U.S. Department 

of Commerce

May 2010

NOAA Professional Paper NMFS 10

Larval development and

identification of 

the genus Triglops

(Scorpaeniformes: Cottidae)

Deborah M. Blood

Ann C. Matarese
U.S. Department

of Commerce

Gary Locke

Secretary of Commerce

National Oceanic 

and Atmospheric

Administration

Jane Lubchenco, Ph.D.

Administrator of NOAA

National Marine 

Fisheries Service

Eric C. Schwaab

Assistant Administrator 

for Fisheries

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Ann C. Matarese, Ph.D. National Marine Fisheries Service

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NMFS series. 
NOAA Professional Paper NMFS 10

Larval development and identification 

of the genus Triglops (Scorpaeniformes: Cottidae)

Deborah M. Blood

Ann C. Matarese

May 2010

U.S. Department of Commerce

Seattle, Washington
Suggested reference

Blood, Deborah M., and Ann C. Matarese. 2010. Larval development and identification of the genus Triglops (Scorpaeniformes: Cottidae). NOAA Professional 

Paper NMFS 10, 43 p.

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1

Larval development and identification 

of the genus Triglops (Scorpaeniformes: Cottidae)

Deborah M. Blood (contact author)

Ann C. Matarese

Resource Assessment and Conservation Engineering Division

Alaska Fisheries Science Center

National Marine Fisheries Service, National Oceanic and Atmospheric Administration

7600 Sand Point Way NE

Seattle, WA 98115

Email address for contact author: Debbie.Blood@noaa.gov

Abstract—Prior to Pietsch’s (1993) revision of the genus Triglops, identification 

of their larvae was difficult; six species cooccur in the eastern North Pacific Ocean 

and Bering Sea and three co-occur in the 

western North Atlantic Ocean. We examined larvae from collections of the Alaska 

Fisheries Science Center and Atlantic Reference Centre and used updated meristic 

data, pigment patterns, and morphological characters to identify larvae of Triglops

forficatus, T. macellus, T. murrayi, T. nybelini,

T. pingeli, and T. scepticus; larvae of T. metopias, T. dorothy, T. jordani, and T. xenostethus

have yet to be identified and are thus not 

included in this paper. Larval Triglops are 

characterized by a high myomere count 

(42–54), heavy dorsolateral pigmentation 

on the gut, and a pointed snout. Among 

species co-occurring in the eastern North 

Pacific Ocean, T. forficatus, T. macellus,

and T. pingeli larvae are distinguished 

from each other by meristic counts and 

presence or absence of a series of postanal 

ventral melanophores. Triglops scepticus is 

differentiated from other eastern North 

Pacific Ocean larvae by having 0–3 postanal ventral melanophores, a large eye, 

and a large body depth. Among species 

co-occurring in the western North Atlantic 

Ocean, T. murrayi and T. pingeli larvae are 

distinguished from each other by meristic 

counts (vertebrae, dorsal-fin rays, and 

anal-fin rays once formed), number of 

postanal ventral melanophores, and first 

appearance and size of head spines. Triglops nybelini is distinguished from T. murrayi and T. pingeli by a large eye, pigment 

on the lateral line and dorsal midline in 

flexion larvae, and a greater number of 

dorsal-fin rays and pectoral-fin rays once 

formed. 

Introduction 

Sculpins of the family Cottidae are 

important components of North Pacific Ocean ecosystems. Nearly 200 

species are found in the North Pacific Ocean in almost every benthic 

marine habitat from the intertidal to 

the upper continental slope (Pietsch 

and Orr, 2006). Despite such diversity 

and abundance, the systematics and 

life histories, especially of their early 

stages, are poorly known. Recent genetic studies on the higher level relationships of the family Cottidae have 

demonstrated the urgent need for 

more comprehensive morphological 

studies including ontogenetic characters (Smith and Wheeler, 2004).

The genus Triglops is recognized as 

having 10 species worldwide (Table 1; 

Pietsch, 1993; Pietsch and Orr, 2006). 

Although morphologically distinct, 

the phylogenetic relationships of this 

genus to other cottid taxa have not 

been fully resolved. Species of Triglops

are characterized in part by having a 

small head, a narrow, elongate body, 

slender caudal peduncle, long anal fin 

containing 18–32 fin rays, and scales 

below the lateral line modified to 

form discrete rows of small, serrated 

plates that lie in close-set, oblique 

dermal folds. Adults are generally 

distributed in shallow to moderately 

deep water (18–600 m) throughout 

the coldwater continental shelf or 

slope regions of the North Pacific, 

North Atlantic, and Arctic oceans.

Prior to Pietsch (1993), the genus 

was in need of revision. Identification of the larvae was possible usually 

only to the level of genus owing to a 

vertebral range (42–54) that is higher 

than in most cottids. Because much of 

the meristic data for individual species 

were unavailable, specific identification of the larvae was difficult. Species 

of Triglops for which larvae were previously described include T. pingeli, T. 

murrayi, and T. nybelini, all of which 

occur in the North Atlantic Ocean; 

however, descriptions published for 

T. pingeli were incomplete or based on 

misidentified specimens, and the description of T. nybelini was incomplete. 

Ehrenbaum (1905–1909), Dunbar 

(1947), and Rass (1949) each described and illustrated one specimen 

of Triglops pingeli (18 mm, 28 mm, and 

10 mm, respectively). Koefoed (1907) 

described a series of eight larvae as 

Triglops pingeli (10–22 mm); dorsal-fin 

ray counts of five of these larvae indicate that they probably were misidentified specimens of T. murrayi. Larvae 

of Triglops murrayi (8.4–23.4 mm) 

have been described by Khan (1972) 

and Fahay (1983, 2007); Pavlov et 

al. (1992) described both eggs and 

larvae (8.0–20.2 mm) of this species. 

Dunbar and Hildebrand (1952) presented a description and photograph 

of a 27-mm SL larva of Triglops nybelini. Two larvae from Puget Sound, 

Washington, identified as Triglops sp. 

were illustrated by Blackburn (1973); 

Richardson and Washington (1980) 
2 Professional Paper NMFS 10

Table 1

Meristic characters and distribution of the genus Triglops (Pietsch, 1993; Pietsch and Orr, 2006; Mecklenburg et al., 2002). 

Pelvic-fin ray counts are I, 3 for all species.

Fin elements

Taxon Distribution Vertebrae Dorsal Anal Pectoral 

Triglops dorothy Southern Sea of Okhotsk 45–47 X–XI, 23–25 23–25 17–19

Triglops forficatus Bering Sea, Gulf of Alaska, North Pacific Ocean 52–54 X–XI, 28–30 29–32 20–22

to Cook Inlet, AK

Triglops jordani 1 Japan and Okhotsk seas, western Bering Sea 47–49 IX–XI, 25–29 26–29 18–21

Triglops macellus Aleutian Is. and eastern Bering Sea, Gulf of Alaska 49–51 X–XII, 28–31 27–31 15–17

to Washington 

Triglops metopias Aleutian Is. and Gulf of Alaska to Auke Bay, AK 47–49 X–XI, 24–28 24–28 19–22

Triglops murrayi North Atlantic and Arctic Oceans 42–47 X–XII, 192–24 18–23 16–20

Triglops nybelini North Atlantic and Arctic Oceans 46–49 X3–XII, 24–29 24–28 20–23

Triglops pingeli North Atlantic and Arctic Oceans, North Pacific 45–51 X–XIII, 23–26 21–27 174–21 

Ocean to Puget Sound, WA 

Triglops scepticus Japan and Bering seas, Gulf of Alaska to 45–46 X–XII, 21–24 22–25 18–20

Southeast Alaska 

Triglops xenostethus5 Kuril and Commander Is., southern Bering Sea 43–46 X–XI, 22–24 22–24 15–18

and Aleutian Is.

1 According to Mecklenburg et al. (2002), specimens of T. jordani were reported near the Pribilof Islands, but records are not verified and no voucher 

specimen is available.

2 According to Andriashev (1949), the minimum number of dorsal-fin rays for T. murrayi is 18.

3 According to Andriashev (1949), the minimum number of dorsal-fin spines for T. nybelini is IX.

4 According to Andriashev (1949), the minimum number of pectoral-fin rays for T. pingeli is 16.

5 According to Mecklenburg et al. (2002), a single T. xenostethus was reported from the Pribilof Islands, but no voucher specimen is available.

described similar larvae collected in the eastern North 

Pacific Ocean, but were unable to identify them to 

species. Matarese et al. (1989) presented illustrations 

of Triglops A and Triglops B larvae (Triglops sp. in Richardson and Washington [1980]) and provided general 

characters that enabled identification. Based on the few 

meristic counts available at the time, they suggested that 

Triglops A could be T. scepticus.

Updated distributional and meristic information in 

Pietsch (1993) and Pietsch and Orr (2006) provides 

enough information to identify larvae from the eastern 

North Pacific Ocean and add to the body of knowledge 

about those larvae previously identified. Specific distributional records cited in Mecklenburg et al. (2002) 

also have helped clarify the problem by narrowing what 

species are likely to spawn in the eastern North Pacific 

Ocean. In this paper, we describe and illustrate the 

first complete series of larvae of Triglops forficatus, T. 

macellus, and T. scepticus; preflexion and flexion larvae 

are described and illustrated for T. nybelini, completing 

historical developmental series. We present a revised 

series and description of larvae of Triglops pingeli and 

T. murrayi, and describe characters which differentiate these two species in the western North Atlantic 

Ocean where they co-occur. Larvae of T. dorothy (Sea 

of Okhotsk), T. jordani (Japan and Okhotsk seas), T. 

metopias (Aleutian Islands and Gulf of Alaska), and T. 

xenostethus (Kuril, Commander, and Aleutian Islands) 

remain undescribed.

Methods and materials

Many of the larvae examined for this study were collected in Puget Sound, Washington; the northern 

Gulf of Alaska; and the Bering Sea. Ichthyoplankton 

data were obtained from surveys conducted by the 

Alaska Fisheries Science Center (AFSC) Recruitment 

Processes Program. Collection data for cruises prior 

to 1988 were found in Dunn and Rugen (19891), and 

those from 1989 to 2005 in the AFSC ichthyoplankton 

cruise database (Rugen, 20002). The University of 

Washington Fish Collection (UW) was another source 

1 Dunn, J. R., and W. C. Rugen. 1989. A catalog of Northwest and 

Alaska Fisheries Center ichthyoplankton cruises 1965–1988. AFSC 

Proc. Rep. 89-04, 87 p. AFSC, NMFS, NOAA, 7600 Sand Point Way 

NE, Seattle, WA 98115. 

2 Rugen, W. C. 2000. Alaska Fisheries Science Center Ichthyoplankton Cruise Database. Resource Assessment and Conservation Engineering Division, 7600 Sand Point Way NE, Seattle, WA 98115. 

http://access.afsc.noaa.gov/icc/openframe.cfm. [Accessed: October 2009.]
3

of specimens, including material provided by the Vancouver Public Aquarium. Most larvae were collected 

using 60-cm bongo nets and originally fixed in 5% 

buffered formalin. Larvae were later transferred to and 

stored in 70% ethanol. A detailed account of sampling 

and identification protocols is available in Matarese et 

al. (2003). 

Additional material, collected from the Bay of Fundy, 

Gulf of Maine, and western North Atlantic Ocean off 

Nova Scotia and Newfoundland, was obtained from 

the Atlantic Reference Centre (ARC) of the Huntsman 

Marine Science Centre in New Brunswick, Canada. The 

collection gear listed for some of these larvae is sawtooth 

bongo (Stephenson and Power, 1988), which is a bongo 

net that is towed in stepped intervals instead of the 

standard MARMAP (Marine Resources Monitoring, Assessment, and Prediction) oblique sampling procedure 

(Smith and Richardson, 1977).

Larvae were identified using the serial approach. This 

method uses adult characters to identify juveniles and 

progressively links them to smaller specimens through 

a continuous sequence of shared or similar features. 

For this study, characters of Triglops species described by 

Pietsch (1993), especially meristic counts, were used to 

progressively link juveniles to smaller specimens. Developmental series were illustrated using a camera lucida 

attached to a dissecting microscope. Only dark melanistic pigment is described because formalin fails to 

preserve other color pigments. The best representative 

specimen of each taxon at each stage of development 

(preflexion, flexion, and postflexion) was illustrated. 

Whereas pigmentation among specimens was variable, 

some pigment described in the taxon accounts may 

not be visible on the illustrations. Descriptions and illustrations of anatomical and morphometric features 

and other terms used herein to describe placement of 

pigment can be found in Matarese et al. (1989) and 

Moser (1996).

Measurements, taken on the left side of the fish when 

possible, were made using a calibrated digital image 

analysis system. The system consists of a video camera 

attached to a dissecting stereomicroscope or camera 

lens, a computer with a digital imaging board, and a 

video monitor. Only larvae that were not badly damaged 

during collection or preservation were measured. The 

following measurements were made on larvae: 

Standard length (SL): Snout tip to notochord tip prior 

to development of caudal fin (defined as principal 

caudal-fin rays formed); to posterior margin of hypural element in flexion and postflexion larvae. All 

body lengths in this study are standard lengths.

