 

and Crisp 1954). No apparent distinctive characteristics. 

8 

Characteri tic morphological feature a ociated with 

each balanid naupliar tage (Fig. 4) are clo'ely followed 

in the larval development of B. uenustu . Lateral hield 

pination is omewhat variable; in orne hatche the 

lateral shield pines are les di tinct and generally mal· 

ler. 

Setation of the naupliar stages (Table 5) closely follows the normal balanid pattern (Table 4). The first 

preaxial seta of AnI is plumo e at stage ill (Fig. 6C), as 
• 

A 

G 

E 

Figure 5.-Balanus venustus. Shield outlines of stages I-VI (A-F) and cyprid carapace profile (G). Scales 

= 0.1 mm. 

Table 5.-Setation formulae for nauplii of BalanWi venWltWi. 

Stage Ani An2 Mn 

VI 

V 

IV 

ill 

IT 

I 

S PPPSPP SPPPS S 

S P P PSPP SP S P S 

S PPSPPSP P S 

PPSPPSP P S 

SSPS SP P S 

SSSS SS S S 

3P8P 

3P6PS 

2P6PS 

2P5P 

SP4PS 

S4S 

PPSPP PSP PD PCP G P 5P 

PPSPP PSP PD PCP G P 4PS 

PPSPS PSP PD PCP G P 4P 

PP P P S PD PCS G P 3PS 

PP S P S PD PC G P 3PS 

SS S S S SS SS G S 3S 

4S DSPS D SCP PCP G 

is DSPS D SCP PCP G 

4S D SS POSCP PCP G 

3S P SS po CP PCP G 

3SP spes PC G 

3S S S S SSG 

I pposed to a simple seta in many species. The first postaxial setal group of the Mn endopod has one to two pluodenticulate setae beginning with stage III (Fig. 61, J). 

The An2 exopodal setae are relatively stout; the endopod is well developed, with one less seta than expected 

(stages III-VI) in the last postaxial setal group adjacent 

to the G (Fig. 7). 

The DTS remains notably long in late stage nauplii 

and is distinctly barbed in all stages (II-VI). The AP is 

also well developed but remains shorter than the DTS; 

abdominal spines are stout and easily observed (Fig. 8AG). Maxillule setation first appears at stage III and increases to six (5 long, 1 short) stout simple setae by stage 

VI. 

The lb is trilobed, the median lobe even with or slight9 

ly extending beyond the lateral lobe (Fig. 8H-JI. Fine 

teeth or denticulations may be pre ent along the lateral 

lobe margins. Three teeth are often present on the margin of the median lobe. 

Larvae increase in size at each molt; lZe vanabllit) increases in later tage (Table 15). nder .lmtlar reanng 

conditions the mean size of B. L'enwstw. nauplii i dltinctly larger than B. eburnew. and B amphrtnt . Ot 

North Inlet balanid examined, only Chelombra patula 

and Conopea galeata larvae are con. i. tentl) larger 

(Table 15); B. trigonu have imilar ~ized larvae. 

Balanus eburneu Gould 

Balanu.s eburneus range from. 'e~ En land to BrazIl 

in the we tern Atlantic and occurs from lo~ \8ter to 3, 
Figure G.-BalanU8 venU8tU8. Naupliar antennule of stage I (A), II (B), III (C), IV (D), V (E), VI (F); naupliar mandible of stage II (G), III (H), 

IV (I), VI (J). Scale = 0.1 mm. 

10 
Figure 7.-Balanus venustus. Naupliar antenna ofstage I (A), II (B), III (C), IV (D), V (E), VI (F). Scale = 0.1 mm. 

11 
H 

F 

G 

Figure 8.-Balanus venustus. Abdominal process of stage II (A), III (8). IV (C). V (E. F). VI (G); labrum of stage I (H). II 

(I). IV (J). Scales = 0.1 mm. 

m (Henry and McLaughlin 1975). McDougall (1943) 

noted it is the most abundant intertidal barnacle at 

Beaufort, N.C. At North Inlet, B. eburneus is predominant on all intertidal wood structures from about midtide level and below. It rapidly fouls wood and plastic 

boat surfaces and is common on both intertidal and subtidal oysters. Intertidal specimens tend to be crowded 

and cylindrical in form while subtidal specimens, far less 

abundant, are conical. 

The larvae of B. eburneus have been reared and described by Costlow and Bookhout (1957) using eggs from 

adults collected at Beaufort. Larvae were also reared, but 

not described, by Freiberger and Cologer (1966) using 

adults collected at Miami, Fla. 

Numerous cultures of B. eburneus have been reared at 

South Carolina for this study and for work by Jorgensen 

(1976). Larval morphology closely matches results re12 

ported by Costlow and Bookhout (1957) in major features; however. numerous discrepancies in setation were 

noted. 

The shield of B. eburneus nauplii is plain in all stages, 

lacking dorsal or lateral shield spines. Morphological 

changes at each molt follow the normal pattern (Fig. 4). 

The fh are moderate in length and, beginning with stage 

II, are directed forward. The as margin is arched; the 

shield outline is smoothly elliptical (Fig. 9). 

Setal formulae for all stages (Table 6) follow the usual 

balanid pattern (Table 4). Based on present observations of four separate hatches, stage II setation described by Costlow and Bookhout (1957) does not appear 

typical. Plumodenticulate setae are present on the Mn 

endopods (stages IV-VI); up to four plumodenticulate 

setae may be present at stage VI. 
I 

I 

I 

\- \ ___ "I.._} I 

I 

'-"', 

• 

, 

I 

, l --' 

• 

e 

Figure 9.-Balanus eburneus. Shield outlines of stages II-VI (A-E); abdominal process of stage II (a), IV (c), 

V (d), VI (e). Scale = 0.1 mm. 

Table 6.-Setation formulae for nauplii of Balanus ebumeus. 

Stage An! An2 Mn 

VI S PPPSPPSPPPS S 4P8P PPSPP PSP PD PSCP G P4PP 4S SDSD DSCDP PCP G 

V SPPPSPPSPSP S 3P7PS PPSPP PSP PD PSCP G P4PS 4S SDSD DSCDP PCP G 

IV SPPSPP SP P S 2P6PP" PPSp' PSP PD PSCP G P4P 4S DSP DSCDP PCP G 

ill SPSPPSP P S 2P5P PP P PS PDPSCSG P3PS 3S PSS D CP PCPG 

IT SSPSSP P S SP4PS PP S PS PD P CS G P3PS 3S PS P CS PC G 

The DTS is distinctly longer than the AP in all stages 

(Fig. 9a-e). Abdominal spination is typical (Fig. 4); one 

median spine is present in stages IV and V. 

The lb is trilobed with a distinctly longer median lobe. 

Although the median lobe margin may have minor denticulation, no distinct teeth are present. 

Balanus eburneus nauplii are generally small, averaging slightly larger than B. a. amphitrite larvae (Table 

15). Size ranges of larvae reared at 25 0 C are similar to 

those reported by Costlow and Bookhout (1957) except 

for width: 

Balanus amphitrite amphitrite Darwin 

Balanus amphitrite amphitrite is a cosmopolitan species of warm and temperate seas. It is usually intertidal, 

often in brackish water. On the eastern coast of the 

United States, B. amphitrite is common from Florida 

13 

north to the Carolinas and has been reported as far north 

as Massachusetts (Zullo 1963). At North Inlet, it is a 

common intertidal species, generally situated between 

upper intertidal Chthyamalus tragilis and lower intertidal B. eburneus on wood pilings. 

The complex and often confused status of B. a. 

amphitrite has been reviewed by Henry and McLaughlin (1975). Of particular significance for a review of existing literature is the placement of B. a. communis, B. a. 

denticulata, and B. a. hawaiiensis in synonymy with B. 

a. amphitrite. 

Costlow and Bookhout (1958) described larvae reared 

from North Carolina adults. Larvae have also been described from Japan (Hudinaga and Kasahara 1942), Brazil (Lacombe and Monteiro 1972), and India (Pillai 1958; 

Karande 1973). Balanus a. amphitrite larvae obtained 

from numerous diet and temperature studies have been 

compared with these existing descriptions. 
B 

c 

-

E 

Figure IO.-Balanu8 amphitrite amphitrite . . hield outlinr, of naupliar taf( ,I-\'I (A-Fl; C) prid carapace 

profile (G); abdominal proce~, of stage II (al, IV (dl. \'1 (f). ,~'nle, = 11.1 mm . 

Balanus amphitrite nauplii lack dorsal or lateral shield 

spines, except for stage II. Stage II nauplii may have a 

pair of small blunt spines on the lateral shield margin 

(Fig. lOB). Morphological changes at each molt are typical (Fig. 4). At stage II, the fh extend nearly perpendicular to the shield midline; the fh tips often bend lightly 

rearward. This configuration remain consi tent in later 

stages (Fig. 10). 

Setation is typical (see Table 8). The An2 exopod etae 

of stage VI nauplii are variable (llP, llPS, 12P). Mandibular plumodenticulate setae are not well developed 

and only one such seta occurs consistently. 

The DTS is longer than the AP in all stages (Fig. lOa, 

d, f). Abdominal spination is typical; one median spme IS 

present in stages IV and V. 

The lb is trilobed; the median lobe normally extends 

slightly beyond the lateral lobes. All lobes have numerous simple setae, but no teeth are present. 

