WALSH and LUND: EARLY DEVELOPMENT OF LONGHORN SCULPIN 



yolk sac. Pectoral fins were larger and were first seen 

 to make intermittent fluttering motions. Mouth was 

 open. Embryos exhibited considerable movement 

 within the eggs, including complete rotations (Fig. 

 3F). 



Hatching of eggs occurred between 36 and 65 d 

 after fertilization. Newly hatched longhorn sculpin 

 prolarvae ranged from 6.2 to 7.8 mm TL (mean 6.8 

 mm) and 6.0 to 7.2 mm SL (mean 6.4 mm). Yolk sac 

 averaged 1.2 mm (range 1.1-1.3 mm). Oil droplet was 

 0.4 mm (range 0.3-0.5 mm) and transparent. Eye was 

 darkly pigmented, and choroid fissure was apparent. 

 Bulging of the lens could best be seen from the dorsal 

 view. Mouth was wide open in some specimens, but 

 did not yet appear well developed. A pair of olfactory 

 buds flanked a deep pit located on the midline 

 anterior to the eyes. Auditory vesicles were large and 

 could be seen to protrude when viewed from above. A 

 few stellate chromatophores were present above and 

 behind the auditory vesicles. Some specimens had a 

 single large stellate melanophore at the anterior end 

 of the yolk sac near the oil globule. Dorsal surface of 

 the yolk sac was densely covered by contracted 

 chromatophores. A series of spots were present along 

 the ventral line of the tail and ranged in number from 

 18 to 28. Larvae had 37 or 38 myomeres. Anus was 

 situated just anterior to the ventral origin of the fin- 

 fold. Dorsal finfold originated posterior to the 

 auditory vesicles and had a smooth margin; its caudal 

 portion was lunate. Pectoral fins had broad bases and 

 were approximately as deep as they were wide 

 (Fig. 4A). 



Absorption of the yolk sac was completed about 10 

 d after hatching. Postlarvae averaged 7.7 mm TL 

 (range 7.1-8.3 mm). Although reduced in size, a rem- 

 nant of the oil globule was present. The mouth was 

 well developed. In most specimens, a pair of small 

 head spines and 3 or 4 preopercular spines were vis- 

 ible. A pair of nostrils flanked the nasal pit. The eyes 

 retained the fissure. Most specimens had a single 

 large stellate ehromatophore above and posterior to 

 the uppermost cheek spine. The other major change 

 in pigmentation was the approach of dense contract- 

 ed chromatophores toward the anus. Pectoral fins 

 increased in size and were deeper than wide. Larvae 

 had 37or38 myomeres. Stomach and liver were vis- 

 ible. Finfold was smooth and continuous (Fig. 4B). 



Absorption of the oil globule was completed at 

 about 15-20d, when larvae averaged 8.7 mm TL 

 (range 8.3-9.1 mm). Larvae at this stage exhibited 

 large stellate melanophores scattered over the top of 

 the head, and on the midline above and between the 

 nostrils. Several stellate chromatophores were 

 present on the isthmus. Additional stellate melano- 



phores developed almost down to the anus, beyond 

 the extent of the contracted chromatophores. 

 Several contracted chromatophores were posterior 

 and parallel to the cleithrum. Margins of the pec- 

 torals were ragged in appearance. In most specimens, 

 incipient rays of the caudal fin became visible. Four 

 preopercular spines were present on each cheek. One 

 pair of spines was well developed on the crown of the 

 head above the auditory vesicles. Nostrils appeared 

 slightly larger. Fissure of the eye remained visible. 

 Ventral spots on the tail ranged in number from 16 to 

 24. Finfold was smooth and continuous (Fig. 4C). 



Among larvae which were 25-30 d old, the head was 

 more densely pigmented, including the presence of 

 some contracted chromatophores on the crown and a 

 few stellate chromatophores within the auditory 

 vesicles. Pigmentation was also increasing posterior 

 to the auditory vesicles. There were four spines along 

 the operculum and one pair of spines on the crown of 

 the head. Fissure of the eye was difficult to see. 

 Caudal rays were more clearly visible. Pectoral fins 

 appeared more thick and fleshy at their bases, where 

 1-3 stellate chromatophores were located. Some 

 specimens had incipient pectoral rays. Pelvic buds 

 were present. The margin of the finfold was slightly 

 ragged (Fig. 4D). 



The onset of development of dorsal and anal fins 

 was observed at 33-40 d, when larvae were about 9.0 

 mm TL. Some larvae at this stage had an anlage of the 

 dorsal fin, whereas the larger specimens possessed 

 the rudiments of 9 dorsal spines, 6 dorsal rays, and 13 

 anal rays. Pectoral fins had 15 or 16 rays, and the 

 stellate chromatophores at the anterior margin of the 

 fin had increased in number from 7 to 10. Caudal fin 

 had 9-12 rays, and the hypurals were present. Pelvic 

 fins appeared slightly larger. The crown of the head 

 was densely pigmented with stellate and contracted 

 melanophores. Dark vertical bars were located pos- 

 terior to the auditory vesicles. Four spines were 

 present on each cheek and two pairs of spines were 

 present on the crown. The nostrils were beginning to 

 constrict. The notochord was not yet flexed (Fig. 

 5A). 



Forty-eight day larvae measured about 10.5 mm 

 TL. They exhibited a first dorsal fin with 9 spines, 

 and a second dorsal with 14 rays. The first dorsal was 

 lower than the second, the two were continuous, and 

 the finfold remained complete in the region of the 

 caudal peduncle. Anal fin had 1 4 rays. Caudal fin had 

 13 or 14 rays, and urostyle pointed dorsally. Pelvic 

 fins were somewhat larger, but the rays were not yet 

 visible. Pectoral fins were large and fanlike; these had 

 17 or 18 rays and the bases of the fins were well 

 pigmented. The pigmentations of the crown of the 



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