Snout to anus length: Distance along body midline from 

snout tip to a vertical line drawn through center of 

anal opening.

Snout to first dorsal-fin length: Distance along body 

midline from snout tip to a vertical line drawn at the 

origin of the first dorsal-fin ray.

Body depth: Vertical distance from dorsal to ventral 

body margin at the anus. 

Head length (HL): Snout tip to posterior edge of 

opercle bone.

Snout length: Snout tip to anterior margin of orbit of 

left eye.

Eye diameter: Greatest distance across the left orbit. 

This measurement can be taken horizontally, vertically, or diagonally.

Interorbital width: Distance across head between dorsal 

margins of orbit.

Pectoral-fin ray length: Length of longest fin ray of 

pectoral fin, from distal edge of pectoral-fin base to 

tip of fin ray.

Measurements of morphological features listed 

above are reported as mean percent of SL or HL 

except for standard length. Using the morphometric 

measurements, an analysis of covariance (ANCOVA) 

was performed to determine whether there were any 

significant differences among species at preflexion, 

flexion, or postflexion stages when all species were 

combined as well as within two species groups. These 

groups were composed of those species co-occurring 

in the eastern North Pacific Ocean and Bering 

Sea (Pacific species: Triglops forficatus, T. macellus, 

T. pingeli, and T. scepticus) and the western North Atlantic Ocean (Atlantic species: T. murrayi, T. nybelini, 

and T. pingeli). If the test for species*covariate (SL or 

HL) interaction (the first step of the ANCOVA) was 

not significant, the second step was to test whether SL 

or HL was significant. If not significant, the covariate 

was dropped from the model and the slope of the 

final plotted “trendline” was equal to zero; otherwise, the covariate remained in the model to test for 

species. When the overall ANCOVA test for species 

was significant (P<0.05), pairwise comparisons were 

run. In comparisons between two species affected by 

low sample size, the ANCOVA/ANOVA was followed 

by pairwise tests with a Tukey-Kramer adjustment to 

investigate if any trends had been overlooked (Sokal 

and Rohlf, 1995).

When sufficient numbers of specimens were available, selected specimens were cleared and differentially 

stained to count meristic structures (Pothoff, 1984). 

Skeletal elements were recognized as ossified upon 

initial uptake of alizarin red-S. Larval head spines were 

examined; head spine terminology follows Richardson 

and Laroche (1979).

Distribution maps were made using data from the 

AFSC ichthyoplankton database or from additional 

larvae obtained from other collections. Sample size of 
4 Professional Paper NMFS 10

some taxa was limited and may not reflect their entire 

distributional range, especially in the western North 

Atlantic Ocean.

Identification of genus 

Larvae of the genus Triglops are distinguished from 

other cottid genera by the following combination of 

characters: moderately slender body shape, obliquely 

placed mouth, angular jaw, pointed snout, and a high 

vertebral count, usually ≥45 (T. murrayi = 42–47). In addition, after fin and scale development, Triglops juveniles 

and adults may be identified by the following characters: 

a long anal fin, scales below lateral line modified to form 

discrete rows of tiny serrated plates that lie in close-set, 

oblique dermal rows, slender caudal peduncle, and a 

small head with a narrow elongate body (Pietsch and 

Orr, 2006).

Species accounts

Triglops forficatus, scissortail sculpin (Figs. 1–2)

Material examined. 28 specimens (7.7–28.0 mm SL)

examined. Bering Sea: UW 126002, 3 (12.0–19.1 mm), 

54°0.30′N, 166°21.0′W, 0–81 m depth, Tucker net, 

02 June 1986; UW 125832, 1 (15.9 mm), 53°43.0′N, 

166°53.0′W, 0–105 m depth, Tucker net, 04 June 1986; 

UW 125833, 1 (15.9 mm), 54°16.0′N, 165°47.0′W, 0–46 

m depth, Tucker net, 05 June 1986; UW 125834, 1 (8.0 

mm), 53°23.4′N, 168°26.4′W, 0–44 m depth, bongo 

net, 20 April 1993; UW 125836, 1 (9.8 mm), 57°55.3′N, 

160°07.9′W, 0–35 m depth, bongo net, 22 May 1976; 

UW 125837, 1 (8.1 mm), 53°30.0′N, 169°58.9′W, 0–530 

m depth, bongo net, 11 March 1991. Gulf of Alaska: 

UW 035569, 1 (9.0 mm), 56°59.0′N, 152°47.0′W, 0–127 

m depth, bongo net, 16 April 1987; UW 035858, 2 

(7.8–9.6 mm), 54°0.0′N, 165°05.0′W, 0–74 m depth, 

Figure 1

Distribution of all known records, including material examined here, of larvae of Triglops forficatus in the Bering Sea and 

Gulf of Alaska. Each symbol may indicate more than one capture; bathymetry line equals 200 m.
5

Figure 2

Larvae of Triglops forficatus: (A) preflexion, 7.7 mm SL (standard length), UW 157757; (B) flexion, 13.8 mm 

SL, UW 105014; (C) postflexion, 21.9 mm SL, UW 105014. Illustrations by B. Vinter, under contract to the 

Alaska Fisheries Science Center, National Marine Fisheries Service.

bongo net, 27 April 1987; UW 039511, 1 (10.8 mm), 

55°20.0′N, 156°57.0′W, 0–81 m depth, bongo net, 

14 April 1986; UW 039930, 1 (9.6 mm), 57°21.5′N, 

152°26.5′W, 0–48 m depth, bongo net, 15 February 

1979; UW 105014, 3 (13.8–21.9 mm), 58°20.0′N, 

151°28.0′W, 0–74 m depth, Tucker net, 25 May 1986; 

UW 125838, 1 (19.6 mm), 56°55.0′N, 156°19.0′W, 

0–159 m depth, Tucker net, 29 May 1986; UW 056815, 

1 (9.2 mm), 58°07.5′N, 149°45.0′W, 0–197 m depth, 

bongo net, 07 March 1981; UW 157757, 1 (7.7 mm), 

56°05.0′N, 154°45.0′W, 0–34 m depth, bongo net, 

24 April 1984; UW 125841, 1 (10.4 mm), 56°43.0′N, 

152°15.0′W, 0–60 m depth, bongo net, 01 May 1972; 

UW 062274, 1 (11.6 mm), 58°03.4′N, 154°06.8′W, 

0–104 m depth, bongo net, 08 May 1990; UW 068070, 

2 (9.2–10.3 mm), 56°53.9′N, 156°29.5′W, 0–87 m 

depth, bongo net, 13 May 1989; UW 125842, 1 (14.6 

mm), 57°28.7′N, 154°42.3′W, 0–56 m depth, bongo 

net, 01 May 1991; UW 069224, 1 (9.2 mm), 56°43.9′N, 

153°39.6′W, 0–68 m depth, Tucker net, 10 April 1978; 

UW 125843, 1 (9.6 mm), 56°44.6′N, 153°38.3′W, 0–132 

m depth, Tucker net, 10 April 1978; UW 069932, 1 

(9.2 mm), 57°08.3′N, 152°34.5′W, 0–109 m depth, 

Tucker net, 08 April 1978; UW 071583, 1 (11.7 mm), 

55°38.4′N, 156°58.5′W, 0–78 m depth, bongo net, 30 

May 1990.
6 Professional Paper NMFS 10

Occurrence. Adults of Triglops forficatus are restricted 

to the North Pacific Ocean, Sea of Okhotsk, and Bering 

Sea. They are found from the Kuril Islands and western 

Kamchatka in the Sea of Okhotsk to the Commander 

Islands in the western North Pacific Ocean, to Cape Navarin in the western Bering Sea. Reported throughout 

the Aleutian Islands, T. forficatus are also found along 

the outer shelf regions of the eastern Bering Sea, eastward into the Gulf of Alaska to Kodiak Island and Cook 

Inlet, and south to Southeast Alaska (Pietsch, 1993; 

Mecklenburg et al., 2002).

Larvae of T. forficatus are found in the Bering Sea in 

Bristol Bay, around Umnak, Unalaska, and Unimak Islands in the Aleutian chain, and eastward into the Gulf 

of Alaska to east of Kodiak Island (Fig. 1). Most are 

collected in April and May, but they are found in the 

plankton from February to June inshore in the Aleutian 

Islands and over shelf areas in the Bering Sea and Gulf 

of Alaska. 

Pigment. Twenty-eight larvae were examined to describe changes in pigmentation during development.

Triglops forficatus larvae have moderate to heavy dorsal 

head and gut pigment, and a series of 21–53 postanal 

ventral melanophores (PVM) that become embedded 

with development. In some specimens, an interrupted 

series of internal melanophores above the lateral line extending from midbody to the caudal peduncle is visible.

Preflexion larvae are heavily pigmented on the dorsal 

surface of the head from between the eyes to the nape 

(Fig. 2A). Pigment is internal at the nape and extends 

posteriorly along the dorsal midline to the third myomere. The pectoral-fin base is lightly pigmented. Heavy 

peritoneal pigment covers the dorsal surface of the gut 

and smaller external melanophores encircle the portion of the gut anterior to the anus. Between 24 and 

53 internal PVM are present; the series begins 6–12 

(usually 6–7) myomeres posterior to the anus and ends 

1–4 myomeres from the tail. Melanophores are more 

widely spaced in the anterior section of the series. A 

line of internal pigment located on the posterior half 

of the body near the dorsal margin is visible in some 

specimens; number (5–17) and spacing of this series 

is highly variable. Several melanophores are visible on 

the hypural anlage and are variable in number (2–5). 

With development (8–9 mm SL), pigment can be seen 

under the gill cover. Internal pigment develops in the 

otic area and on the lateral surface of the gut. In some 

specimens, internal pigment also appears on the ventral 

surface of the gut. Pigment is visible on the ventral caudal finfold; there may be up to 10 melanophores in the 

ventral caudal fin area (finfold and hypural anlagen).

Early flexion stage larvae (about 10–11 mm SL) develop pigment on the lower jaw and on the anterior portion of the median cartilage between the dentaries. Fine 

pigment is visible on the dorsal rim of the orbit. On the 

postanal body, 21–52 PVM begin 3–8 myomeres (usually 

5–7) posterior to the anus. This series extends to within 

3–4 myomeres from the developing hypural plate or it 

may extend onto the lower hypural area; spacing of the 

melanophores is similar to that in preflexion larvae. 

Internal pigment between the lateral line and dorsal 

margin, when visible, consists of 8–9 melanophores 

spaced irregularly on the posterior third of the body 

and ending 2–3 myomeres from the tail tip. External 

pigment can be seen near the notochord in the area of 

the caudal peduncle (Fig. 2B). Ventral caudal finfold 

pigment persists through flexion and the number and 

placement of melanophores on the base of the caudalfin rays is variable.

Late flexion larvae develop increased pigment on the 

snout, lower jaw, and gular region. Internal pigment is 

visible in the preopercular area posterior to the eye, and 

pigment on the pectoral-fin base is more prominent. 

Postanal ventral melanophores begin to move inward 

from the ventral midline in the area where the anal fin 

develops to form an incomplete row on either side of 

the ventral midline; pigment posterior to the anal fin 

remains in a single row along the ventral midline. A few 

melanophores develop on the caudal-fin base.

Pigment continues to increase in postflexion larvae on 

the upper and lower jaw (Fig. 2C). Pigment in the gular 

region increases and begins to move anteriorly toward 

the chin. Snout pigment becomes mostly embedded. 

Pigment on the gut now covers all but the anterior portion of the ventral midline, and ventral melanophores 

are smaller than those on the dorsal and lateral surfaces 

of the gut. On some specimens, two melanophores appear on each side of the dorsal midline near dorsal-fin 

soft rays 7–8. Pigment can also be seen in some specimens along and adjacent to the dorsal midline over the 

hindbrain, nape, gut, and midbody, and scattered towards the caudal fin. Internal melanophores between 

the lateral line and dorsal midline, when visible, are 

located on each of the posteriormost 13 myomeres. 

The postanal ventral pigment series has 26–33 melanophores that begin 1–10 myomeres posterior to the anus 

and continue as an incomplete row on either side of 

the ventral midline to the end of the anal fin. Pigment 

on the caudal-fin base is mostly internal and restricted 

to the lower hypural area. Upper and lower principal 

caudal-fin rays each have 3–4 melanophores at the base. 

Proportions. Notochord flexion in Triglopsforficatus begins about 9 mm SL; most larvae have completed flexion 

by 17 mm SL. Most body measurements increase throughout development (Table 2). Snout length/HL increases 

less than any body part measured, pectoral-fin length/

SL increases more than any body part measured, and 

eye diameter/HL decreases throughout development. 
7

Table 2

Proportional measurements for larvae of Triglops forficatus, T. macellus, T. murrayi, T. nybelini, T. pingeli, and T. scepticus. 