Balanus amphitrite larvae are small (Table 7), generally intermediate in size between Chthamalus /ragilis 

and B. eburneus (Table 15). The rearward orientation of 

the fh is the most useful character for recognition of later 

stage nauplii. Stage II nauplii are readily confused with 

those of B. improuisus; care must be taken to note the 

small lateral spines and lack of distinct labral teeth for 

B. amphitrite larvae. Cyprids are very similar to those of 

other amphitrite-complex species; no means to identify 

this stage to species has been devised. 

Present observations vary in numerous aspects from 

existing descriptions of B. amphitrite larvae. The size of 

larvae reported by all investigators (Table 7) is in general 

agreement, with two exceptions: the widths of all 

14 

. tage. are con i. tently reater in the study of Co tlow 

and Bookhuut (195 ) and the later tage IIY -VI) larvae 

reported by Pillal (195 ) are relatively mall and how 

little in rea. e per molt. lntere tingly, Pillai' work repre-

-ent the only·tudy u mg planktonic material: the maIler lze- could repre ent a real phenomenon. but observatIOnal error i more likely u ing planktolllc 

matenal. 

--etation of larvae does not completely agree III any 

tudy. It unfortunately i conjecture a to what degree 

thi repre ent ob ervatlOnal error in de criptions or real 

variation in the larvae. With the exception of the stage 

III ~ln exopod. pre ent etal count agree with tho e of 

Costlow and Bookhout (1958). The descriptions of 

Hudinaga and Ka ahara (1942) and Pillai (195 ) are sufficient to allow generation ot comparative setal formulae 

(Table 8). As indicated in the table. only three minor 

points of difference exist between the Japanese description and the present study. However. in the study by PiIlai. stage V and \1 setation how significant variation. 

This sheds further doubt on the accuracy of his plankton 

identification. 

Karande (1973) reports no median spine on the AP of 

stages IV and V. Hudinaga and Kasahara (1942) and 

Costlow and Bookhout (1958) make no mention of one, 

however. in agreement with present observations; Pillai 

(1958) reports a single median spine for both stages. 

Balanus improvisus Darwin 

Balanus improuisus occurs along the entire Atlantic 

coast of the United States and is found from the intertidal zone to 46 m (Henry and McLaughlin 1975). The 
Table 7.-Size of Balanus eburneus (top) and Balanus 

amphitrite (bottom) larvae reported from various 

sources: Costlow and Bookhout (1957) (BB); Costlow 

and Bookhout (1958) (CC); Hudinaga and Kasahara 

(1942) (HK); Karande (1973) (K); Lacombe and Monteiro (1972) (LM); Pillai (1958) (P); Sandison (1954) 

(S); and present results (PR). Total length (TL), shield 

length (SL), and width (W) in millimeters. 

Stage 

II 

III 

IV 

V 

VI 

II 

III 

IV 

V 

VI 

Source 

BB 

PR 

BB 

PR 

BB 

PR 

BB 

PR 

BB 

PR 

CC 

HK 

K 

LM 

P 

S 

PR 

CC 

HK 

LM 

P 

PR 

CC 

PR 

CC 

PR 

P 

CC 

PR 

P 

TL 

0.32-0.34 

0.32-0.36 

0.35-0.38 

0.36-0.41 

0.40-0.42 

0.42-0.45 

0.44-0.48 

0.46-0.57 

0.54-0.60 

0.57-0.62 

0.25-0.30 

0.26 

0.30 

0.31 

0.29 

0.32 

0.28-0.34 

0.30-0.34 

0.30 

0.38 

0.36 

0.31-0.36 

0.35-0.39 

0.33-0.40 

0.41-0.47 

0.40-0.47 

0.47-0.53 

0.47-0.57 

SL 

0.30-0.33 

0.30-0.33 

0.35-0.38 

0.33-0.44 

0.42-0.50 

0.39-0.46 

0.25-0.32 

0.24-0.30 

0.30-0.35 

0.28-0.35 

0.27 

0.35-0.40 

0.34-0.39 

0.29 

W 

0.21-0.23 

0.16-0.18 

0.23-0.27 

0.18-0.23 

0.27-0.32 

0.23-0.25 

0.29-0.34 

0.26-0.32 

0.36-0.39 

0.32-0.37 

0.19-0.24 

0.16 

0.15 

0.16 

0.16 

0.12-0.16 

0.22-0.27 

0.19 

0.17 

0.19 

0.16-0.20 

0.25-0.32 

0.17-0.23 

0.25-0.32 

0.24-0.28 

0.27 

0.35-0.43 

0.27-0.32 

0.27 

U ! 

• 

J 

• 

A 

• • 

• 

I 

\ 

Figure 1 I.-Balanus improvisus. Shield outlines of naupliar ,tage 

II-VI (A-E). Scale = 0.1 mm. 

species can WIthstand low salinities. is predominant in 

brackish water, and is often associated with B . . ubalbidus or, in Europe Elimimus modestu' (Jone and 

Crisp 1954). In North Inlet, B. improuisus wa. conspicuously absent in the major tidal creeks with. alinitie 

generally above 20%. but was common III waterway. 

draining abandcned ricefields and al 0 upper Winyah 

Bay, usually attached to concrete, bricks, or debri 

Table 8.-Setation formulae for nauplii of Balanus a. amphitrite as reported in different studies, 

Complete formulae for the present study (Pr) are given; differences from these formulae as derived 

from descriptions by Hudinaga and Kasahara (1942) (HK) and Pillai (1958) (PL) are noted, 

Stage Study AnI An2 Mn 

Pr SSP PSPP SP PPS S 3P 9P PPSPP PS PDPSCPG 

VI HK 

PL 3P7PSPP PP P4P 

Pr SSP PSPP SP S P S 3P 7PS PPSPP PSS PD PSCP G P4PS 4S P'P DSCP PCP G 

V HK PPSPP PP 

PL SPP PPSP PS 2P 6PS PP PP PP PDPPCPG P5P 

Pr S P PSPP SP PS 3P5P PPSP PS PDP CPG P':P 4 p'P D cPP PG 

IV HK SSP PPSP P PPSPP PP 

PL 2P6PS PP P PPCP P4P 

Pr SPSPP P PS 2P5P PP P P PD P~CP G P3P 3_ p', D CPPC'PG 

III HK S SP~ SP P PP ~ 4 PP. 

PL PP P P CP P~ 

II Pr 

15 
'D 

Figure 12.-Balanus improvisus. Antenna of stage IV (A); antennule of stage IV (B); labrum of stages II and IV (C); abdominal 

process of stage II (D), IV (E), V (F), VI (G). Scale = 0.1 nun. 

Balanus improvisus larvae were reared both from 

North Inlet and Rhode Island adults (Pettaquamscutt 

Pond) and compared with the excellent descriptions of 

planktonic larvae from the United Kingdom and Baltic 

regions (Jones and Crisp 1954). 

The shield of B. improvisus nauplii (Fig. 11) is without lateral or dorsal spines in all stages. Morphological 

development at each stage follows the expected sequence 

(Fig. 4); ps spines are present in stages IV-VI. The fh of 

stage II nauplii may extend nearly perpendicular to the 

carapace midline, much as in B. amphitrite, but more often are directed slightly forward. In stage ill larvae, the 

fh base extends at a slight forward angle, however, the 

top curves back. Frontolateral horns in stages IV-VI extend slightly forward similar to B. eburneus larvae. 

16 

Setation follows a normal pattern: the setal formula 

is nearly identical to that of B. eburneus (Table 6). Stage 

IV nauplii have five An2 endopod terminal setae (Fig. 

12A), as opposed to four setae in B. eburneus. As noted 

by Jones and Crisp (1954), the Mn endopod is relatively 

large (Fig. 12B); the Mn G is well developed. Up to four 

Mn plumodenticulate setae are present in stages IV-VI. 

The AP spination is typical (Fig. 12D-G). One pair of 

lateral series two spines and a small median spine are 

present in stages IV and V. The furcal stem is long; the 

AP and DTS are nearly equal in length in stage IV (Fig. 

12E) but the AP is usually longer in stages V and VI (Fig. 

12F, G). 

The lb (Fig. 12C) is trilobed; the median lobe extends 

beyond the lateral lobes. In South Carolina nauplii, the 
median lobe has a distinct pair of lateral teeth; two-four 

,maller median teeth are also present in earlier naupliar 

,tages. These teeth are less developed in Rhode Island 

nauplii and are easily overlooked; they are not described 

for European material (Jones and Crisp 1954). 

The larvae of B. eburneus and B. improvisus are very 

,imilar both in size and morphology. Stage II nauplii of 

these species are nearly the same size in South Carolina 

during the summer; however, Rhode Island nauplii and 

winter South Carolina stage II nauplii are noticeably 

larger (see Table 15). Later stages of B. improvisus tend 

to be larger but size ranges overlap. In stages II and III, 

the fh of B. improvisus, particularly the larger cool-water forms, tend to extend perpendicular to the shield; the 

fh of B. eburneus always extend distinctly forward. 

Balanus improvisus nauplii have distinct teeth on the 

median labral lobe, this in contrast to B. eburneus and 

B. amphitrite. In stages IV and VI, B. improvisus nauplii 

have a broad more rounded cs relative to B. improvisus 

and B. eburneus, the median AP spine is small or absent, and the AP and DTS are about equal in length. The 

cyprid of B. improvisus is quite similar in shape to other 

species of the B. amphitrite complex. Although often the 

largest sized cyprid in this species complex (Table 16), 

size ranges overlap and no means for positive identification is presently available. 