Proportions are expressed as percent of standard length (SL) except for snout length, eye diameter, and interorbital width, 

which are expressed as percent of head length (HL). Values are mean, standard deviation, and range (in parentheses). 

Length Snout

Standard to to first Inter- PectoralSpecies length anus dorsal-fin Body Head Snout Eye orbital fin

Stage (mm) length/SL length/SL depth/SL length/SL length/HL diameter/HL width/HL length/SL

Triglops forficatus

Preflexion 7.7–10.4 36.3±1.8 22.9±2.1 9.4±0.9 21.0±2.0 24.7±5.2 45.4±5.7 26.4±4.8 7.0±1.3

n=11 (33.3–39.2) (20.1–27.7) (7.8–10.4) (18.1–24.7) (15.0–35.9) (36.6–53.6) (18.0–34.5) (3.9–9.1)

Flexion 9.2–16.7 40.0±2.5 26.4±2.5 11.3±1.6 24.5±3.0 26.8±5.3 38.3±5.9 23.1±3.3 9.6±2.9

n=12 (36.8–43.9) (22.2–31.1) (9.3–13.7) (20.2–29.1) (16.9–33.4) (30.0–47.3) (18.4–29.1) (6.1–14.8)

Postflexion 15.9–21.9 42.2±1.9 28.8±1.4 13.3±0.5 27.2±2.3 27.3±2.7 32.4±2.6 25.7±3.2 18.8±1.1

n=5 (40.2–44.9) (27.0–30.6) (12.9–14.2) (24.7–30.5) (23.3–31.1) (28.2–34.3) (22.5–30.2) (17.2–20.1)

T. macellus 

Preflexion 7.3–9.6 36.7±2.4 23.4±1.2 8.5±1.0 20.5±1.5 16.4±4.6 46.0±3.7 28.9±4.8 6.6±1.1

n=8 (33.7–41.1) (21.8–25.0) (7.2–9.6) (18.3–22.9) (12.1–25.1) (40.1–50.8) (23.3–37.1) (4.7–8.0)

Flexion 9.4–14.8 44.6±2.5 28.7±2.1 13.7±2.0 27.0±3.6 26.2±3.5 37.0±5.0 26.9±4.2 12.7±4.2

n=17 (40.4–49.7) (24.2–31.6) (10.2–17.2) (20.8–32.2) (18.8–31.3) (29.5–44.8) (21.0–34.5) (5.7–21.5)

Postflexion 17.2–20.3 43.6±1.4 28.3±2.1 14.5±0.8 28.3±2.2 28.7±2.6 33.2±4.5 23.7±2.7 21.2±2.0

n=7 (42.1–46.2) (24.7–31.0) (13.7–15.4) (25.4–31.9) (24.7–32.0) (27.7–40.5) (20.3–28.2) (17.8–23.0)

T. murrayi

Preflexion 9.2–10.3 38.4±1.2 25.2±2.4 10.7±0.4 22.1±0.7 29.6±3.3 37.9±1.4 24.7±3.0 5.5±0.9

n=3 (37.2–39.7) (23.1–27.8) (10.3–11.1) (21.5–22.8) (26.2–32.8) (36.5–39.3) (21.4–27.2) (4.8–6.5)

Flexion 10.5–17.5 45.4±2.3 28.1±1.6 12.4±0.8 25.6±2.1 32.6±2.9 30.8±4.1 23.6±3.71 10.4±3.8

n=12 (41.2–49.8) (24.8–30.9) (11.1–13.5) (21.4–28.4) (24.6–37.7) (26.5–40.6) (19.2–32.0) (5.7–19.1)

Postflexion 18.7–23.4 44.1±2.2 26.7±2.1 12.7±2.2 27.1±3.2 31.4±4.2 26.8±2.1 19.9±2.5 21.3±3.52

n=4 (41.0–45.8) (24.0–29.1) (10.9–15.4) (22.4–29.8) (25.9–35.9) (24.8–29.6) (16.6–22.2) (18.3–25.1)

T. nybelini

Preflexion 8.0–10.1 36.3±1.1 22.4±0.6 9.1±0.8 20.4±1.1 23.2±7.2 47.3±2.7 35.3±1.1 6.3±1.0

n=3 (35.1–37.0) (22.0–23.0) (8.2–9.6) (19.1–21.2) (17.0–31.0) (44.2–49.3) (34.1–36.3) (5.3–7.4)

Flexion 11.5–14.4 44.9±1.6 31.3±2.6 13.1±3.0 25.4±0.1 27.0±1.8 36.9±2.5 283 9.9±3.9

n=2 (43.8–46.0) (29.5–33.1) (11.0–15.2) (25.3–25.4) (25.7–28.3) (35.2–38.7) (7.1–12.7)

T. pingeli

Preflexion 6.2–10.1 36.3±2.9 22.3±2.6 9.1±1.2 21.2±2.7 23.5±5.4 43.5±5.3 32.5±8.2 6.7±1.4

n=16 (32.4–42.5) (19.7–27.8) (7.0–10.9) (17.7–28.1) (13.4–31.6) (33.1–51.5) (19.7–48.3) (3.7–8.9)

Flexion 9.8–14.3 43.9±2.4 28.2±2.4 12.3±1.3 26.4±3.7 31.1±4.3 32.6±5.0 25.4±4.3 10.1±3.0

n=15 (40.3–48.1) (23.4–34.3) (10.2–15.5) (20.7–32.5) (22.3–37.9) (24.9–40.0) (18.9–34.1) (4.7–17.6)

Postflexion 15.3–18.1 45.5±1.8 29.3±2.0 14.7±0.7 30.9±2.0 30.4±2.7 27.0±1.9 20.8±4.2 20.4±1.8

n=6 (42.2–47.6) (27.6–33.1) (13.6–15.4) (28.2–34.3) (28.2–34.1) (24.4–29.3) (13.2–25.2) (17.7–22.4)

T. scepticus

Preflexion 9.0–9.3 39.7±4.4 24.4±1.5 10.7±2.0 23.5±0.4 25.8±4.2 46.4±4.2 29.0±3.4 7.1±0.6

n=2 (36.6–42.8) (23.4–25.4) (9.3–12.1) (23.3–23.8) (22.8–28.7) (43.4–49.4) (26.5–31.4) (6.6–7.5)

Flexion 13.6–16.7 48.9±1.6 29.9±2.1 17.5±0.7 30.4±1.3 27.2±2.6 36.9±1.4 28.8±2.3 14.2±3.4

n=4 (47.5–51.2) (28.5–33.0) (16.7–18.3) (29.1–32.0) (23.8–30.3) (35.4–38.6) (26.5–31.8) (9.2–16.6)

Postflexion 18.5–19.0 47.9±3.7 28.8±0.9 17.2±2.2 30.1±1.0 26.4±5.9 33.1±1.8 37.2±12.9 21.0±5.7 

n=2 (45.3–50.4) (28.2–29.5) (15.7–18.8) (29.4–30.8) (22.2–30.5) (31.8–34.3) (28.1–46.3) (17.0–25.0)

1 11 larvae measured.

2 3 larvae measured.

3 1 larva measured.

Interorbital width/HL decreases from preflexion larvae 

to flexion larvae, then increases in postflexion larvae.

Spination. Of the specimens available for clearing

and staining, no spines are ossified until late flexion 

(14.6 mm SL). Single parietal, nuchal, postocular, and 

posttemporal spines are present. A single row of four 

equal-sized preopercular spines lies posterior to an 

incomplete anterior row of three spines. The fourth anterior preopercular spine is ossified and the parietal and 
8 Professional Paper NMFS 10

nuchal spines are fused at the base by 18.5 mm SL. The 

supracleithral and an additional posttemporal spine are 

ossified by postflexion (20.9 mm SL). Nasal spines are 

ossified by 23.0 mm SL.

Morphological and other character comparisons.

Triglops forficatus have the highest number of vertebrae 

of all Triglops species (52–54), a high number of dorsalfin rays (28–30), the highest number of anal-fin rays 

(29–32), and a high number of pectoral-fin rays (20–22) 

(Table 1). Larvae have moderate to heavy head and gut 

pigment, a ventral midline pigment series with more 

PVM than other preflexion and flexion stage Triglops

larvae (up to 53), and the most melanophores in the 

ventral caudal-fin area (up to 10) (Table 3). 

Table 3

Summary of meristic and pigment characters useful to distinguish among known Triglops larvae. N/A=character not 

applicable, ---- = no specimens at a particular stage of development. Values in parentheses = mean±standard deviation and 

sample size.

T. forficatus T. macellus T. murrayi T. nybelini T. pingeli T. scepticus

Vertebrae 52–54 49–51 42–47 46–49 45–51 45–46

Dorsal-fin elements X–XI, 28–30 X–XII, 28–31 X–XII, 19–24 X–XII, 24–29 X–XIII, 23–26 X–XII, 21–24

Anal-fin rays 29–32 27–31 18–23 24–28 21–27 22–25

Pectoral-fin rays 20–22 15–17 16–20 20–23 17–21 18–20

Number of postanal ventral melanophores (PVM) 

preflexion 24–53 none 19–26 22–45 30–49 2–3 

(42±10.0, 9) (23±3.8, 3) (35±11.8, 3) (37±4.9, 12) (2.5±0.7, 2)

flexion 21–52 none 11–25 20–30 23–38 2

(35±10.1, 12) (20±3.6, 11) (25±7.1, 2) (32±6.4, 10) (2±0, 4)

postflexion 26–33 none 21 ---- 23–34 none

(30±3.4, 5) (21±0, 3) (27±4.8, 4)

Beginning of PVM series (number of myomeres after anus)

preflexion 6–12 N/A 6–11 6–10 6–10 24

flexion 3–8 N/A 6–14 4 4–9 20

postflexion 1–10 N/A 5 ---- 5–9 N/A

Ventrolateral pigment

preflexion no no no yes sometimes yes

flexion no no sometimes yes yes yes

postflexion no no no ---- yes no

Ventral caudal-fin pigment (number of melanophores)

preflexion 2–10 no 0–1 0–1 0–1 5–6

flexion number variable no number variable no number variable 2

postflexion 3–4 no 3–4 ---- 0–several no

Dorsal midline pigment

preflexion no no no no no no

flexion no no no yes no no

postflexion sometimes no yes (light) ---- no yes

Dorsolateral pigment

preflexion sometimes no no no no no

flexion sometimes; 8–9 no sometimes no no no

postflexion sometimes; 13 no yes (light) ---- no yes

Dorsal notochord pigment

preflexion no no no yes no no

flexion no no no yes no no

postflexion no no no ---- no no

Significant differences in morphological characters 

between Triglops forficatus and all other Triglops species 

are found in flexion stage larvae (Table 4). Larvae of 

Triglops forficatus have a significantly shorter snout to 

anus length/SL than all other larvae (Appendix 1) and 

significantly shorter snout to first dorsal-fin length/SL 

than all except larvae of T. murrayi (Table 4). Among 

those species co-occurring in the eastern North Pacific 

Ocean and Bering Sea (Pacific species—Triglops forficatus, T. macellus, T. pingeli, and T. scepticus), larvae of T. forficatus have a significantly shorter snout to anus length/

SL (Appendix 1; although this is the graph showing all 

species of Triglops, the graph for the western species was 

identical in relation to the positions of points and equation lines), shorter snout to first dorsal-fin length/SL 
9

Table 4

Summary of morphological characters useful to distinguish among all known larvae of Triglops, among known species cooccurring off western North America (Pacific species), and among known species co-occurring off eastern North America 

(Atlantic species). Entries denote if a species has a statistically significant (P≤0.05) greater or smaller value than other 

species. If a species name appears next to an entry, there is no significant difference between it and the taxon name at the 

top of the column. SL=standard length, HL=head length.

T. forficatus T. macellus T. murrayi T. nybelini T. pingeli T. scepticus

All species

Sount to anus length/SL

 preflexion

 flexion shortest greatest

 postflexion greatest (T. murrayi)

Snout to first dorsal-fin length/SL

 preflexion

 flexion shortest (T. murrayi)

 postflexion

Body depth/SL

 preflexion

 flexion greatest

 postflexion greatest (T. macellus)

Snout length/HL

 preflexion shortest (T. scepticus*)

 flexion greatest (T. pingeli)

 postflexion

Eye diameter/HL

 preflexion smallest (T. murrayi) greatest (T. nybelini)

 flexion smallest (T. murrayi) greatest

 postflexion smallest (T. murrayi)

Interorbital width/HL

 preflexion

 flexion greatest

 postflexion

Pacific species

Sount to anus length/SL

 preflexion

 flexion shortest greatest

 postflexion greatest

Snout to first dorsal-fin length/SL

 preflexion

 flexion shortest

 postflexion

Body depth/SL

 preflexion

 flexion smallest greatest

 postflexion

Snout length/HL

 preflexion shortest (T. scepticus*)

 flexion greatest

 postflexion

Eye diameter/HL

 preflexion smallest greatest

 flexion smallest greatest

 postflexion smallest

Atlantic species

Eye diameter/HL

 preflexion greatest

 flexion greatest

 postflexion

Pectoral-fin length/SL

 preflexion

 flexion greatest

 postflexion

* Due to small sample size of T. scepticus larvae, snout length of T. macellus not significantly different at P=0.05, but was at P=0.10.