Balanus subalbidus Henry 

A recently described species (Henry 1973), B. subalbidus ranges from Massachusetts to Florida on the Atlantic coast (Henry and McLaughlin 1975). It is normally found in intertidal brackish water habitats. No 

specimens were found in North Inlet, but numerous individuals were collected from intertidal debris at Winyah 

• 

• • • • 

E 

Bay sites. Identification of ample wa. pro\ ided by D fa 

Henry. 

Larvae of B. subalbldu..s have not been pr viously 

reared or described. The following de cription are ba d 

on a small number of larvae succe fully reared to tag 

VI nauplii. The cyprid stage wa not obtained nor \\ere 

additional hatche obtained to verify re ult . 

Balanus subalbidus are generally mall and narrow. 

Early stages average about the arne ize a B. amphitrite nauplii, but late stages approach or surpa. sizes 

observed for B. eburneus larvae reared under imilar 

conditions (Table 15). 

In general appearance, but not ize, B. ubalbidw. 

nauplii resemble those of Semibalanus balanoides. The 

carapace is long and narrow with very short, straight fh 

(Fig. 13). No lateral or dorsal hield spines are pre ent. 

The ventral shield spines (stages IV-VI) are long, delicate, and often curved outward. 

Setation is virtually identical to that ob erved for B 

amphitrite (Table 8). Only the An2 of stage IV varie. 

from B. amphitrite; nine plumose setae are on the exopod, but only two postaxial setae are pre ent on the 

terminal endopod segment (3P:6P-PP P':P ;PD; 

PSCP:G). 

The trilobed Ib has a distinctly longer median lobe in 

all stages (Fig. 13F). No teeth or spines were observed. 

The AP is relatively small; the furcal stem i exceptionally short, the maximum observed length being indicated in Figure 13G. In all stages the DTS is distinctly 

longer than the AP. Abdominal spination is typical: one 

lateral pair of series two spines but no median spine are 

present in stages IV and V. 

The narrow shield and short fh readily distinguish B 

subtJlbidus from all South Carolina species except perhaps B. amphitrite. Care must be taken to note the longu 

F 

17 

Figure 13.-BalanU8 ,ubalbidU8 . • h Id OUllin of 

naupliar stage II-VI A-E), I brum of lall 1\ (FI, 

abdominal proce. of taKe n (Gl 
Balanu Twin 

• • 

A 

B 

1J. 

• 

II and III of B 

ae r adily dL tinnd vef) ~hort AP 

• 

I 

loger 1. 66) reared lan'ae from ~liami. and Barker 

(l i ') reared and de cribed lan'ae from ~ew Zealand. 

Pre"ent result- are ba-ed on lan'ae reared at 25°C from 

a single hatch released from a • 'orth Inlet adult. 

Bo/anu tr( onu nauplii lack dorsal or lateral hield 

_pine~ in all tages (Fig. 14) .. Morphological change at 

each molt are con i tent with the expected pattern (Fig. 

4 . At -tage II. the fh are directed lightly rearward; in 

'ubsequen t tage the fh extend anteriorly. The hield of 

.tages IV-\l i broad with a moderately arched dor al 

surface; the paired p pme are well-developed. The 

cyprid is large (see Table 16) wIth a distinct carapace 

profile relative to other Carolina specie (Fig. 36). The 

anterior carapace region is wide and well-rounded; a 

somewhat ··teardrop" shape re ults. 

~ etatlOn (Table 9) follow the typical balanid pattern 

although orne minor variations were noted . Denticulate 

I ij,(ur(' II - BallinUR trigunuH. Shield outlines or nau· 

plillr ,tagl's 11·\1 ( \ -F). Scall' 0.1 mm 

'a' n r rmula tor n uplll or flalanu. tri on .... 
igure IS.-Balanus trigonus. Antenna of stage V (A); mandible of 

stage V (B). Scale = 0.1 mm. 

setae are well developed on stages V and VI Mn (Fig. 15); 

one terminal endopod is denticulate in these stages, a 

feature not observed in other species described. 

The AP is shorter than the DTS in stages IV-VI (Fig. 

lWa-c), but is about equal in length for stages V and VI 

Fig. 16d-e). Abdominal spination is typical in stages ll-

[V (Fig. 16A-C); stage IV has one median spine. Series 

wo spines of stage V (Fig. 16D) consist of two pairs; one 

arge and one small median spines are also present. 

The trilobed lb has a distinctly longer median lobe in 

all stages (Fig. 16F). No teeth or denticulation is evident 

on labral margins. 

Balanus trigonus larvae are large relative to most 

warm-water species; only Chelonibia patula larvae attain a similar size for South Carolina species (Table 15). 

In addition to the generally large size, the broau yet relatively flat shield with well-developed ps spines distinguish later stage nauplii. Stage II nauplii have "swept 

back" fh similar to B. amphitrite but B. trigonus larvae 

are distinctly larger. 

19 

Conopea galeata (Linnaeus) 

Conopea galeata is a commensal on gorgonians and is 

restricted to warmer waters. In the western Atlantic it occurs as far north as North Carolina (McDougall 1943). 

Dead individuals are common on gorgonian branches 

washed ashore on South Carolina beaches. Several 

gravid individuals were dredged from tidal creeks at 

North Inlet, but most gorgonians collected within the inlet are free of commensal cirri peds. 

Larvae of C. galeata have been reared and described 

by Molenock and Gomez (1972) using adults collected on 

the California coast. Present rearing attempts yielded 

stages I-V; stage VI and the cyprid were not obtained. 

For the stages obtained, no significant variation was observed relative to Pacific larvae. 

All Atlantic larvae were within size ranges cited by 

Molenock and Gomez (1972). Assuming VI and cyprid 

stages also fall within these ranges, the mean sizes of C. 

galeata larvae closely resemble those for B. uenustus larvae (see Table 15). 

The stage I nauplius (Fig. 17 A) shows no distinguishing characteristics. Stage II nauplii are quite distinctive; the shield has numerous short lateral spines (Fig. 

17B) and a large median dorsal spine (Fig. IB). Later 

stages have two large dorsal spines (Fig. IF) and numerous lateral spines. Frontolateral horns are long and, 

in stages ill-VI, directed forward. Posterior shield spines 

are long and curve slightly outward. 

The AP spination differs little from the normal balanid pattern. A single pair of series one spines is present 

in stages II and ill, however, additional spines are well 

developed on the furcal spine (Fig. 17F, H). Series two 

spines consist of one lateral pair and one median spine in 

stage IV, two lateral pairs and one median spine in stage 

V, and six lateral pairs in stage VI. One pair of series 

three spines are present in stages V and VI. 

The trilobed lb (Fig. 17E) has a distinctly longer median lobe. A small spine is present on the median lobe of 

stages II-V in Atlantic larvae and assumed to be also 

present in stage VI. 

Setation observed agrees closely with the formulae 

given by Molenock and Gomez (1972). With the exception of only 10 plumose setae on the endopod of stage V 

An2 and 11 plumose setae on stage VI, the formulae for 

C. galeata are the same as that for B. amphitrite (Table 

8). Plumodenticulate setae not noted by Molenock and 

Gomez were observed on the mandibular endopod. 

Larvae of C. galeata most closely resemble B. uenustus larvae. The large dorsal spine(s) present in all but 

stage I nauplii readily distinguishes this species from 

other North Inlet larvae. 

Chelonibia patula Ranzani 

Chelonibia patula is cosmopolitan in tropical and 

temperate waters. On the eastern coast it is not normally found much north of the Delaware Bay. Originally 

reported only from the carapace of crabs (Pilsbry 1916), 
A 

v • 

v • 

r • 

y v 

r ~ 

b 

Figure 16.-Balanus trigonus. Abdominal process of naupliar stage II (A. a). III (B. b). IV (C. c). V 

(D. d). VI (E. e); labrum of naupliar stage IV (F). Scales = 0.1 mm . 

the species will also settle on shells (Pils bry 1953). In 

North Inlet, it is quite common on horseshoe crabs and 

often found on portunid and spider crabs. Large healthy 

specimens were also found on hermit crab shells, supporting Pilsbry's later observation. 

Coker (1902) reported rearing barnacle larvae from 

adult acorn barnacles attached to blue crabs, but neither 

the species nor results were documented further. 

Lacombe (1973) attempted to rear C. patula but ob20 

tained only stages I-III. I reared two separate hatches to 

cyprid stage. As this represents the first complete larval 

development reported for this genus, a detailed description follows. 

Stage I. (Fig. 18B). Rather robust and large with dark 

brown pigment outlining gut region. Otherwise larvae are 

typically pear-shaped with folded fh and rudimentary 

AP. 
• 

A 

• 

U 

E F G 

H 

D 

Figure 17.-Conopea galeata. Shield outlines of naupliar stages I-IV (A-D); labrum of stage IV (E); lateral 

view of stage IV dorsal shield spines, DTS, AP (F); abdominal process of stage II (G), IV (H). Scale = 0.1 mm. 

0 9 u 

'f'. ' • '. .' u 

, " 

, u 

E 

H 

Figure 18.-Chelonibiapatula. Egg ready to hatch (A); shield outlines ofnaupliar stages I-VI (B-G); carapace profile of cyprid (H). Scale = 0.1 mm. 