Not Present

Not Present Not Present
10 Professional Paper NMFS 10

(Appendix 2), and smaller body depth/SL (Appendix 

3) than all other flexion stage larvae.

Larvae of Triglops forficatus are most similar to those 

of T. pingeli, but have higher counts for vertebrae, 

dorsal-fin rays, anal-fin rays, and pectoral-fin rays 

(Table 1). In addition, larvae of Triglops forficatus

can be differentiated from those of T. pingeli by 

having more pigment on the dorsal surface of the 

head, possible presence of dorsolateral pigment, no 

ventrolateral pigment, more pigment on the ventral 

caudal finfold during the preflexion stage, and more 

pigment on the base of the caudal-fin rays (Figs. 2 

and 12; Table 3).

Triglops macellus, roughspine sculpin (Figs. 3–4)

Material examined. 34 specimens (7.3–20.3 mm

SL) examined. Bering Sea: UW 037593, 1 (8.1 mm), 

59°40.0′N, 147°40.0′W, 0–110 m depth, bongo net, 22 

March 1988. Gulf of Alaska: UW 125844, 1 (9.3 mm), 

57°22.0′N, 151°42.0′W, 0–59 m depth, bongo net, 

06 May 1972; UW 036117, 1 (20.3 mm), 55°45.7′N, 

155°59.3′W, 0–128 m depth, bongo net, 23 May 1983; 

UW 059540, 1 (19.2 mm), 56°29.6′N, 152°55.0′W, 

0–50 m depth, bongo net, 21 May 1982; UW 059949, 

1 (19.9 mm), 55°14.1′N, 159°02.0′W, 0–189 m depth, 

bongo net, 29 May 1982; UW 137136, 2 (8.0–8.2 mm), 

57°02.8′N, 154°57.0′W, 0–100 m depth, bongo net, 

07 April 1982; UW 039989, 1 (7.3 mm), 56°33.1′N, 

154°51.1′W, 0–17 m depth, bongo net, 17 February 

1979; UW 125848, 10 (11.8–19.7 mm), 58°20.0′N, 

151°28.0′W, 0–74 m depth, Tucker net, 25 May 1986; 

UW 125845, 2 (10.3–17.2 mm), 56°40.0′N, 153°39.0′W, 

0–92 m depth, Tucker net, 27 May 1986; UW 125884, 

1 (14.8 mm), 56°55.0′N, 156°19.0′W, 0–159 m depth, 

Tucker net, 29 May 1986; UW 057199, 1 (9.3 mm), 

54°25.2′N, 161°14.0′W, 0–100 m depth, bongo net, 

26 March 1981; UW 065112, 1 (9.5 mm), 55°13.5′N, 

157°56.0′W, 0–77 m depth, bongo net, 24 April 1981; 

UW 068831, 1 (11.7 mm), 56°54.8′N, 155°42.0′W, 

Figure 3

Distribution of all known records, including material examined here, of larvae of Triglops macellus in the Bering Sea; Gulf of 

Alaska; Howe Sound, British Columbia; and Puget Sound, Washington. Each symbol may indicate more than one capture; 

bathymetry line equals 200 m.
11

Figure 4

Larvae of Triglops macellus: (A) preflexion, 8.2 mm SL (standard length), UW 137136; (B) flexion, 11.3 mm SL, UW 105048; 

(C) postflexion, 17.9 mm SL, UW 105056. Illustrations by B. Vinter.

0–197 m depth, bongo net, 24 May 1981; UW 125885, 

1 (9.6 mm), 56°56.5′N, 153°27.0′W, 0–137 m depth, 

bongo net, 15 March 1981; UW 125886, 1 (9.6 mm), 

55°47.1′N, 155°55.4′W, 0–83 m depth, bongo net, 

04 May 1992; UW 125887, 1 (9.4 mm), 57°36.8′N, 

151°48.8′W, 0–111 m depth, Tucker net, 08 April 1978; 

UW 069307, 1 (13.9 mm), 57°57.2′N, 151°47.0′W, 0–31 

m depth, Tucker net, 29 March 1978; UW 105048, 

1(11.3 mm), 56°32.9′N, 155°52.0′W, 0–108 m depth, 

Tucker net, 01 June 1989; UW 125888, 1 (9.6 mm), 

55°38.4′N, 156°58.8′W, 0–79 m depth, Tucket net, 05 

June 1989. British Columbia: UW 105046, 2 (7.3–7.5 

mm), 49°29.0′N, 123°18.0′W, depth unknown, gear 

unknown, 28 December 1984. Puget Sound: UW 

125889, 1 (13.8 mm), 48°30.0′N, 122°58.8′W, 0–1 m 

depth, dip net, 01 April 1980; UW 105056, 1 (17.9 

mm), 48°30.0′N, 122°58.8′W, 0–1 m depth, dip net, 

07 April 1994. 

Occurrence. Adults of Triglops macellus are restricted 

to the Bering Sea and North Pacific Ocean. They are 

found in the Bering Sea as far north as St. Matthew and 
12 Professional Paper NMFS 10

Nunivak islands (about 60oN), in the Aleutian Islands, 

the Gulf of Alaska to the British Columbia coast, and 

into Puget Sound, Washington (Pietsch, 1993; Mecklenburg et al., 2002). 

Larvae of Triglops macellus are found in the southern 

portion of Bristol Bay in the Bering Sea and Unimak 

Pass, eastward throughout the northern Gulf of Alaska 

to Prince William Sound. Larvae are also found farther 

south in Howe Sound, British Columbia, and Puget 

Sound, Washington (Fig. 3). Most larvae are collected 

in May, but they are found in the plankton from February to July over the shelf regions of the eastern Bering 

Sea and Gulf of Alaska and inshore in Howe Sound, 

British Columbia and Puget Sound, Washington.

Pigment. Thirty-four larvae were examined to describe changes in pigmentation during development. 

Triglops macellus is identified by heavy head and gut 

pigment and the absence of postanal pigment (Fig. 4). 

Pigment on preflexion larvae is found dorsally on 

the head from the snout to the posterior margin of the 

midbrain. Scattered and light internal pigment is present in the otic area and on the nape. A small amount 

of pigment is present on the jaw angle (Fig. 4A). In the 

abdominal region, internal pigment covers the dorsal 

and lateral surfaces of the gut; external melanophores 

form an oblique row along the anterior margin of the 

gut and cover the posterior one-third of the ventral surface of the gut. Initially, a few melanophores are present 

on the pectoral-fin base, isthmus, and the cleithral area 

under the gill cover; these areas become more heavily 

pigmented in later preflexion larvae. With development, pigment is visible on the upper jaw and in the area 

of the preopercle. Pigment on the dorsal surface of the 

head becomes heavier over the midbrain and in the otic 

and nape areas. Internal and external pigment on the 

dorsal rim of the orbit is visible in some specimens. Gut 

pigment also becomes heavier as melanophores cover 

all but the anterior half of the ventral surface of the gut.

Head pigment increases in early flexion larvae, appearing on the membrane between the upper jaw and 

snout, lateral surface of the snout, lower jaw, and along 

the median cartilage between the dentaries. More pigment is visible in the preopercular region. By about 11 

mm SL (Fig. 4B), a small patch of melanophores appears on the head near the otic region; light pigment 

appears in the opercular area by about 13.5 mm SL. 

After 14.5 mm SL, nape pigment is more difficult to 

see as it becomes more deeply embedded. Gut pigment 

becomes heavier during early flexion and the entire 

ventral surface of the gut is covered by about 11 mm 

SL. Pigment appears on the body above the pectoral-fin 

base after 12.5 mm SL. After 14.5 mm SL, melanophores 

around the anus become smaller and denser than on 

the rest of the gut. 

In postflexion larvae, pigment on the head increases 

on the upper jaw, snout, and preopercular area (Fig. 

4C). After 19.5 mm SL, fine pigment appears around 

most of the eye; the ventroposterior quadrant remains 

unpigmented. Melanophores in the gular region migrate toward the chin after about 20 mm SL. On some 

specimens a light speckling of pigment on the anterior 

myomeres dorsal to the pectoral-fin base is visible by 17.5 

mm SL; after about 19.5 mm SL this pigment becomes 

faint. After 19.5 mm SL, pectoral-fin base pigment 

spreads onto the base of the upper and lower pectoralfin rays; the central pectoral-fin rays remain unpigmented. Pectoral-fin ray pigment was not visible on the 

two largest specimens examined (19.9 and 20.3 mm SL).

Proportions. Notochord flexion in Triglops macellus begins about 9 mm SL and is complete in most larvae by 17 

mm SL. Body depth/SL, head length/SL, snout length/

HL, and pectoral-fin length/SL increase throughout 

development (Table 2). Unlike the previous three body 

proportions that increase most between preflexion and 

flexion, pectoral-fin length/SL increases more after 

flexion. Snout to anus length/SL and snout to first 

dorsal-fin length/SL increase only between preflexion 

and flexion stages. Eye diameter/HL and interorbital 

width/HL both decrease throughout development. 

Spination. Two areas of the head have ossified spines 

in an 11.8 mm SL specimen (early flexion). Two postocular spines are present; the anterior spine is smaller 

than the posterior spine. Preopercular spines form a 

double row, the anterior row having three small spines 

while the posterior row has four larger spines.

By the middle of the flexion stage, or midflexion 

(13.8 mm SL), parietal and nuchal spines have ossified 

along with an additional spine on the anterior row of 

preopercular spines. By postflexion (19.9 mm SL), the 

parietal and nuchal spines have fused at the base. The 

single nasal spine, two posttemporal spines, four small 

pterotic spines, and a supracleithral spine are ossified. 

Morphological and other character comparisons.

Although there is overlap in some meristic characters, 

larvae of Triglops macellus are distinguished by a vertebral 

count of 49–51, dorsal-fin rays 28–31, pectoral-fin rays 

15–17, heavy head and gut pigment, and a lack of postanal pigment at all stages (Table 3); this combination of 

characters is unique among the species. 

Preflexion larvae of Triglops macellus have a significantly shorter snout length/HL than all except larvae 

of T. scepticus; due to the small sample size of two T. 

scepticus larvae, snout length/HL of T. macellus was not 

significantly different at P=0.05, but it was at P=0.10 (Appendix 4). Other morphometric measurements were 

not significantly different from other species. 
13

Figure 5

Distribution of material examined of larvae of Triglops murrayi from the Bay of Fundy, Nova Scotia, and western North 

Atlantic Ocean. Each symbol may indicate more than one capture.

Triglops murrayi, moustache sculpin (Figs. 5–6)

Material examined. 18 specimens (9.2–22.6 mm SL)

examined. Northwest Atlantic: ARC 9010620, 1 (18.7 

mm), 42°00.0′N, 67°00.0′W, 0–62 m depth, bongo net, 

10 April 1985; ARC 9010648, 1 (22.6 mm), 42°40.0′N, 

66°11.0′W, 0–54 m depth, bongo net, 25 April 1984; 

ARC 9512315, 1 (21.2 mm), 46°24.0′N, 49°45.4′W, 

0–50 m depth, Tucker net, 10 June 1992; ARC 9513006, 

1 (13.6 mm), 44°30.0′N, 66°54.5′W, 32–42 m depth, 

sawtooth bongo net, 14 March 1982; ARC 9513007, 2 

(11.2–15.0 mm), 44°30.0′N, 66°54.5′W, 32–42 m depth, 

bongo net, 14 March 1982; ARC 9513008, 4 (9.6–13.7 

mm), 44°37.6′N, 66°56.2′W, 78–80 m depth, sawtooth 

bongo net, 14 March 1982; ARC 9513009, 5 (10.5–14.3 

mm), 44°04.7′N, 66°01.7′W, 27–32 m depth, sawtooth 

bongo net, 10 March 1983; ARC 9513012, 1 (17.5 

mm), 44°36.8′N, 66°55.9′W, 78–81 m depth, bongo 

net, 08 March 1981; ARC 9513024, 2 (9.2–11.6 mm), 

43°45.8′N, 60°56.9′W, 0–43 m depth, Isaacs-Kidd midwater trawl (IKMT) net, 28 January 1981. 

Occurrence. Adults of Triglops murrayi are restricted to 

the North Atlantic and Arctic oceans. They are reported 

from Hudson Bay; near Baffin Island and Ungava Bay, 

Quebec; and south to Cape Cod, Massachusetts. Eastward, they are found near Greenland, Iceland, Scotland, 

Spitsbergen, and along the shores of the White Sea 

(Pietsch, 1993).

Larvae of Triglops murrayi examined in this study were 

collected in the southern extent of their distribution. 

Larvae of T. murrayi are found in the Bay of Fundy and 

the North Atlantic Ocean south and east of Nova Scotia 

and east of Newfoundland (Fig. 5). Although larvae are 

found in the plankton from January to June, most larvae 

examined were collected in March.
14 Professional Paper NMFS 10

Figure 6

Larvae of Triglops murrayi: (A) preflexion, 9.6 mm SL (standard length), ARC 9513008; (B) flexion, 10.5 mm SL, ARC 

9513009; (C) postflexion, 22.6 mm SL, ARC 9010648. Illustrations by B. Vinter.

Pigment. Twenty-four larvae were examined to describe changes in pigmentation during development. 

Larvae of Triglops murrayi have moderate pigment on 

the head and dorsal surface of the gut. Gut pigment includes a concentration of small external melanophores 

on the lateral and ventral surfaces of the gut near the 

anus. Postanal pigment comprises a series of 11–26 PVM 

that become embedded with development and internal 

dorso- and ventrolateral pigment that is visible in some 

specimens. 

Preflexion larvae have large melanophores on the 

dorsal surface of the head with most located over the 

midbrain; 1–2 melanophores are visible over the forebrain and internal pigment is present over the hindbrain (Fig. 6A). Fine pigment is visible on the dorsal 

rim of the orbit and internal pigment is visible posterior 

to the eye in the otic region. A single melanophore is 

present under the gill cover in the cleithral region. Gut 

pigment is light to moderate with large internal melanophores on the dorsal surface of the gut and external pig-
15

ment on the dorsolateral surface of the gut. Pigment on 

the ventral surface of the gut is restricted to a few (2–4) 

small melanophores near the anus. A series of 19–26 

PVM begins 6–11 myomeres posterior to the anus and 

terminates near the last myomere. These melanophores 

are spaced approximately one per myomere along the 

ventral body margin; they may be spaced two per myomere for a short section of the series at about 70% SL. In 

most specimens, the first one or two melanophores are 

separated from the rest of the series. Postanal ventral 

melanophores are embedded and may be difficult to 

see in some specimens. A single melanophore may be 

visible on the ventral caudal finfold.

Pigment on or near the head changes little in early 

flexion larvae (about 10 mm SL), except for the addition of a few melanophores in the cleithral region and 

margin of the isthmus (Fig. 6B). Several large melanophores develop on the pectoral-fin base. Melanophores 

around the anus are smaller and finer than those on 

the dorsal surface of the gut. Postanal ventral melanophores in flexion larvae number 11–25 and begin 6–14 

myomeres posterior to the anus. Pigment extends to the 

last 1–2 myomeres. In some specimens internal pigment 

on the postanal body appears at this stage; a short row 

of dorsolateral melanophores, extending from 50% SL 

to about 75% SL, is visible in addition to several ventrolateral melanophores located just above the PVM beginning at about the middle of the postanal body. Also, a 

single embedded melanophore is visible in the hypaxial 

region of the last myomere and 1–2 melanophores are 

visible on the caudal-fin base where the upper and lower 

hypural plates meet.

During flexion (10.0–17.6 mm SL), external and 

internal pigment on the dorsal surface of the head increases. Pigment on the median cartilage between the 

dentaries is visible in the largest flexion larva (17.6 mm 

SL). A few melanophores develop in the preopercular 

region, and pigment in the cleithral region and margin 

of the isthmus becomes heavier. Melanophores appear 

on the caudal-fin rays near both of the developing upper 

and lower hypurals and on the ventral caudal finfold 

directly below the hypural; one internal melanophore 

is visible on the caudal peduncle below the notochord. 

Postflexion larvae (>18 mm SL) continue to develop 

more pigment on the head (Fig. 6C). Pigment appears 

on the lateral surface of the snout, upper and lower jaw, 

and posterior rim of the orbit. More pigment covers the 

preopercular region (both internal and external), gular 

region, isthmus, cleithral region, and pectoral-fin base. 

Large internal melanophores cover the dorsolateral 

surfaces of the gut. 

Postanal ventral pigment is difficult to see in some 

postflexion specimens. The number of PVM (21) is 

similar to that in flexion larvae, but spacing becomes 

irregular. In larger specimens, only those PVM between the end of the anal fin and beginning of the 

secondary caudal-fin rays are visible. A light speckling 

of small melanophores can be seen on the membrane 

between the upper jaw and snout, nape, on the body 

over the gut, along the midline at the base of the dorsal-fin spines and rays, on the dorsolateral body at 50% 

and 75% SL, and on the caudal peduncle. Caudal-fin 

pigment is restricted to the base of the lower primary 

caudal-fin rays.

Proportions. Notochord flexion in larvae of Triglops

murrayi begins after 10 mm SL and is complete by 18 

mm SL. Body depth/SL, head length/SL, and pectoralfin length/SL increase throughout development (Table 

2). Unlike body depth/SL and head length/SL, which 

increase minimally after flexion (2–6% increase), a 

large increase in pectoral-fin length/SL occurs after 

flexion (105%). Snout to anus length/SL, snout to first 

dorsal-fin length/SL, and snout length/HL increase 

from preflexion to flexion larvae and decrease in postflexion. Eye diameter/HL and interorbital width/HL 

both decrease throughout development.

Spination. Single parietal and nuchal spines, four

posterior preopercular spines, and two small postocular 

spines are ossified by 14.3 mm SL.

Morphological and other character comparisons.

Meristic counts for the three species found in the western North Atlantic Ocean (Triglops murrayi, T. nybelini, 

and T. pingeli) overlap to a greater degree than those 

for species in the North Pacific Ocean and Bering Sea. 

Triglops murrayi have fewer anal-fin rays than T. nybelini

and fewer dorsal-fin rays with minimal overlap. The low 

end of the range for dorsal- and anal-fin rays for T. murrayi is lower than for T. pingeli, but counts do overlap at 

the top of the range (D:23–24, A:21–23; Pietsch, 1993). 

Triglops murrayi usually has fewer PVM than T. pingeli at 

all stages of development and usually has fewer PVM 

than T. nybelini during preflexion stage (Table 3). In 

addition, T. murrayi has a short line of dorsolateral pigment during flexion stage, and large melanophores on 

the pectoral-fin base. 

Morphological comparisons of larvae of Triglops murrayi with all species resulted in a significant difference 

for only one measurement: flexion larvae of T. murrayi

have a significantly greater snout length/HL than all 

except larvae of T. pingeli. Larvae of T. murrayi are most 

similar to T. pingeli and they may be difficult to distinguish from each other. Preflexion and early flexion 

larvae of T. murrayi have large melanophores on the pectoral-fin base, whereas similar stages of T. pingeli have no 

pigment or only small melanophores in that area. Also, 

flexion larvae of T. murrayi have a significantly shorter 

pectoral-fin length/SL than T. pingeli (Appendix 5). 
16 Professional Paper NMFS 10

Triglops nybelini, bigeye sculpin (Figs. 7–9)

Material examined. Five specimens (8.0–14.4 mm SL) 

examined. Northwest Atlantic: ARC 9010624, 1 (11.5 

mm), 47°00.0′N, 44°30.0′W, 0–110 m depth, bongo net, 

11 April 1980; ARC 9513011, 1 (8.6 mm), 43°31.4′N, 

66°18.5′W, 75–79 m depth, bongo net, 05 March 1981; 

ARC 9010634, 1 (14.4 mm), 47°00.0′N, 45°00.0′W, 

0–148 m depth, bongo net, 06 May 1981; ARC 9513001, 

1 (8.0 mm), 43°56.5′N, 66°24.9′W, 0–57 m depth, sawtooth bongo net, 13 March 1982; ARC 9010623, 1 (10.1 

mm), 47°00.0′N, 45°00.0′W, 0–140 m depth, bongo net, 

13 March 1983.

Occurrence. Adults of Triglops nybelini are found in 

the North Atlantic Ocean and are nearly circumpolar 

in the Arctic Ocean. They are found in the Beaufort 

Sea; east to Baffin Island and Ungava Bay, Quebec; 

off Labrador and the west coast of Greenland; to 

Figure 7

Distribution of material examined of larvae of Triglops nybelini from the Gulf of Maine and western North Atlantic Ocean. 

Each symbol may indicate more than one capture.

Spitsbergen and the Barents, Kara, and Laptev seas 

(Pietsch, 1993).

Larvae of Triglops nybelini examined in this study were 

collected farther south than their reported adult distribution. Triglops nybelini larvae are uncommon in collections; specimens used in this study were found in the 

Gulf of Maine and in the North Atlantic Ocean east of 

Newfoundland (Fig. 7) and were collected from March 

to May.

Pigment. Five larvae (preflexion and flexion) were 

available to examine for changes in pigmentation during 

development. Larvae of Triglops nybelini have moderate 

pigment on the head and moderate to heavy pigment 

on the dorsal surface of the gut. Postanal pigment comprises a series of 20–45 PVM that become embedded with 

development, internal dorsal notochord pigment, internal ventrolateral pigment above the PVM, and dorsal 

midline pigment that is first visible in flexion specimens. 
17

Figure 8

Larvae of Triglops nybelini: (A) preflexion, 8.6 mm SL (standard length), ARC 9513011; (B) preflexion, 

10.1 mm SL, ARC 9010623; (C) flexion, 11.5 mm SL, ARC 9010624, (D) flexion, 14.4 mm SL, ARC 

9010634. Illustrations by B. Vinter.

Head pigment in early preflexion larvae (8.0 mm 

SL) is moderate. Large external melanophores are on 

the dorsal surface of the head over the forebrain and 

midbrain and small internal melanophores are visible 

on the midbrain. A large internal melanophore is visible behind the eye in the otic area and a single external melanophore is present on the nape. Pigment on 

the gut is moderate and restricted to the dorsolateral 

surface. Postanal ventral melanophores are present 

starting at nine myomeres posterior to the anus; there 

are 45 PVM, anteriorly spaced one spot per myomere. 

At 50% SL, spacing changes to one or two per myomere 
18 Professional Paper NMFS 10

Figure 9

Photograph of Triglops nybelini, 27 mm SL (standard length), collected by plankton net at 30 m depth in Ungava Bay, 

Quebec, Canada (Dunbar and Hildebrand, 1952 - reverse image of the original).

and the series terminates near the last myomere. A few 

melanophores are present on the ventral caudal finfold 

in some larvae.

With development, more pigment is visible on the 

nape and pigment appears in the cleithral area (Fig. 

8A). Pigment covers the upper half of the gut and small 

melanophores are present on the ventral surface of the 

gut near the anus. Internal dash-like pigment is visible 

above the notochord starting at 50% SL and terminating at 90% SL. Beginning six myomeres posterior to 

the anus, 38 PVM are spaced one per myomere along 

their entire length. Postanal ventral melanophores 

extend onto the ventral caudal margin beyond the last 

myomere, and there is one melanophore on the ventral 

caudal finfold.

Head pigment in the largest preflexion larva covers 

the entire dorsal surface of the head over the forebrain 

and midbrain (Fig. 8B). Nape pigment becomes embedded and is more difficult to see. Two pigment spots 

are present on the pectoral-fin base. Pigment on the 

dorsolateral surface of the gut is heavy. Internal pigment 

above the notochord is visible, starts at approximately 

50% SL, and terminates at the next to last myomere; 

these melanophores are more widely spaced anteriorly 

and more closely spaced posteriorly. Postanal ventral 

melanophores (22) begin 10 myomeres posterior to the 

anus. Those PVM located on the posterior myomeres 

and extending onto the ventral caudal margin and finfold appear to be darker than other PVM. Additional internal pigment located just above the PVM begins at approximately 50% SL and ends at approximately 90% SL.

The only additional anterior pigment visible in early 

flexion is located on the isthmus near the jaw angle and 

therefore is not visible except when viewed ventrally. 

Dorsal midline pigment has developed, beginning at 

about 50% SL and terminating at 75% SL (Fig. 8C). Melanophores are spaced about one per myomere and are 

irregular in size. Internal pigment above the notochord 

extends further anteriorly, starting about two myomeres 

posterior to the anus. Beginning four myomeres posterior to the anus are 30 PVM. These melanophores are 

dash-like and located close together; at 70% SL they 

appear to be a solid line. Multiple ventrolateral melanophores are present anterior to the developing caudal fin 

and there is one mediolateral spot located at 75% SL.

More areas of the head are pigmented in midflexion 

(Fig. 8D). Light pigment is visible on the membrane 

between the upper jaw and snout, snout (internal), 

dorsal rim of the orbit, chin, and the ventral edge of the 

dentary anterior to the jaw angle. A light speckling of 

pigment on the preopercular area behind the eye and 

additional pigment on the isthmus is present. Dorsolateral gut pigment extends over most of the gut wall and 

no pigment is present on the ventral surface of the gut. 

Dorsal midline pigment begins just posterior to the 

first dorsal-fin ray and ends about five myomeres anterior to the developing caudal fin. The melanophores 

are spaced closely together, forming a solid line until 

the last dorsal-fin ray, at which point they are constricted 

and separate. Internal pigment above the notochord 

begins at about 30% SL and ends near the last myomere 

anterior to the caudal fin. 