21 
ta J1 Fin. 1 ). Cephalic hield outline i nearly 

clrculllI v.,th a hi hI)' arched back. Frontolateral hom 

ar I n with a ~light torn'ard orientation. Pigment 

ar und t i pre ent and persi ts in all naupliar tage . 

ta~e III Fi I-D. imilar to tage II; anterior 

hleld margm Ie. convex and tb wider with plit tip. 

1 xillul are pre .ent. The AnI ha one preaxial seta. 

ta e l\. (Fig. 1 E . Po'terior hield margin pre ent 

With hort cl ,el' paced p pine. The AnI has two prelal etae . 

. ta \ (Fig. 1 -F). imilar to tage I\'. -'eries three 

pm pr ent on AP. The AnI has three preaxial setae. 

'ta \ I (Fig. 1 G). P terior shield region some-

\lih t elongat d and narrow. Compound eye are present 

ft r 1-2 da\' . The AP ha ix pairs of erie two spines. 

Cjpnd ·Flg. 1 HJ. Large and wide with relatively 

Vi 11-( ev loped compound eye . Anterior ventral carapa e maTf~1n tend to have traight margin while antenor do al margin I rounded. 

The 'hield in all tage lack lateral or dorsal spines, is 

b ad and nearly circular, and ha a highly arched doral urface A di tinct dark brown pigment area rings the 

gut In all naupliar tage (Fig. 34A). 

etal numbers clo ely follow the normal balanid pattern (T ble 4, however, etal types vary (Table 10). All 

Anl pr a ial 'etse are imple and only one AnI terminal 

ta I plumo e in tage ill-VI (Fig. 19). This is in 

mark d contra t to all other 1 'orth Inlet species in which 

m pr aXial etae are plumo e and three (rarely two) 

rmmal etae are plumo'e in later naupliar stages. The 

An2 (FIg _0) .etatlOn i tYPical, although terminal setae 

th ndopod have Ie plumo e types than ob erved in 

m t p Ie. 'I he ~ln (Fig. 21) terminal exopod seta is 

p rtl ul r1) tout wit h den e long etule on the basal reth haft. The first po taxial etal group of the 

d h t .... o di. tinct plumodenticulate setae in 

Iv vI (hg. 2lD). 

PI dl tlnctly horter than the DT ' only in tage 

In I ter tag the PI. ubequal or longer (Fig. 22). 

In Al pin tl n i not typical. In addition to what norm II n Id red the erie one lateral pine pair, 

nd III hs\ n dditional pine pair on the furF I 22 , B). ~t8ge IV ha one lateral pair of 

nd s c mplex of two mall median 

pinule (Fig. 22 ). tage V ha 

rl tw and erie;; thre plne~ and a 

lat ral and mall median .'pine 

of pine. in ~tage' IV and 

not normally de ribed in 

rl p 1'-3; ~10)' e 1 1). 

Figure 19.-Chelonibia patula. Antennules of naupliar stages I-VI 

(A-F). Scale = 0.1 mm. 

The trilobed lb is typical in form for Balanus spp. (Fig. 

22F-H). The longer median lobe lacks spines or denticulation in all stages. 

Larvae are quite large for tropical species and have the 

largest average size of described North Inlet species (see 

Table 15); only Balanus trigonus has larvae of comparable size. The large well-rounded carapace and pigmented gut region readily distinguish C. patula nauplii 

from other Carolina species of cirripeds. The size (see 

Table 16) and large compound eye of the cyprid may be 

sufficient to identify this stage. 

Chthamalus fragilis Darwin 

Chthamalus tragi/is occurs from Cape Cod south to the 

We t Indies ( ewman and Ro s 1976), normally on upper intertidal ub trate . In North Inlet, C. {ragilis is 

mo t common on hard substrates (wood, plastic, concrete, et .) at the highe t intertidal levels, but cattered 

individual are often intermixed with B. amphitrite and 

B eburneus at lower level . It i also commonly found on 

.'partlna leave and talks. 

labl IU.- lion formula for naup!ii or Ch lonibi4 patula. 
Figure 20.-Chelonibla patula. Antennae of naupliar stages I-VI (A-F). Scale = 0.1 mm. 

Larvae of the closely related C. stellatus have been de-

~cribed (Table 2), but no published descriptions of C. 

ragilis exist. 

The nauplii and cyprid of C. fragilis are small; average 

measurements are the smallest of South Carolina species (see Table 15). Since the AP of later stages usually 

contracts beneath the posterior carapace margin, total 

lengths for stages IV-VI have been omitted. 

Stage I nauplii are small and typically pear-shaped 

Fig. 23A). However, stage II and later stages have a 

road nearly round shield with very short fh somewhat 

folded under the as margin (Fig. 23G-F).The shield has a 

highly arched back (Fig. 23b d) and late stages appear 

"globular." No shield spines are present and the ps 

~pines typical of balanids are lacking. The cyprid (Fig. 

Q3G) is similar to B. eburneus or B. amphitrite but 

smaller (see Table 15). 

Setal counts of the AnI and Mn follow the balanid patfern (Table 4). The AnI (Fig. 24A) terminal setae vary 

23 

between SSPS or PSPS in later stages (Table 11), a 

situation unique to South Carolina species observed. The 

An2 (Fig. 24B) is unique, having hispid setae, large numbers of postaxial endopod setae (Table 11) and " feathered" or "downy" plumose setae. The Mn (Fig. 24C) 

cuspidate setae have dense setulation (Fig. 31) relative to 

equivalent setae in balanids (Fig. 3H). Plumose setae associated with the cuspidate setae also have dense setules 

but are not "feathered." 

The AP of stages II and ill is short with strong furcal 

spines and large series one spines (Fig. 25A, B). Later 

stages depart from AP configuration of balanids. In stage 

IV, one pair of large spines splits from the furcal stem. 

The resulting configuration appears as four terminal 

spines or processes (Fig. 25C). In addition, two pairs of 

lateral spines are evident on the abdominal region . Stage 

V is similar, but an additional pair of median spines is 

present between the terminal processes (Fig. 25D). Stage 

VI (Fig. 25E, F) also has six terminal processes and two 
pairs of lateral spines and, in addition, four pairs of median spines are present. The DTS is longer than the AP 

in stages II and ill (Fig. 23b), subequal in stage IV (Fig. 

23d), and very short or rudimentary in stages V and VI 

(Fig. 26F). 

The lb is unilobed . Stages II and ill have one pair of 

larger lateral teeth separated by numerous small denticules (Fig. 26A). The denticles are lost in stage IV (Fig. 

26B) and a median porelike protuberance becomes increasingly developed in the late st ages (Fig. 26C). 

Chthamalus fragi lis larvae have features noted as typical for other larvae ofthe genus: no ps spines; fh folded 

under the shield; a carapace nearly as broad as long; a 

unilobed Ib; and hispid and feathered setae (Sandison 

1967). 

The general appearance of the nauplii and small size of 

the cyprid make larvae of this species quite easy to distinguish in North Inlet, where no other chthamalid species occur. 

24 

Figure 21.-Chelonibia patuw.. Mandibles of naupliar 

stages I-VI (A-F). Scale = 0.1 mm. 

Octolasmis muelleri (Coker) 

Octolasmis muelleri is a small pedunculate barnacle 

found attached to the gills of the blue crab, Callinectes 

sapidus, and other decapod hosts (Walker 1974b). First 

described from Beaufort, N.C., by Coker (1902), O. 

muelleri is perhaps synonymous to the cosmopolitan 

Octolasmis lowei (Nilsson-Cantell1927; Causey 1961) or 

a local race or subspecies (Pilsbry 1953) of a shallow-water O. lowei-series (Table 12). In the western Atlantic its 

known range extends southward from the Chesapeake 

Bay through the Gulf of Mexico and Caribbean Sea to 

Brazil (Lang 1976). 

The complete larval development of this species has 

been recently described using larvae released from North 

Inlet adults (Lang 1976). An additional octolasmid species, Octolasmis forrestii (Stebbing), has subsequently 

been obtained from the gills of a spiny lobster captured 

in Belize, Central America; released larvae were suc-
I, ,) 

V 

V Figure 22.-Chelonibia patula. Abdominal process of 

stage II (A, a), III (B, b), IV (C, c), V (D, d), VI (E); 

labrum of stage II (F), IV (G), VI (H). Scale = 0.1 mm. 

E 

~essfully reared through stage VI nauplius. A brief comoarative account of the larval development of both OctoI mis species follows; for details see Lang (1976). 

Larvae of O. forrestii are quite similar to O. muelleri 

Figs. 27, 28). The nauplius cs is small and triangular 

and develops small blunt lateral spines in later stages. 

rhe AP and DTS are considerably longer than the shield, 

and the fh are also quite long. In both species development of the ps border is delayed until stage V. 

The appendages of octolasmid nauplii are distinctive. 

he AnI and An2 are elongate relative to balanomorph 

nauplii while the Mn is small with a poorly developed 

exopod (see Figs. 33A, 34C). Setation of O. forrestii 

nauplii differ from those of O. muelleri (Table 13) only at 

stage IV (Fig. 29). Bristled setae (Fig. 3M) are present on 

the AnI (Fig. 29A); development of setae at each molt, 

however, follows a pattern similar to balanomorph 

nauplii. The An2 exopod setae are long and delicate; unlike balanomorph species, setules are restricted to one 

side of the' shaft for these setae. The Mn (Fig. 29C) shows 

little increase in size during molts; exopod setation 

(Table 13) is significantly reduced in later stage nauplii 

relative to all other described planktotrophic cirriped 

nauplii. 