Postanal ventral melanophores (20) begin four myomeres posterior to the anus and terminate about four 

myomeres anterior to the developing lower hypural 

plate. The series, which is becoming embedded, is 

spaced one melanophore per myomere to about 60% 

SL and skips three myomeres. At about 65% SL, PVM 
19

are dash-like and appear as a solid line at 75% SL when 

viewed ventrally; when viewed laterally, melanophores 

look like a number of dashes until 80–90% SL where 

they appear as very small spots. More internal pigment 

above the PVM is present near the caudal peduncle.

Internal pigment is present on the developing lower 

hypural plate; external pigment is present near the 

distal margin at the point where the upper and lower 

hypural plates meet. Caudal-fin ray pigment is restricted 

to a few melanophores on the upper caudal-fin rays near 

the caudal margin.

Proportions. Notochord flexion in larvae of Triglops

nybelini begins between 10.0 and 11.5 mm SL; the largest 

larva examined (14.4 mm SL) was in late flexion stage. 

All proportions except for eye diameter/HL and interorbital width/HL increase from preflexion to flexion 

stage (Table 2). The greatest increases in morphometric 

measurements between preflexion and flexion stages 

are in snout to first dorsal-fin length/SL (39.7%), body 

depth/SL (43.9%), and pectoral-fin length/SL (57.1%). 

Spination. There were too few specimens to determine ossification of spines through clearing and staining. A single row of three preopercular spines was present on the largest larva (14.4 mm SL), in addition to 

single parietal, nuchal, posttemporal, and supracleithral 

spines. Postocular spines were not visible.

Morphological and other character comparisons.

Most meristic counts for Triglops nybelini overlap those for 

T. murrayi and T. pingeli, the other species co-occurring 

in the western North Atlantic Ocean. Triglops nybelini has 

more anal-fin rays than T. murrayi; soft dorsal-fin and 

pectoral-fin ray counts are also higher with minimal overlap (Pietsch, 1993). Although there is some overlap, T. 

nybelini usually has a higher number of anal-fin rays, soft 

dorsal-fin rays, and pectoral-fin rays than T. pingeli (Pietsch, 1993). In addition, internal ventrolateral pigment 

above the PVM on preflexion larvae and internal dorsal 

notochord pigment set T. nybelini apart. Flexion larvae of 

T. nybelini have pigment along the dorsal midline at the 

base of the dorsal-fin rays. As shown in the photograph of 

a 27-mm SL postflexion larva collected from Ungava Bay 

by Dunbar and Hildebrand (1952) (Fig. 9), this dorsal 

midline pigment becomes heavier with development.

Prior to the development of the full complement of 

fin rays, the eye diameter/HL of pre- and early flexion 

larvae of T. nybelini is significantly larger than those of 

its Atlantic congeners (Appendices 6–7).

Triglops pingeli, ribbed sculpin (Figs. 10–12)

Material examined. 45 specimens (6.1–28.5 mm SL)

examined. Northwest Atlantic: ARC 9010640, 1 (7.4 

mm), 41°41.6′N, 66°03.1′W, 0–93 m depth, IsaacsKidd midwater trawl (IKMT) net, 12 January 1982; 

ARC 9010662, 1 (10.1 mm), 43°45.0′N, 66°25.0′W, 

0–126 m depth, bongo net, 03 March 1984; ARC 

9010669, 1 (7.5 mm), 44°21.0′N, 63°37.0′W, 97–99 m 

depth, IKMT, 23 January 1979; ARC 9010700, 1 (7.1 

mm), 43°03.4′N, 64°02.1′W, 0–90 m depth, IKMT, 26 

January 1982; ARC 9010703, 1 (6.2 mm), 42°06.4′N, 

67°01.8′W, 0–56 m depth, IKMT, 13 January 1982; 

ARC 9513004, 1 (8.3 mm), 44°05.4′N, 66°16.1′W, 

27–32 m depth, sawtooth bongo net, 14 March 1982; 

ARC 9513013, 1 (8.5 mm), 43°30.6′N, 66°20.5′W, 

0–95 m depth, bongo net, 10 February 1981; ARC 

9513016, 1 (7.7 mm), 44°58.0′N, 61°20.0′W, depth 

unknown, IKMT, 16 February 1977; ARC 9513026, 

1 (6.8 mm), 45°01.0′N, 57°50.3′W, 0 m depth, sawtooth bongo net, 23 January 1981; ARC 9513027, 

1 (6.7 mm), 41°13.0′N, 60°12.4′W, 0 m depth, sawtooth bongo net, 28 January 1981; ARC 9513028, 

1 (9.0 mm), 43°08.9′N, 65°53.7′W, 0 m depth, sawtooth bongo net, 10 February 1981; ARC 9010658, 

2 (8.0–10.8 mm), 41°46.0′N, 66°39.0′W, 0–59 m 

depth, bongo net, 17 February 1985; ARC 9513006, 

1 (10.0 mm), 44°30.0′N, 66°54.5′W, 32–42 m depth, 

sawtooth bongo net, 14 March 1982; ARC 9513008, 

2 (10.2–10.7 mm), 44°37.6′N, 66°56.2′W, 78–80 m 

depth, sawtooth bongo net, 14 March 1982; ARC 

9513009, 2 (10.9–12.5 mm), 44°04.7′N, 66°15.7′W, 

27–32 m depth, sawtooth bongo net, 10 March 1983; 

ARC 9513024, 3 (8.0–9.8 mm), 43°45.8′N, 60°56.9′W, 

0–43 m depth, IKMT, 28 January 1981. Beaufort Sea: 

ARC 9010608, 1 (28.5 mm), 69°39.0′N, 125°35.0′W, 

depth unknown, gear unknown, 01 August 1963. 

Bering Sea: UW 125993, 1 (16.6 mm), 53°57.0′N, 

166°37.0′W, 0–2 m depth, Tucker net, 04 June 1986; 

UW 125994, 1 (18.2 mm), 54°15.8′N, 165°49.6′W, 

0–69 m depth, bongo net, 16 April 1993; UW 125995, 

1 (14.3 mm), 55°16.9′N, 163°20.3′W, 0–34 m depth, 

bongo net, 20 May 1976; UW 037858, 1 (12.5 mm), 

54°45.0′N, 164°55.0′W, 0–55 m depth, bongo net, 11 

April 1988. Gulf of Alaska: UW 052327, 1 (9.5 mm), 

57°11.2′N, 154°49.6′W, 0–75 m depth, bongo net, 14 

April 1989; UW 105068, 2 (16.4–17.1 mm), 55°21.0′N, 

159°46.0′W, 0–74 m depth, Tucker net, 30 May 1986; 

UW 125996, 1 (11.8 mm), 56°30.0′N, 155°14.0′W, 

0–23 m depth, bongo net, 18 March 1981; UW 

125997, 1 (16.3 mm), 57°22.0′N, 151°42.0′W, 0–59 m 

depth, bongo net, 06 May 1972; UW 125998, 1 (15.3 

mm), 57°40.7′N, 152°07.4′W, 0–146 m depth, IKMT, 

07 April 1978; UW 032200, 1 (12.1 mm), 57°16.0′N, 

152°55.0′W, 0–90 m depth, Tucker net, 05 April 1978; 

UW 032202, 1 (12.9 mm), 57°16.0′N, 152°55.0′W, 

0–50 m depth, Tucker net, 14 April 1978; UW 032203, 

1 (9.8 mm), 58°10.0′N, 152°14.0′W, 0–90 m depth, 

Tucker net, 21 April 1978; UW 032204, 1 (11.2 mm), 
20 Professional Paper NMFS 10

Figure 10

Distribution of all known records, including material examined here, of larvae of Pacific Triglops pingeli in the Beaufort 

Sea; Bering Sea; Gulf of Alaska; and Howe Sound, British Columbia. Each symbol may indicate more than one capture; 

bathymetry line equals 200 m.

57°16.0′N, 152°55.0′W, 0–100 m depth, Tucker net, 

15 March 1979; UW 032205, 1 (10.8 mm), 57°16.0′N, 

152°55.0′W, 0–30 m depth, Tucker net, 15 March 1979; 

UW 032206, 1 (8.9 mm), 58°10.0′N, 152°14.0′W, 0–10 

m depth, Tucker net, 06 March 1979. British Columbia: UW 125835, 1 (6.9 mm), 49°29.0′N, 123°18.0′W, 

depth unknown, gear unknown, 28 December 1984; 

UW 125846, 1 (7.1 mm), 49°29.0′N, 123°18.0′W, 

depth unknown, gear unknown, 28 December 1984; 

UW 105065, 3 (6.1–6.5 mm), 49°29.0′N, 123°18.0′W, 

depth unknown, gear unknown, 09 February 1985; 

UW 125992, 2 (6.4–6.5 mm), 49°29.0′N, 123°18.0′W, 

depth unknown, gear unknown, 20 March 1987.

Occurrence. Triglops pingeli is the most wide-ranging 

species of the genus, found throughout coastal waters 

of the Arctic, North Pacific, and Atlantic oceans. Adults 

have been reported in the Sea of Japan, Sea of Okhotsk, 

Bering Sea, eastern Aleutian Islands, Gulf of Alaska, 

and south to Puget Sound, Washington. Northward, 

they are found in the Chukchi and Beaufort seas; 

eastward to the Queen Elizabeth Islands, Hudson Bay, 

Baffin Island; south to Cape Cod, Massachusetts; to 

Greenland and Spitsbergen, and the Barents, Kara, and 

Laptev seas (Pietsch, 1993; Mecklenburg et al., 2002).

Of the Pacific species of Triglops larvae, T. pingeli are 

the most widespread. They are found from the Beaufort 

Sea; Pribilof Islands; west of Unimak Pass eastward to 

around Kodiak Island; and to Howe Sound on the east 

side of Vancouver Island, B.C. (Fig. 10). They are collected from January to September.

Compared with other species of the Atlantic group, 

larvae of T. pingeli are common and found in eastern 

Hudson Bay, the Atlantic Ocean east of Cape Cod, Gulf 
21

Figure 11

Distribution of material examined of larvae of Atlantic Triglops pingeli from Hudson Bay and Gulf of St. Lawrence, Quebec; 

Gulf of Maine, Bay of Fundy, Nova Scotia; and western North Atlantic Ocean. Each symbol may indicate more than one 

capture.

of Maine and northward into the Bay of Fundy, east of 

Nova Scotia and into the Gulf of St. Lawrence, and to 

the east off Newfoundland (Fig. 11). Larvae are collected from January to March.

Pigment. Forty-five larvae were examined to describe changes in pigmentation during development. 

Larvae of Triglops pingeli have moderate head and gut 

pigment. Gut pigment includes large internal dorsal 

melanophores and a concentration of small external 

melanophores on the lateral and ventral surfaces of 

the gut near the anus. Postanal pigment is composed 

of a series of PVM (yolk-sac larvae, 60–85; preflexionpostflexion larvae, 23–49) that decrease in number 

and become embedded with development.

Head pigment in yolk-sac larvae is light and is located over the midbrain and nape (Fig. 12A). Gut pigment is light with internal melanophores on the midlateral and dorsal surface of the gut; pigment on the 

ventral surface of the gut is restricted to the anterior 

margin of the gut and anus. A series of 60–85 PVM 

begins 6–7 myomeres posterior to the anus, spaced 

2–3 per myomere; an additional 5–6 melanophores 

extend onto the ventral margin of the notochord.

Head pigment in preflexion larvae is moderate; most 

is located over the midbrain and nape with 1–2 melanophores over the forebrain (Fig. 12B). Fine pigment is visible on the dorsal rim of the orbit and internal pigment 

is visible in the otic region on some specimens. A few 

melanophores are present on the cleithral region under 

the gill cover. Gut pigment is moderate with internal melanophores on the dorsal surface of the gut and external 

pigment extending to the mid-lateral surface. Pigment 

on the ventral surface of the gut is restricted to its ante-
22 Professional Paper NMFS 10

Figure 12

Larvae of Triglops pingeli: (A) yolk-sac, 6.5 mm SL (standard length), UW 105065; (B) preflexion, 8.5 mm SL, ARC 9513013; 

(C) preflexion, 9.5 mm SL, UW 052327; (D) flexion, 12.5 mm SL, UW 037858; (E) postflexion, 17.1 mm SL, UW 105068. 

Illustrations by B. Vinter.
23

rior margin and a few (2–4) small melanophores near 

the anus. A series of 30–49 PVM begins 6–10 myomeres 

posterior to the anus and terminates at the last myomere. 

These melanophores are spaced approximately one per 

myomere along the anterior half of the series and 1–2 per 

myomere along the posterior half. This series is embedded and is at times difficult to see. Additional internal 

postanal pigment is visible in some specimens, appearing 

as an irregular row directly above the PVM. Pigment in 

the caudal area consists of 1–2 melanophores near the 

ventral caudal margin and a single melanophore on the 

ventral caudal finfold in some specimens.

Head pigment increases in late preflexion larvae. 

Melanophores appear dorsally on the snout, in front 

of the eye, and on the preopercular region posterior 

to the eye (Fig. 12C). Light pigment is visible on the 

chin and on the lower jaw near the jaw angle. Nape 

pigment becomes embedded and difficult to see. Late 

preflexion larvae have fewer PVM than early preflexion 

larvae (Fig. 12B).

Pigment is visible in some flexion larvae on the median cartilage between the dentaries. A few melanophores 

develop on the isthmus, pectoral-fin base, and cleithral 

area (Fig. 12D). Melanophores around the anus are 

smaller and finer than those on the dorsal surface of the 

gut. A series of 23–38 PVM in flexion larvae begins 4–9 

myomeres posterior to the anus. Melanophores in the 

anterior half of the series are more widely and irregularly spaced, and more difficult to see than are those in 

the posterior half. Pigment extends to the last 1–2 myomeres; additional pigment (1–2 melanophores) is visible 

on the ventral margin of the hypural plate and ventral 

caudal finfold. Pigment may be visible on the caudal-fin 

base and bases of the developing caudal-fin rays.

Although the degree of pigmentation may vary greatly 

among specimens, postflexion larvae have less pigment 

on the crown, developing more pigment on other areas 

of the head (Fig. 12E). The preopercular region (with 

both internal and external melanophores), sides of the 

snout, lower jaw, and gular region are more heavily pigmented. Additional pigment appears on the anterior and 

posterior rims of the orbit, isthmus, in the cleithral region 

under the gill cover, and on the pectoral-fin base. Large 

internal melanophores cover most of the dorsal and lateral surfaces of the gut, and the ventral surface of the gut 

develops additional fine external pigment anterior to the 

anus. Postanal ventral pigment, beginning 5–9 myomeres 

posterior to the anus, is more difficult to see in some 

specimens, especially in the anterior section of the series. 

The number of PVM (23–34) and their spacing is similar 

to those in flexion larvae; however, pigment at the end of 

the series is slightly above the ventral midline. Pigment 

on the caudal-fin base is located below and sometimes 

adjacent to the notochord. Caudal-fin ray pigment, when 

present, is generally restricted to the lower half of the fin.

Proportions. Notochord flexion in larvae of Triglops

pingeli begins about 9.8 mm SL and is complete by 

about 15 mm SL. Snout to anus length/SL, snout to 

first dorsal length/SL, and head length/SL increase at 

similar rates with development (Table 2). Body depth/

SL and pectoral-fin length/SL also increase throughout 

development, but at much greater rates. Snout length/

HL increases mostly from preflexion to flexion larvae. 

Eye diameter/HL and interorbital width/HL decrease 

throughout development.

Spination. Spines are ossified by early flexion (9.8

mm SL). Parietal, nuchal, and posttemporal spines are 

single; one or two postocular spines are present, with 

most of our specimens possessing two spines. Preopercular spines form a double row with three spines in the 

anterior row and four spines in the posterior row.

In the postflexion specimen examined (16.6 mm SL), 

the parietal and nuchal spines are fused. Additional 

spines include a second posttemporal spine fused with 

the first, a fourth spine on the anterior preopercular 

spine row, and a supracleithral spine. 

Head spines of Pacific larvae of T. pingeli were visible 

at an earlier stage of development than for Atlantic 

larvae. Spines were not visible in Atlantic T. pingeli until 

late flexion (>13 mm SL).

Morphological and other character comparisons.

Among species occurring in the North Pacific Ocean

and Bering Sea, larvae of Triglops pingeli are most similar to T. forficatus, but differ in most meristic counts: 

45–51 (vs. 52–54) vertebrae, 23–26 (vs. 28–30) dorsalfin rays, 21–27 (vs. 29–32) anal-fin rays, and 17–21 (vs. 

20–22) pectoral-fin rays. In addition, larvae of T. pingeli

can be differentiated from those of T. forficatus by having less pigment on the dorsal surface of the head, a 

concentration of very small external melanophores 

on the lateral and ventral surfaces of the gut near the 

anus (pigment finer than similar pigment on T. forficatus), little or no pigment on the ventral caudal finfold 

and base of the caudal-fin rays, the earlier appearance 

of head spines (late preflexion), and larger head 

spines throughout flexion and postflexion. Among 

species occurring in the North Atlantic Ocean, characters that distinguish larvae of Triglops pingeli from 

T. murrayi and T. nybelini include a generally higher 

number of PVMs at all stages of development (23–49, 

Table 3) and larger head spines through late flexion 

and postflexion.

Morphological comparisons of larvae of Triglops pingeli with all species resulted in significant differences for 

some measurements. Except for T. murrayi, preflexion 

Triglops pingeli had a significantly smaller eye diameter/

HL, flexion T. pingeli had a significantly smaller eye diameter/HL, and postflexion T. pingeli had a significantly 
24 Professional Paper NMFS 10

smaller eye diameter/HL (because of small sample size 

in T. murrayi, head length/SL was not significant for the 

ANCOVA at 5%, but was close, so an ANOVA was run 

without head length/SL as a covariate) (Table 4).

Among the Pacific group of species, preflexion larvae of Triglops pingeli had a significantly smaller eye 

diameter/HL (Appendix 8), flexion T. pingeli had a significantly greater snout length/HL (Appendix 9) and 

significantly smaller eye diameter/HL (Appendix 10), 

and postflexion T. pingeli had a significantly smaller 

eye diameter/HL than other larvae (Appendix 11). 

Among the Atlantic group of species, flexion T. pingeli 

had a significantly greater pectoral-fin length/SL than 

T. murrayi and T. nybelini (Appendix 5).

Triglops scepticus, spectacled sculpin 

(Figs. 13–14)

Material examined. Eight specimens (9.0–19.0 mm

SL) examined. Bering Sea: UW 125999, 1 (13.6 mm), 

Figure 13

Distribution of material examined of larvae of Triglops scepticus in the Bering Sea and Gulf of Alaska. Each symbol may 

indicate more than one capture; bathymetry line equals 200 m.

53°43.0′N, 166°53.0′W, 0–105 m depth, Tucker net, 04 

June 1986; UW 105076, 3 (13.6–18.5 mm), 54°18.0′N, 

166°21.0′W, 0–81 m depth, Tucker net, 02 June 1986. 

Gulf of Alaska: UW 059622, 1 (9.0 mm), 56°10.0′N, 

154°50.0′W, 0–60 m depth, bongo net, 22 May 1982; 

UW 050998, 1 (9.3 mm), 57°51.7′N, 154°53.7′W, 0–276 

m depth, bongo net, 07 April 1986; UW 126000, 1 (16.7 

mm), 55°13.1′N, 156°49.2′W, 0–99 m depth, bongo 

net, 26 May 1996; UW 126001, 1 (19.0 mm), 54°34.6′N, 

160°23.1′W, 0–101 m depth, bongo net, 24 May 2005.

Occurrence. Adults of Triglops scepticus are restricted 

to waters in and adjacent to the North Pacific Ocean 

and Bering Sea. Adults are found from the southern 

Sea of Japan and Tatarskiy Strait to Navarin Canyon in 

the western Bering Sea, outer shelf and slope regions 

of the eastern Bering Sea, throughout the Commander 

and Aleutian Islands, east to Kodiak Island in the Gulf 

of Alaska, and southward to southeast Alaska (Pietsch, 

1993; Mecklenburg et al., 2002).
25

Figure 14

Larvae of Triglops scepticus: (A) preflexion, 9.0 mm SL (standard length), UW 059622; (B) flexion, 13.6 

mm SL, UW 105076; (C) postflexion, 18.5 mm SL, UW 105076. Illustrations by B. Vinter.

Larvae of Triglops scepticus have been collected just 

west of Unimak Pass, along the outer shelf east and 

west of Chirikof Island, and in Shelikof Strait (Fig. 13). 

Larvae are collected from April to June.

Pigment. Only eight larvae were available for examination to describe changes in pigmentation during 

development. Larvae of Triglops scepticus have moderate 

pigment on the head and moderate to heavy pigment 

on the gut. In most specimens, postanal pigment is 

restricted to fewer than five PVM and fewer than ten internal melanophores located just above the ventral midline. The PVM are initially external, become embedded 

with development, and are not visible by postflexion. 

Head pigment in preflexion larvae consists primarily 

of dorsal pigment on the forebrain, midbrain, hindbrain, and nape; some pigment is visible on the dorsal 

rim of the orbit. Internal pigment can be seen on the 

side of the midbrain and nape. Several melanophores 

are present on the pectoral-fin base. Pigment on the 

gut is initially moderate and restricted to the dorsal and 

lateral surfaces and surrounding the anus. Pigment on 

the dorsal and lateral surface of the gut becomes heavy 

and ventral pigment develops later in preflexion larvae 

posterior to the isthmus and on the posterior third of 

the gut. Postanal pigment begins as two PVM at 75% 

SL (Fig. 14A). A short series (~10) of internal melanophores just above the ventral midline starting at about 

60% SL is visible, in addition to a third melanophore 

immediately posterior to the other PVM on the larger 

preflexion larva. Five to six melanophores are present 

on the ventral caudal-fin anlage.

Head pigment increases in flexion larvae. Internal 

melanophores on the forebrain and dorsal midbrain 
26 Professional Paper NMFS 10

and both internal and external pigment are present 

on the nape. Pigment is visible on the membrane 

between the upper jaw and snout. Diffuse pigment develops in the posttemporal area, in the preopercular 

area, and in the opercular area even with the midline 

of the eye (Fig. 14B). More pigment develops on the 

pectoral-fin base. The gut is completely pigmented 

except for the anterior one-half to two-thirds of its 

ventral surface and the anus; pigment on the dorsal 

surface is heavier than on the rest of the gut. Postanal 

body pigment may be difficult to see in some flexion 

larvae. In addition to two internal PVM at 75% SL, melanophores may be present on the hypaxial myomeres 

near the developing caudal fin, on the ventral finfold 

of the caudal peduncle, and on the upper and lower 

developing caudal-fin rays.

Pigment continues to increase on the head of postflexion larvae. More internal pigment is present on 

the midbrain, more external pigment is present in 

the preopercular and opercular areas, and pigment is 

visible near the nares. Pigment appears on the lower 

jaw and outlines the edge of the preopercle anterior 

to the spines. A light speckling of pigment appears on 

the nape, near the base of the dorsal spines, and on the 

lateral body over the gut (Fig. 14C). Pigment increases 

from moderate to heavy on the pectoral-fin base. In 

addition to a few pigment spots in the center of the 

isthmus, the anterior edge of the isthmus is lined with 

moderately-spaced melanophores. A few melanophores 

are at the base of the pelvic fins. Pigment on the gut 

is heavy, covering all areas except for the anus, and 

the dorsal surface of the gut appears black; individual 

melanophores are visible under the surface of the skin. 

While most gut pigment is internal, small external melanophores are present on the lateral and ventral surface 

of the gut. No pigment is visible on the postanal body 

in postflexion larvae.

Proportions. Notochord flexion in Triglops scepticus

begins after 9 mm SL and is complete by 18.5 mm SL. 

For those larvae examined, most body measurements 

for T. scepticus increase from preflexion to flexion stage 

and then decrease minimally during postflexion (Table 

2). These are snout to anus length/SL, snout to first 

dorsal-fin length/SL, body depth/SL, head length/

SL, and snout length/HL. Eye diameter/HL decreases 

throughout development. Interorbital width/HL increases in postflexion larvae only. Pectoral-fin length/

SL increases from preflexion to postflexion.

Spination. Ossification of spines could not be determined due to the insufficient number of specimens for 

clearing and staining. A single parietal spine is present 

in preflexion larvae. By flexion stage, single parietal, 

nuchal, and postocular spines and a single row of four 

preopercular spines are present. Nasal spines are present in postflexion larvae and the parietal and nuchal 

spines are overgrown with skin.

Morphological and other character comparisons.

Larvae of Triglops scepticus have a low vertebral count 

(45–46), a low dorsal-fin ray count (21–24), and the 

fewest numbers of PVM, which begin farther away from 

the anus than any other species of Triglops that have a 

PVM series (Table 3). 

In comparison with all other species of Triglops, 

preflexion larvae of T. scepticus have a significantly 

larger eye diameter/HL than all other larvae except 

T. nybelini (Table 4). Flexion larvae of T. scepticus have 

a significantly greater snout to anus length/SL (Appendix 1), greater eye diameter/HL (Appendix 12), 

greater body depth/SL (Appendix 13), and greater 

interorbital width/HL (Appendix 14) than all other 

larvae. Postflexion larvae of T. scepticus have a significantly greater snout to anus length/SL than all 

larvae except T. murrayi (Table 4) and a significantly 

greater body depth/SL than all larvae except T. macellus (Table 4).

In comparison with larvae in the Pacific group of species, preflexion larvae of Triglops scepticus have a significantly larger eye diameter/HL than all other larvae (Appendix 8). Flexion larvae of T. scepticus have a significantly 

greater snout to anus length/SL (Appendix 1), greater 

body depth/SL (Appendix 3), and larger eye diameter/

HL (Appendix 10) than all other larvae. Postflexion larvae of T. scepticus have a significantly greater snout to anus 

length/SL than all other larvae (Appendix 15).