The AP and DTS of octolasmid nauplii are extremely 

long, a feature also seen in Lepas nauplii (see Fig. 30). 

25 

Unlike Lepas nauplii, larvae of both Octolasmis species 

lack abdominal spines. 

The lb of O. muelleri and O. forrestii is unilobed and 

tapers to a median porelike structure. No teeth or denticulation were observed (Fig. 29D). 

Development of O. forrestii nauplii incorporates the 

same unique features described for O. muelleri (Lang 

1976). Morphology and naupliar size of these two species 

varies little; identification to species from field samples 

would be virtually impossible in areas where numerous 

Octolasmis species occur. In coastal Carolina waters, 

however, O. muelleri is the only octolasmid species commonly present. Only Lepas nauplii are similar in appearance; size and lb morphology easily distinguish these 

larvae. Although the nauplii of O. muelleri are distinctive, the cyprid (see Fig. 36C) closely resembles Balanus 

amphitrite-complex cyprids. Identification is possible 

based on the symmetric carapace profile of O. muelleri 

cyprids as opposed to the enlarged anterior region and tapered posterior region common to Balanus species. 

Lepas spp. 

Five species of Lepas are commonly found in the western Atlantic (Zullo 1963). All are open water neustonic 

forms whose occurrence in coastal waters is usually 
• • 

G 

Figure 23.-Chthamalus fragilis. Shield outlines ofnaupliar stages IV! (A-F); lateral profile of stage II (b), IV (d); carapace outline of 

cyprid (G). Scales = 0.1 mm. 

restricted to introduction by ships or floating debris 

directed shoreward by storms. Collections on South 

Carolina beaches following storms have produced Lepas 

anatifera on driftwood and L. anserifera, L. pectinata, 

and L. fascicularis on sargassum. Lepas hilli, although 

not observed in present collections, should also occur on 

occasion. 

Although breeding populations of Lepas are not commonly found in coastal waters, circumstance introduction of gravid adults may result in local release of Lepas 

larvae. The complete larval development of L. fascicularis has been reconstructed from plankton samples 

(Willemoes-Suhm 1876; Bainbridge and Roskell 1966). 

John Moyse reared nauplii of L. pectinata and L. anatifera (pers. commun.) but larvae remain undescribed. In 

present studies up to stage V nauplii of L. pectinata and 

stage m nauplii of L. anserifera have been reared from 

gravid adults washed ashore. Larvae obtained are quite 

similar to those described for L. fascicularis. Staging of 

Figure 24.-Chthamalus fragilis. Antennule of stage IV (A); antenna of stage IV (B); mandible of stage IV (C). Scale = 0.1 mm. 

Lepas larvae is not difficult (see Bainbridge and Roskell 

1966); however, identification of nauplii to species must 

await further descriptions of Lepas larvae. Using L. pectinata as an example, general features of Lepas nauplii 

are outlined below. 

Lepas nauplii have very long fh, a DTS, and an AP 

(Fig. 30A-C). The shield of stage n nauplii is plain (Fig. 

Table 11.-Setation formulae for nauplii of Chthamalus fragilis. 

3tage 

VI 

V 

IV 

ill 

n 

Ani 

S P P PSPP SP P PS S 

S P P PSpps SP S P S 

S P PSPP' SP P S 

SPSPSPSP P S 

SSPS SS P S 

4P8P 

4P7P 

3P6P 

2P5P 

SP4PS 

An2 

PPSPP PSSSS SFFF SPFH G 

PPSPP PSSS SFFF SPFH G 

PPSPS PSS SFF SPFH G 

PP P PSS FF SFH G 

PP S SS FF SFHG 

26 

P5P 

P4PS 

P4P 

P3PS 

P3PS 

Mn 

SSSS SPSP PSCP PPC G 

4S SPSP PSCP PPC G 

4S SP P PSCP PPC G 

4S SP P CP PPC G 

3S SP P CP PCG 
E 

Figure 25.-Chthamalus tragilis. Abdominal process of stage II (A), 

III (B), IV (C), V (D), VI (E); lateral profile of stage VI nauplius (F). 

Scale = 0.1 mm. 

30A, B). Later stages have dorsal and lateral shield spines 

and often appear quite "ornate" (Fig. 30C). The densely 

spinose AP is highly arched in early stage nauplii (Fig. 

30A, B); abdominal spines are present (Fig. 30D, E) and 

may be used to stage nauplii (Bainbridge and Roskell 

1966). The Ib is broad edged with one or more pair of 

teeth (Fig. 30F). Setation includes bristled setae on the 

An1 (Fig. 30G) and feathered setae on the An2 (Fig. 

30H). The Mn is well developed with notably long 

postaxial en do pod setae (Fig. 301). 

Nauplius SC 

Figure 26.-Chthamalus fragilis. Labrum 

of stage III (A), IV (B), VI (C). Scale = 0.1 

mm. 

Examination of plankton samples taken 2 to 35 mi off 

Georgetown Harbor, S.C., during October 1976, yielded 

stages II-VI of an undescribed cirriped larva. The predominant barnacle larvae present in all samples examined have been designated "nauplius SC." 

The elongate form (Fig. 31) and size (see Table 15) of 

nauplius SC resembles Octolasmis larvae, however, the 

AP (Fig. 31) varies significantly. The fh are moderate in 

length and directed rearward. Basic morphological 

changes at each molt closely follow the expected balanid 

pattern. 

Setation (Table 14) is unique. The An1 (Fig. 32A) is 

typical and shows a normal setation progression at each 

molt. The An2 (Fig. 32B) endopod has feathered setae 

and large numbers of setae in later stage nauplii. The Mn 

(Fig. 32C) is well developed with typical setation patterns. 

The DTS is long in all naupliar stages, a feature also 

seen in Lepas, Octolasmis, and Verruca (LeReste 1965) 

Table 12.-Structure of the Octolasmis lowei-complex. 

Synonyms of Octolasmis lowei Darwin-Nilsson·Canteli (1927) 

Dichelaspis lowei Darwin, 1851 

Dichelaspis darwini Filippi, 1861 

Dichelaspis aymonini Lesson, 1874 

Dichelaspis neptuni Mac Donald, 1869 

Dichelaspis sinuata Aurivillius, 1894 

Dichelaspis trigona Aurivillius, 1894 

Dichelaspis mulleri Coker, 1902 

Dichelaspis vaillantii Grovel, 1902 

Octolasmis geryonophila Pilsbry, 1907 

Madeira 

Mediterranean 

Japan 

Australia 

Java Sea 

Java Sea 

North Carolina 

Suez 

Atlantic 

Subsequent Modifications and Additions 

O. aymonini·reinstated as species 

O. brevis· Pearse, 1951 added as synonyms 

O. uncus· Pearse, 1951 

O. neptuni·reinstated as species 

O. geryonophila-changed to synonym of O. aymonin 

27 

Hiro (1937) 

Newman (1961) 

Newman (1961) 

Newman (1967) 
B 

D 

E F 

G 

Figure 27.-0ctolasmis muelleri. Shield outlines of naupJiar stages I-VI (A-F); c)'prid (G). ale = 0.1 mm. 

V A 

c o 

B 

E 

Figure 28.-0ctolasmis forrestii. Shield outlines of naupliar stages I-VI (A-F). Scale = 0.1 mm. 

28 
Table 13.-Setation formulae for nauplii of Octolasmis muelleri. 

Stage AnI An2 Mn 

VI S P P SBSS B P B S3P 7P 4P 2P S SSC G SSS 3S CPP PPP G 

V SP PSBSSBSB S2P7P 4P 2PSSSCGSSS 3SCPPPPPG 

IV PP SBSS B B 2P 5P2S 3PS PS S SSC G SS 3S CPP PPP G 

ill P SPSS B B 2P 5P 3P P S S C G SS 3S CPP PPP G 

IT SPSS B B SP 4PS 2PS S S S C G SS 3S CPP PP ? 

I SSSS S S SS SSS 3S SSG SS SS SSS SS 

B 

nauplii. The AP, however, is unique; a narrow stem is absent as the basal region splits directly into the furcal processes (Fig. 31). Abdominal spination is restricted to one 

large median spine in stages IT-V (Fig. 31A-D) and six 

smaller paired spines in stage VI (Fig. 31E, e). 

The lb (Fig. 31) is unilobed and tapers to a blunt denticulate tip in all stages. 

Larvae of this unknown species were not found within 

North Inlet or Winyah Bay but were common (in October) in nearshore waters. The general body form and unique AP structure of this nauplius readily distinguishes it; 

however, larvae of this species do not closely match larvae of any presently described family (Table 2). Possible 

affinities of these nauplii are discussed later. 

Hansen . (1899) described 10 "species" of cirriped 

nauplii from material collected by the PlanktonExpedition. Based on carapace, DTS, and labrum morphology, Hansen's "nauplius" may represent stage ill 

and IV of nauplius SC or at least a closely related species. 

Similarly "naupliusa" probably represents a stage VI 

Balanus trigonus nauplii and "naupliusi3" appears to be 

stage IV and VI Balanus amphitrite nauplii. However, 

29 

Figure 29.-0ctolasmis forreBtii. Antennule of stage 

IV (A); antenna of stage IV (B); mandible of stage IV 

(C); labrum of stage IV (D). Scale = 0.1 mm. 

since Hansen did not describe appendages and other 

naupliar detail, comparisons with present descriptions 

are tenuous. 

KEYS TO THE BARNACLE LARVAE 

OF THE CAROLINAS 

Assigning Stages 

Based on reared and planktonic material, it is possible to construct a key to the predominant barnacle 

nauplii of the Carolina coastal waters. The key is limited 

to naupliar stages IT-VI: stage I nauplii show little 

morphological variation and are rarely encountered in 

plankton samples while many cyprids (see page 36) cannot be reliably identified to species. A two-step procedure is followed. Since each naupliar stage often has its 

own set of morphological features and size ranges, 

nauplii must first be accurately "staged." Different keys 

for each stage or group of stages are then used to identify 

the species of the nauplius. 
A c c 

E 

F 

Figure 30.-Lepas pectinata. Shield outline of naupliar stage II (A); shield outline (B) and lateral profile (b) of stage III; shield outline (C) and 

lateral profile (c) of stage IV; abdominal spines of stage II (D) and stage IV (E); labrum of stagef II and IV (F); antennule of stage IV (G); antenna of stage IV (H); mandible of stage IV (I). Scales = 0.1 mm. 

Morphological features cited below for assigning stages 

of barnacle nauplii are shown in Figure 4. Abdominal 

process characters normally apply only to balanomorph 

larvae; other features are valid for all larvae except 

Octolasmis. In this case only the setation of the AnI is 

valid. See Figures I and 4 for a complete list of terms and 

abbreviations. 

30 

la. Frontolateral horns folded back, AP rudimentary ....................... . ....... Stage I 

lb. Frontolateral horns extended, AP well developed....... .. ...... . .. ................. 2 

2a. Posterior shield margin absent .............. 3 

2b. Posterior shield margin present. . . . . . . . . . . . . . 4 
A B : c 

E 

Figure 31.-"Naurlius SC." Shield outlines of naupliar stages II-VI (A-E) and lateral profiles of stages V (d) 

and VI (e). Scale = 0.1 mm. 

Table 14.~etation formulae for nauplii Y. 

Stage AnI An2 Mn 

VI S P P PSPP PP P PS P 4P8P PPSPPS PPPS SFFF PFSC G P5P PPSPPS PSPS SPCP PPP G 

V SPPPSPPSPSP P 3P8P PPSPP PPP SFFF PFSC G P4PS PPSPP PSPS SPCP PPP G 

IV SPPSPP SP P P 2P7P PPSPS SPP SFF PFSC G P4P SPSPS PSP SPCP PPP G 

III SPSPP SP P P 2P5P PP P 

II SSPS SP S S 2S4PS PP S 

3a. Frontolateral horn with plain tip, An1 

with!3ut preaxial seta ................... Stage II 

3b. Frontolateral horn with split tip, An1 

with one preaxial seta .... . .. ..... ..... Stage III 

4a. Compound eyes often present; thoracic 

region with six pairs of median spines; 

third An1 segment expanded ........... Stage VI 

4b. Compound eyes not present; thoracic region with 0-2 rows of spines; third An1 

segment not expanded. . . . . . . . . . . . . . . . . . . . .. 5 

PP 

SP 

31 

FF PFSCG P3PS SP SP P P PCPPPPG 

FF SF CG P3PS SS SSP PCPPP G 

5a. An1 with two preaxial setae, AP with 

series two spine pair ................... Stage IV 

5b. An1 with three preaxial setae, AP with 

series two and series three spine pairs ..... Stage V 

Species Identification of Nauplii 

Stage II nauplii are in many instances the most commonly encountered larval stage in plankton samples 

(Lang see footnote 3) and for this reason complete figures 
\ 

D 

\ 

I 

E 

32 

Ill(ur :12. •• lIuphu (." \nlennule of laKe III (/\); anlenna or 

,I'K 1/1 (H): mandible of I e III ( C I. al - 0. 1 mm . 

Figure 33.-Slage II nauplli of BalanUJI amphitritecomplex species common in Carolina waters: BalanUJI 

eburneUJI (A); B. improvisUJI (B): B. amphitrite amphitrite (C); B. BubalbidUJI (D); B. venUJItUJI (E). Scale 

= 0.1 mm. 
• C 

I 

, 1_ ... - _ ~(..-

J 

H 

Figure 34.-Stage II nauplii of barnacle species found in Carolina waters: Lepas pectinata (A); Lepas anseri-

{era (B); Chelonibia patula (C); "nauplius SC" (D); Conopea galeata (E); Chelonibia patula (F); ChthamalUll 

{ragilis (G); Balanus trigonus (H). Scale = 0.1 mm. 

or common stage II nauplii are provided (Figs. 33, 34) 

d the stage II key should be studied prior to use of later 

stage keys. 

The present keys should account for most barnacle larae found in shallow-water regions from Georgia to North 

Carolina. As evident by "nauplius SC," some undescribed nauplii can be expected, particularly in offshore 

samples. Difficulties in species identification of nauplii, 

for the most part, is limited to Balanus amphitrite-complex species (Fig. 33). Early stages of B. eburneus, B. 

improvisus, and B. amphitrite are particularly difficult 

to distinguish and may be easily confused. 

The size 'of nauplii, in many instances, provides rapid 

clues to both stage and identity of the specimen, however, caution should be exercised. Laboratory rearing 

clearly demonstrates that significant size differences in 

larvae may be induced by the temperature of egg incubation and/or larval rearing (Lang see footnote 3). Sizes 

ofnauplii (Table 15) and cyprid (Table 16) show that lar33 

vae developing in warmer water tend to be smaller than 

larvae of the same species developing in cooler water. 

Summer and winter stage II nauplii of B. improul~us 

from North Inlet plankton samples and summer larvae 

from Rhode Island show considerable size variation; both 

seasonal and geographical size variation should be expected. 

Key to Stage II Nauplii of the Carolinas 

1a. Labrum unilobed (Fig. 26) ............... 2 

lb. Labrum trilobed. . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

2a. Shield rounded. DT horter than 

shield length (Fig. 34G) . .. ... Chthamalu, fragill 

2b. Shield triangular. DT longer than 

shield length .... . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

3a. Labrum with flat toothed edge (Fig. 

35a. 34A. B) .... ... . .. .....•........ Lepa ... pp 

3b. Labrum tapered to blunt tIP (FIg. 35A) ...... . 
Table IS.-Size ranges of barnacle nauplii obtained by laboratory rearing and plankton samples. Measurements represent millimeters/IOO (38 

= 0.38 mm); n = number measured, TL = total length, SL = shield length, W = width; SC = North Inlet, South Carolina; RI = arraganllett 

Bay, Rhode Island. See Materials and Methods for diet symhols. 

Species 

Balanus 

amphitnte 

Balanus 

eburneus 

Balanus 

improvisus 

Balanus 

subalbidus 

Balanus 

trigonus 

Balanus 

venustus 

Chelonibia 

patula 

Conopea 

galeata 

Chthamalus 

tragilis 

Octolasmis 

muellerz 

NaupliusSC 

Source 

SC 

SC 

SC 

SC 

RI 

SC 

RI 

SC 

SC 

SC 

SC 

RI 

RI 

Diet 

Temp (0C) 

TET/MON 

25 

TET/MON 

25 

Plankton 

July 

TET/3H 

25 

TET/MON 

20 

Plankton 

Jan. 

Plankton 

Nov. 

TET/MON 

25 

TET/MON 

25 

TET/MO 

25 

Plankton 

July 

TET/SKEL 

20 

Plankton 

Oct. 

3H/MON 

SC 25 

(Molenoch and 

Gomez 1972) 

TET/MO. 

SC 

SC 

SC 

25 

TET/MO 

27 

Plankton 

Oct. 

Stage II Stage III tage IV Sta!(e V tage VI _ 

n TL W n TL W n TW SL W n TL SL W n TL 5L W 

2928-3412-16 27 31-3616-20 13. 33-40 24-3017-23 12 40-47 28-252428 10 47-57 34-3927-3 

1032-3616-18 10 36-41 18-23 10 42-45 30·3323-25 15 46-57 3.3-4426-32 15 57-62 39-4632-3 

831-3315-17 7 37-4120-22 10 28-3222·24 7 37-4028-30 42 

1528-3113-14 10 32-3816-19 10 41·46 29-3224-27 10 52-62 37-4132-35 10 6.5-72 48-5240-

1034-3716-18 10 37-4319-21 10 41-46 29-3225-28 10 51-60 39·4332-36 10 63-76 

10 35-38 16-18 2 38-41 19-20 

1535-4317-20 

630-3114-15 5 32-3518-19 6 36-45 29-3120-23 7 48-51 36-40 24-30 6 56-64 44-4 33-35 

538-4017-18 10 44-4823-24 11 51-56 31-362 -32 2 61-65 41-4236-38 10 74- 1 51-5743-50 

1537-4017-19 10 41-451922 10 44-50 29-3323-27 10 54·64 38-4329-34 7 68-76 44-5134-37 

438-4017-18 4 43-4721-23 2 35 -40 29-31 3 40-4134-35 2 50-5241-44 

1034-39 16-18 10 40-4620-23 12 41-53 32·3523-28 13 51-64 38-4328-35 10 72-80 49-5737-42 

1039-44 18-20 5 44-48 21-23 

10 42-44 21-26 10 45-4925-28 10 52-60 35-4332-37 12 63-67 46-54 39-42 6 73-81 54-6142-50 

77 32-4416-20 53 40-50 20-26 57 48-58 24 3422-31 45 56-74 34-44 30-37 33 60-86 42-58 36-

1024-2617-18 10 26-3017-20 10 24-2523-24 30-3126-29 5 

879-8510-77 10 92-11112-14 9 118-134 16-18 6 167-18232-3623-27 

2 42 12 8 48-5115-16 10 54-58 23-2518-19 6 61-67 26-3022-24 5 66-74 36-38 26-

Table 16.-Size of barnacle cyprids reared in the laboratory: SC = 

North Inlet, South Carolina, RI = Narragansett, Rhode Island; n = number measured. See Materials and Methods for diet abbreviations. 