Discussion

Identification of most larval Triglops was not possible 

prior to Pietsch’s (1993) revision of the genus; adult 

meristic counts were either lacking or overlapping, 

thus preventing differentiation of most species at all 

stages. Revised meristics enabled identification of most 

late flexion and postflexion larvae; for T. forficatus, the 

high vertebral count permitted positive identification 

at all stages. Pigment patterns of larvae with full meristic counts were used to identify younger larvae. This 

process allowed identification of most of our specimens of Triglops collected in the North Pacific Ocean 

and Bering Sea (poor condition of a small number of 

larvae prevented identification to species). Although 

larvae of Triglops scepticus were identifiable on the basis 

of pigment pattern and body morphology, there were 

few specimens available for examination. Existing morphological data and pigment characters may change 

as more specimens are collected. Of larvae reported 

in the literature, Triglops A as presented by Matarese 
27

et al. (1989) is probably T. pingeli; the meristic counts 

(as illustrated: 46–47 myomeres, 22 anal-fin rays, 17 

pectoral-fin rays), large head spines, and presence of 

two postocular spines on the 16.9-mm larva are nonoverlapping characters for this species. Triglops sp. 

described by Richardson and Washington (1980) is 

probably T. macellus, as surmised by the authors. The 

myomere count is low (47), but the pectoral fin count 

(16) is too low for any other co-occurring species. Also, 

the pattern of heavy pigment on the gut and absence 

of pigment on the postanal body is exclusive to T. macellus. Larvae illustrated by Blackburn (1973) appear 

to resemble the larvae described by Richardson and 

Washington (1980); however, median and caudal-fin 

rays are shown as forming on the 8.3-mm larva and 

none of the larvae described herein begin fin-ray 

development at that size. Also, the ventral gut area is 

unpigmented on the 12-mm larva; the entire gut of 

our T. macellus larvae is pigmented at that size. Identification of these larvae may not be possible without 

myomere counts.

Identification of the three species co-occurring in the 

western North Atlantic Ocean is difficult because of the 

large degree of overlap of many meristic characters. 

The description of Triglops murrayi larvae presented 

here differs from published identifications, but is most 

similar to that of Khan (1972). Some of our larvae 

developed dorsolateral and ventrolateral postanal 

pigment at about 10 mm SL that was not described by 

Khan (1972). Pavlov et al. (1992) described dorsolateral pigment on 12.0 and 14.2-mm larvae. They also 

described dorsal midline pigment on 14.2 and 20.2-mm 

larvae, which was not reported by Khan (1972) or Fahay 

(1983, 2007). The dorsolateral and dorsal midline pigment illustrated on the larvae in Pavlov et al. (1992) is 

found in T. nybelini; however, the dorsal-fin-ray count 

for the 20.2-mm larva (22) is specific for T. murrayi. 

Light speckled pigment along the dorsal midline was 

present only on our largest postflexion larva (23.4 mm 

SL) and may be the beginning of juvenile pigment. 

Fahay (2007) described flexion in T. murrayi occurring 

at 12 mm or larger; however, flexion was evident in our 

larvae as early as 10.5 mm SL. 

The single published description of Triglops nybelini

(27 mm SL; Dunbar and Hildebrand, 1952) lists the 

pectoral-fin-ray count of 22 and large eye as diagnostic 

characters of the species, and in addition describes the 

dark line of pigment extending along the dorsal midline from the front of the first dorsal fin to the caudal 

fin. Dorsal midline pigment first appears during early 

flexion in our larvae of T. nybelini along the base of the 

developing dorsal-fin rays. Dorsal notochord pigment, 

which is unique to this species, appears in late preflexion and persists through midflexion. As with Triglops 

scepticus, there were few specimens of T. nybelini available for examination. Morphology data and pigment 

characters may change as more specimens are collected.

Published identifications of larvae of Triglops pingeli

are incomplete, and several are based on misidentified 

specimens. Rass (1949) illustrated a 10-mm larva from 

the Barents Sea with dorsal midline pigment, a very 

large eye (50% HL), and a protruding lower jaw; this last 

character was described by Pietsch (1993) as peculiar to 

adult T. nybelini among species of Triglops found in that 

area. The eye diameter of T. pingeli is smaller than the 

eyes of all other Triglops larvae at all stages of development (Appendices 10, 12–13) and adults have smaller 

eyes than most Triglops (Pietsch, 1993). Therefore, the 

larvae in Rass (1949) is most likely T. nybelini. Koefoed 

(1907) described eight larvae as T. pingeli; however, the 

five largest larvae (18.5–22.0 mm) have dorsal-fin-ray 

counts of 22, which indicates they could only be T. murrayi. The dorsal (25) and anal-fin-ray count (25) for the 

16.5-mm larva of Koedfoed (1907; Fig. 5) could identify 

this larva as either T. pingeli or T. nybelini. The illustration shows dorsal midline and lateral line pigment, 

which was apparent on none of our T. pingeli specimens, 

and is more like pigment belonging to larvae of T. nybelini rather than those of T. pingeli. 

The genus Triglops is morphologically distinct from 

other cottids, but there is no consensus as to its relationship to other members of the family. Larval morphology 

of Triglops was examined by Richardson (1981) who 

placed the genus in a phenetic group of five genera 

that share body shape (pointed snout, slender body), 

pigment characters (heavy pigment on dorsal surface 

of the gut and a PVM series), and the presence of four 

preopercular spines. In an unpublished study based on 

osteological characters by Washington and Richardson 

(Washington et al., 1984), an additional eight genera 

were added to Richardson’s (1981) group on the basis 

of the presence of a distinct preopercular bony shelf 

and other head spines. Although this group (the Myoxocephalus group) is the least well-defined of the cottid 

groupings, the external morphological characters used 

by Richardson (1981) corresponded well with osteological characters used in the later study. However, no close 

affinities between Triglops and other genera within this 

group could be ascertained. 

Yabe (1985) examined morphological characters of 

adults and proposed Triglops to be a sister group of a 

“Radulinus-group” that included Radulinus, Asemichthys, 

and Astrocottus. Smith and Wheeler (2004) reanalyzed 

Yabe’s (1985) work and found Triglops to have close ties 

to no other cottid genera, which was the same outcome 

to their own genetic analysis. Further analysis combining morphological data, ontogenetic characters, and 

expanded molecular data, as suggested by Smith and 

Wheeler (2004), may clarify the position of the genus 

Triglops within the family Cottidae.
28 Professional Paper NMFS 10

Acknowledgments

We thank B. Vinter (AFSC, retired) for illustrations of 

the larvae and taxonomic assistance, M. Busby (AFSC) 

for image analysis programming, K. Mier (AFSC) 

for statistical support, and W. Carlson, L. De Forest 

(AFSC), and R. Cartwright (formerly AFSC) for graphics support. Early in the project, L. Van Guelpen (ARC) 

provided samples, support, and taxonomic discussions; 

he later reviewed the manuscript and provided helpful 

comments and thoughtful improvements. J. Marliave 

and his former assistant, D. Kent (Vancouver Public 

Aquarium), provided samples and taxonomic discussions. M. Busby and J. Orr (AFSC) initially reviewed the 

manuscript. Three anonymous reviewers provided detailed comments and suggestions. This research is contribution EcoFOCI-0739 to the National Oceanic and 

Atmospheric Administration’s Fisheries-Oceanography 

Coordinated Investigations.

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Appendices

Appendix 1

Comparison of morphometric measurements of flexion larvae of Triglops, snout to anus length vs. 

standard length. Other species represented by solid lines and black dots are T. macellus, T. murrayi, T. 

pingeli, and T. nybelini. Symbols represent measured values for each species; lines represent equations 

generated by analysis of covariance (P<0.05).

tematics of fishes, H. G. Moser, W. J. Richards, D. M. Cohen, 

M. P. Fahay, A. W. Kendall, Jr., and S. L. Richardson (eds.), 

p. 438–447. Spec. Publ. 1, Am. Soc. Ichthyol. Herpetol. Allen 

Press, Lawrence, KS, 760 p.

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30 Professional Paper NMFS 10

Appendix 2

Comparison of morphometric measurements of flexion larvae of Pacific species of Triglops (T. forficatus,

T. macellus, T. pingeli, and T. scepticus), snout to first dorsal-fin length vs. standard length. Other species 

represented by solid lines and black dots are T. macellus, T. pingeli, and T. scepticus. Symbols represent 

measured values for each species; lines represent equations generated by analysis of covariance (P<0.05).
31

Appendix 3

Comparison of morphometric measurements of flexion larvae of Pacific species of Triglops (T. forficatus,

T. macellus, T. pingeli, and T. scepticus), body depth vs. standard length. Other species represented by solid 

lines and black dots are T. macellus and T. pingeli. Symbols represent measured values for each species; lines 

represent equations generated by analysis of covariance (P<0.05).
32 Professional Paper NMFS 10

Appendix 4

Comparison of morphometric measurements of preflexion larvae of Triglops, snout length vs. head length. 

Other species represented by solid lines and black dots are T. forficatus, T. murrayi, T. pingeli, T. nybelini, and 

T. scepticus. Symbols represent measured values for each species; lines represent equations generated by 

analysis of covariance (P=0.10).
33

Appendix 5

Comparison of morphometric measurements of flexion larvae of Atlantic species of Triglops (T. murrayi, T. 

nybelini, and T. pingeli), pectoral-fin length vs. standard length. Symbols represent measured values for each 

species; lines represent equations generated by analysis of covariance (P<0.05).
34 Professional Paper NMFS 10

Appendix 6

Comparison of morphometric measurements of preflexion larvae of Atlantic species of Triglops (T. murrayi,

T. nybelini, and T. pingeli), eye diameter vs. head length. Symbols represent measured values for each 

species; lines represent equations generated by analysis of covariance (P<0.05).
35

Appendix 7

Comparison of morphometric measurements of flexion larvae of Atlantic species of Triglops (T. murrayi, T. 

nybelini, and T. pingeli), eye diameter vs. head length. Symbols represent measured values for each species; 

lines represent equations generated by analysis of covariance (P<0.05).
36 Professional Paper NMFS 10

Appendix 8

Comparison of morphometric measurements of preflexion larvae of Pacific species of Triglops (T. forficatus,

T. macellus, T. pingeli, and T. scepticus), eye diameter vs. head length. Other species represented by solid lines 

and black dots are T. forficatus and T. macellus. Symbols represent measured values for each species; lines 

represent equations generated by analysis of covariance (P<0.05).
37

Appendix 9

Comparison of morphometric measurements of flexion larvae of Pacific species of Triglops (T. forficatus, 

T. macellus, T. pingeli, and T. scepticus), snout length vs. head length. Other species represented by solid lines 

and black dots are T. forficatus, T. macellus, and T. scepticus. Symbols represent measured values for each 

species; lines represent equations generated by analysis of covariance (P<0.05).
38 Professional Paper NMFS 10

Appendix 10

Comparison of morphometric measurements of flexion larvae of Pacific species of Triglops (T. forficatus, 

T. macellus, T. pingeli, and T. scepticus), eye diameter vs. head length. Other species represented by solid lines 

and black dots are T. forficatus and T. macellus. Symbols represent measured values for each species; lines 

represent equations generated by analysis of covariance (P<0.05).
39

Appendix 11

Comparison of morphometric measurements of postflexion larvae of Pacific species of Triglops (T. forficatus,

T. macellus, T. pingeli, and T. scepticus), eye diameter vs. head length. Other species represented by solid lines 

and black dots are T. forficatus, T. macellus, and T. scepticus. Symbols represent measured values for each 

species; lines represent equations generated by analysis of covariance (P<0.05).
40 Professional Paper NMFS 10

Appendix 12

Comparison of morphometric measurements of flexion larvae of Triglops, eye diameter vs. head length. 

Other species represented by solid lines and black dots are T. forficatus, T. macellus, T. murrayi, T. nybelini, 

and T. pingeli. Symbols represent measured values for each species; lines represent equations generated by 

analysis of covariance (P<0.05).
41

Appendix 13

Comparison of morphometric measurements of flexion larvae of Triglops, body depth vs. standard length. 

Other species represented by solid lines and black dots are T. forficatus, T. macellus, T. murrayi, T. nybelini, 

and T. pingeli. Symbols represent measured values for each species; lines represent equations generated by 

analysis of covariance (P<0.05).
42 Professional Paper NMFS 10

Appendix 14

Comparison of morphometric measurements of flexion larvae of Triglops, interorbital width vs. head length. 

Other species represented by solid lines and black dots are T. forficatus, T. macellus, T. murrayi, T. nybelini, 

and T. pingeli. Symbols represent measured values for each species; lines represent equations generated by 

analysis of covariance (P<0.05).
43

Appendix 15

Comparison of morphometric measurements of postflexion larvae of Pacific species of Triglops (T. forficatus,

T. macellus, T. pingeli, and T. scepticus), snout to anus length vs. standard length. Other species represented 

by solid lines and black dots are T. forficatus, T. macellus, and T. pingeli. Symbols represent measured values 

for each species; lines represent equations generated by analysis of covariance (P<0.05).

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