5a. Shield with dorsal and lateral spines ......... 6 

5b. Shield without dorsal and lateral spines ...... 7 

Width Length 

(microns) 

Species Source Diet-Temp. °C n x±sd x±sd 

Balanus amphitrite SC 

SC 

Balanus ebumeus SC 

SC 

Balanus improvisus SC 

RI 

Balanus trigonus SC 

Balanus venustus SC 

RI 

Chelonibia patula SC 

Chthamalus tragilis SC 

Octolasmis muelleri SC 

TET/MON 

TET/MON 

TET/MON 

TET/MON 

TET/MON 

TET/MON 

TET/MON 

TET/MON 

TET/MON 

TET/MON 

TET/MON 

TET/MON 

20 32 239±17 

25 38 214±17 

20 12 247±08 

25 14 242±11 

25 5 267±19 

20 10 257±24 

25 7 264±19 

25 6 235±10 

20 16 243±16 

25 10 262±05 

25 25 217±22 

27 10 223±21 

4a. Abdominal process long, furcal lobes 

absent or poorly developed (Fig. 35B, 

499±l4 

477±22 

547±l6 

528±22 

551±26 

573±16 

570±27 

545±08 

572±34 

648±30 

456±25 

572±25 

34C) ...................... Octolasmis muelleri 

4b. Abdominal process short, furcal lobes 

long (Fig. 35b, 34C) .. .. . ...... . .. " nauplius SC" 

34 

6a. Dorsal shield spine long (Fig. 34E) ..... C. galeata 

6b. Dorsal shield spine short (FIg. 33E) 

.................................. B. venustus 

7a. Frontolateral horn tips directed distinctly 

forward (Fig. 35C) .................. . ...... 8 

7b. Frontolateral horn tips perpendicular to 

shield median axis or directed rearward 

(Fig.35c) ................................. 10 

8a. Larva greater than 200 /-Lm wide, circular 

shield (Fig. 34F) ..................... . C. patula 

8b. Larva less than 200/-Lm wide, shield elliptical. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9 

9a. Labrum with distinct teeth on median 

lobe (Fig. 33B) ......... B. improvisus (summer) 

9b. Labrum without distinct teeth on median 

lobe (Fig. 33A) .... ..... . .. ........ B . eburneus 

lOa. Frontolateral horns very short (Fig. 

33D) ........................... . B. subalbidus 

lOb. Frontolateral horns normal ................. 11 
v u ~lI 

X .Y A 

QQ E F 

Q H B b 

Figure 35.-Morphological features of Carolina barnacle nauplii: 

labrum of Octolasmis (A) and Lepas (a); AP and OTS of Octolasmis 

(B ) and "nauplius SC" (b); forward orientation (C) and perpendicular orientation (c) offrontolateral horns; frontolateral horns and APOTS configuration of Balanus subalbidus (0) and B. a. amphitrite 

(d ); stage IV carapace outlines of B. subalbidus (E), B. amphitrite 

(F), B. eburneus (H), and B. trigonus (G). (See naupliar keys for details.) 

11a. Larva less than 340 j.Lm wide, lateral 

shield margin somewhat straight with one 

pair of small rounded spines (Fig. 

33c) .................. ....... ... . B. amphitrite 

lIb. Larva more than 340 ,urn long, lateral 

shield margins rounded ............. , , . , .. ,. 12 

l2a. Frontolateral horns perpendicular to body 

axis or directed slightly anteriorly, lb 

median lobe with teeth (Fig. 33B) ..... , . 

.............. , ..... , ... . B. improuisus (winter) 

l2b. Frontolateral horns curved slightly posteriorly, lb median lobe without teeth (Fig. 

34H) .......... , ................... B. trigonus 

Key to Stage III Nauplii of the Carolinas 

la. Labrum unilobed .............. as in stage II key 

lb. Labrum trilobed. . . . . . . . . . . . . . . . . . . . . . . . . .. 5 

5a. Shield with paired dorsal spines ............. 6 

5b. Shield without dorsal spines ................ 7 

6a. Dorsal shield spines long, approximate 

length of fh ......................... C. galeata 

6b. Dorsal shield spines very short ....... B. uenustus 

7a. Shield wide (over 250 j.Lm) and round ... . C. patula 

7b. Shield narrow (less than 250 !Jm) ............ 8 

8a. Frontolateral horns directed perpendicularly or rearward. . . . . . . . . . . . . . . . . . . . . . . . .. 9 

8b. Frontolateral horns directed distinctly 

forward ................................... 10 

35 

9a. Frontolateral horns very short and straight, 

AP less than half the length of the DTS 

(Fig. 35D) ............ , ......... R. ubalbldu 

9b. Frontolateral horns curved rearward AP 

one-half length ofDTS (Fig. 35c) .. . B. amphitrite 

lOa. Abdominal process one-half length of 

DTS or less, fh extend straight ....... B. eburneus 

lOb. Abdominal process over one-half length 

of DTS, fh bend at tips ..................... 11 

lla. Labrum with teeth on median lobe, larvae 

less than 440 j.Lm in length ......... . B. improui u 

lIb. Labrum without teeth, larva over 440 j.Lm 

in length ........................... B. trigonus 

Key to Stages IV -V N a uplii of the Carolinas 

la. Labrum unilobed ........... as in stage II key 

lb. Labrum trilobed ......................... 5 

5a. Shield with dorsal spines .............. .... 6 

5b. Shield without dorsal spines ............... 7 

6a. Long paired dorsal shield spines, distinct 

lateral spines ........... ....... ... C. galeata 

6b. Very short paired dorsal shield spines, 

spinulose shield margins ............ R. uenustus 

7a. Shield nearly as wide as long, PS spines 

short, AnI with SPPS terminal setae .. C. patula 

7b. Shield longer than wide, AnI with PSPP 

terminal setae . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8 

8a. Frontolateral horn tips perpendicular or 

directed rearward . . . . . . . . . . . . . . . . . . . . . . . . .. 9 

8b. Frontolateral horn tips directed forward ...... 10 

9a. Frontal horns short, PS spines long, AP 

less than one-half length of DTS (Fig. 

35E) ........................... . B. subalbidus 

9b. Frontolateral horns short to moderate, PS 

spines shoot, AP one-half length of DTS 

(Fig. 35F) ........................ R. amphitrite 

lOa. Abdominal process subequal or longer 

than DTS ..... ... ............... . B. improvisu5 

lOb. Abdominal process shorter than DTS . . . . . . . .. 11 

lla. Posterior shield spines long, stage V WIth 

five median spines on AP (Fig. 35G) . B. trigon us 

lIb. Posterior shield spines moderate to short, 

stage V with three median AP spines (Fig. 

35H) . . . . . . . . . . . . . . . . . . .. . .... B. eburneu~ 

Key to Stage VI N a up Iii of the Carolinas 

la. Labrum unilobed .............. as m stage II key 

lb. Labrum trilobed. . . . . . . . . . . . . . . . . . . . . . . . . .. ;:, 

5a. Shield with two dorsal ·pine .......... C galeatQ 

5b. Shield without dorsal pine ................ 6 

6a. Abdominal proce s subequal or longer 

thanDTS ......... ...................... 7 

6b. Abdominal proce horter than DT ~ ........ . 
7a. Antennules with SPSS terminal setae .. . C. patula 

7b. Antennules with PSPP terminal setae. . . . . . .. 9 

8a. Posterior shield spines longer than fu 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. subalbidus 

8b. Posterior shield spines equal or shorter in 

length than the fu . . . . . . . . . . . . . . . . . . . . . . . . .. 10 

9a. Shield length greater than 560 ~m ..... B. trigonus 

9b. Shield length less than 560 ~m ..... . B. improvisus 

lOa. Antennae with 11 setae on exopod .... B. venustus 

lOb. Antennae with 12 setae on exopod . . . . . . . . . . .. 11 

11a. Shield length generally greater than 400 

~m, fu tip extends straight .......... B. eburneus 

11b. Shield length generally less than 400 ~m, 

fu tip bent rearward .............. . B. amphitrite 

Cyprids 

Cyprid larvae are very similar in most barnacle species. Size (Table 16) and even length to width ratios of 

the carapace (Fig. 36E, F) vary with rearing conditions 

(Lang see footnote 3). Present studies have failed to find 

reliable means to identify B. amphitrite-complex cyprids 

to species. Although Chthamalus fragilis cyprids (Fig. 

36B) tend to be smaller, even this species may be confused with cyprids of B. amphitrite. 

Octolasmis cyprids (Fig. 36C) are "bean"-shaped with 

little size difference in anterior and posterior carapace 

regions; fresh specimens have a distinct bright orange 

pigment (Lang 1976). 

Chelonibia patula cyprids (Fig. 36A) are the largest 

larvae of balanomorph species in the Carolinas (Table 

16). The large compound eye is distinctive. 

Balanus trigonus (Fig. 36D) are also large but have a 

small compound eye. The carapace is "teardrop" in 

shape with well-rounded margins. 

B 

• 

c D 

. 

@ 

E F 

Figure 36.-Cyprids of Sout h Carolina: Chelonibia patula (A); 

Chthamalus fragi/is (B); Octolasmis muelleri (C); B alanus trigonus 

(D); Balanus amphitrite reared at 30°C (E); B . amphitrite reared a t 

20°C (F). Scale = 0.1 mm. 

36 

Cyprid of other species have not been observed directly. A more thorough study of pigmentation, size 

variations, and fine carapace detail may eventually 

result in methods to identify all cyprids . 

DISCUSSION 

Based on the proposed classification of the Balanomorpha (Newman and Ross 1976), larvae from at least 

one species of each balanomorph superfamily were examined: Chthamaloida, Chthamalus; Coronulaidea, 

Chelonibia; and Balanoidea, Conopea and Balanus. Two 

lepadomorph genera, Octolasmis and Lepas, were also 

studied. As the number of cirriped larval descriptions increases, it may be possible to correlate many larval 

characteristics with adult taxonomy. At present, 

information is too sparse to undertake a detailed study, 

but certain general patterns are evident. 

As observed by many previous authors, the trilobed 

naupliar Ib IS specific to the superfamilies Coronulaidea 

and Balanoidea. These groups were originally combined 

under the family Balanidea (Pilsbry 1916) and the use of 

the term "balanid nauplii" in this study refers to larvae 

from either superfamily. A unilobed Ib occurs in larvae 

from the remaining barnacle groups-the balanomorph 

superfamily, Chthamaloida, and all known lepadomorphs and verrucomorphs. Further subdivisions of Ib 

types may be possible as more larvae are described. For 

example, Lepas and Pollicipes larvae (Table 2) have a 

broad flat-edge Ib while chthamalids have a tapered 

tongue-shaped lb. 

Five of the North Inlet species studied (Fig. 33) are 

part of the Balanus amphitrite complex. Within this 

complex of closely reared species or subspecies it is possible to derive two natural groupings and three subgroups (Henry and McLaughlin 1975). Based on statistical analysis of adult characteristics, B. amphitrite, B. 

eburneus, B. improvisus, and B. subalbidus were placed 

together in the "Amphitrite group ." Henry and 

McLaughlin considered B. amphitrite and B. improvisus 

least similar within this group with B. subalbidus and B. 

eburneus intermediate between them. A similar pattern 

exists for the nauplii of these species. Balanus eburneus 

and B. improvisus larvae are diffi cult to distinguish 

while B. subalbidus and B. amphitrite nauplii are similar but relatively distinct from the first species pair. The 

fifth member of the complex found in Nort h Inlet, B . 

venustus, was placed in a separate subgroup by Henry 

and McLaughlin. Larvae of this species, with proportionally long caudal spine, lateral spines, and dorsal 

spines, are quite distinct from other larvae of the complex, thus supporting the grouping of adults. 

Balanus venustus nauplii more closely resemble those 

of Conop ea galeata during early stages, but unlike C. 

galeata, lateral and dorsal carapace spines become 

progressively smaller at each molt and by stage VI are essentially lost. The particularly large dorsal spine of C. 

galeata larvae is unique for presently described balanid 

larvae ; however, the long AP and DTS, large fu, and 

well-developed abdominal spines are evident in other lar-
e of the subfamily Archaeobalaninae (Acasta, 

hirona, Eliminius, Solido balanus-Table 2). 

The coronulid Chelonibia was long considered a 

imative balanid but has recently been reclassified 

ewman and Ross 1976). Although most adults of this 

oup are extremely specialized obligatory commensals 

R.oss and Newman 1967), C. patula will settle on both 

ustaceans and shells; its larvae may be typical of the 

nus but perhaps, like the adult, are a less-specialized 

rm. The first and second stage nauplii of C. testu-

'naria, the only other larvae of the genus described, are 

ite similar to C. patula larvae (Pillai 1958). The sigIficance of the distinctly pigmented gut region of C. 

tula larvae is unknown. If this represents yolk cells, C. 

tula may be evolving a lecithotrophic mode of developlent. The bulky body with highly arched carapace is 

milar to the form of lecithotrophic Scalpellum scalllum larvae. 

Features other than the large globular body closely reamble those of Balanoidea larvae. Setation and setal 

pes are typical; AP spination is similar, but additional 

ines rarely seen in Balanus are present. This feature 

Iso occurs in the coronuloid Tetraclita karandei 

arande 1974b). Of particular note is the retention of 

PSS AnI terminal setal pattern in all naupliar stages. 

tennular setation tends to be extremely conservative 

11 cirriped nauplii and this variation makes C. patula 

arvae unique for balanomorphs. 

Chthamalid larvae differ in many aspects from coronuDid and balanoid larvae and perhaps more closely reemble lepadomorph larvae. All chthamalid larvae have 

ispid and feathery setae and a unilobed lb. At least 16 

tae are present on the An2 endopod of stage VI nauplii 

f all chthamalid and most lepadomorph larvae, but no 

ore than 14 setae occur in balanid larvae (Table 17). 

7hthamalus tragilis nauplii, like other described larvae 

Table 17.-Setal counts for the antennae of 

stage VI nauplii of some barnacle species, "F" 

indicates feathered setae are present. 

Number of setae 

Species exopod endopod 

Coronulaidea 

Chelonibia patula 12 14 

Tetraclita purascens 10 14 

Balanoidea 

Eliminius modestus 12 14 

Conopeagaleata 11 14 

Balanus balanus 9 11 

Balanus eburneus 12 14 

Chthamaloidea 

Chthamalus fragilis 12 18F 

C. stellatus 12 18F 

G- aestuarii 12 19F 

Octomeris angulosa 12 17F 

Chamaesipho columna 12 17F 

C. brunnea 12 16F 

Other 

Verruca stroemia 12 16F 

Pollicipes polymerus 12 16F 

Lepas fascicularis 12 16F 

Nauplius Y 12 19F 

Octolasmis muelleri 11 10 

37 

in the genus (Table 2), lack PS spines and have 10 t the 

DTS by stage VI. The nauplii of the pedunculate barnacle, Ibla cumingi, bear a striking resemblance to 

tragilis and C. stallatus (Bassindale 1936) larvae, but the 

sketchy description (Karande 1974c) of Ibla nauplii prevents a detailed comparison. 

Octolasmis muelleri and O. torrestii larvae appear 

atypical in many aspects. In general appearance the 

nauplii most closely resemble Lepas larvae and indeed, 

the poecilasmatid Octolasmis is considered to be closely 

related to the Lepadae (Newman et a1. 1969). As indicated in the figures of Lepas tascicularis nauplii (Bainbridge and Roskell 1966), Lepas, like Octolasmis, ha 

bristled setae on the AnI (a feature presently unique to 

these two groups). Octolasmis larvae, however, lack AP 

spination, have a unique tapered lb, exhibit reduced 

setal numbers on the An2 (Table 17), and have a much 

reduced Mn. The cs does not develop a posterior border 

until stage V. None of these features are shared with larvae of other barnacle species. The significance or possible advantage of these modifications in OctolasmLs larvae is unknown. The reduction of the Mn and presence of 

specialized setal types on the AnI infers a possible 

modification of the general feeding behavior described 

for balanid larvae (see Rainbow and Walker 1976). The 

swimming pattern in Octolasmis nauplii consists of a 

slow sweeping movement of the appendages as opposed 

to a much more rapid beat for balanoid nauplii. It appears likely that there are fundamental differences in 

swimming and feeding behavior. 

Nauplius SC clearly demonstrates the present limited 

knowledge of cirriped larvae. Although the most common cirriped larval type in offshore plankton samples examinpd, nauplius SC does not closely resemble any larvae of known origin (Table 2). The unilobed lb, feathered setae, and An2 setation clearly excludes it from 

coronuloid and balanoid species. The tapered lb, small 

size in later stages, and furcal structure run counter to 

known features of Lepas larvae. The lack of teeth on the 

Ib and absence i)f hispid setae also make it a doubtful 

chthamaloid species. Although the size and lb resemble 

Octolasmis larvae, the short fb and appendages do not. 

Nauplius SC thus appears to originate from one of the 

numerous lepadomorph or verrucomorph families with 

unknown larval types. If its larvae are equally predominant at other times of the year, positIve identification 

would be of interest both for larval biology and cirriped 

species distribution. 

ACKNOWLEDGMENTS 

I wish to acknowledge the Belle W. Baruch Foundation and U.S. Environmental Protection Agency (EPA 

for their support of this re earch and particularly note 

the aid of Winona Vernberg, School of Public Health, 

University of South Carolina, and Don ~1iller, EPA. 

Richard Steele supplied algae used for rearing laryae in 

Rhode Island. Martha Marcy assi ted in rearing and 

maintenance of barnacle adults and nauplii. William 

Newman, Scripps Institute of Oceanography, pro\;ded 
valuable criticism and editorial assistance. Portions of 

this paper are based on a dissertation presented to the 

faculty of the Marine Science Program, University of 

South Carolina, in partial fulfillment for the Doctor of 

Philosophy Degree. 

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