NOTE Tucker and Alshuth. Development of laboratory-reared Archossrgus probatocephalus 
395 
from larvae and juveniles with a stereomicroscope: 
caudal rays, dorsal spines and rays, anal spines and 
rays, pectoral rays, and pelvic spine and rays. 
Results and discussion 
Egg development 
The planktonic eggs were spherical. The chorion was 
transparent and smooth; the yolk clear, homoge- 
neous, and unpigmented; and the single oil globule 
yellow. The perivitelline space was very narrow ( 12- 
39 pm before fertilization, 10-48 pm at 5 haf, and 
31-77 pm at 28 haf). Diameter of live eggs at 2.5 haf 
was in the range of 806-865 pm (mean 824 pm) and 
was constant until hatching; oil globule diameter 
range was 187-241 pm (mean 206 pm). At 2.5 haf, 
mean yolk volume was 254 nL and oil globule vol- 
ume was 4.58 nL (Fig. 1). Just before hatching (Fig. 
2A), the embryo had sparse pigmentation on the 
snout and behind the eye. Several punctate melano- 
phores were present on the oil globule. At 23°C, about 
90% of the eggs hatched at 28 ±0.5 haf. 
Larval development 
Hatchlings had unpigmented eyes, undeveloped 
mouths, and clear finfolds (ranges 1.58-1.70 mm NL, 
1.68-1.78 mm TL, Fig. 2B). The pigmented oil glob- 
ule was near the posterior margin of the unpigmented 
yolk sac, close to the anus. Distinct melanophores 
were visible on the ventral midline, halfway between 
the anus and the notochord tip. Several small con- 
tracted melanophores were on the body, but no dis- 
tinct pattern was seen in the examined material. 
Sixty-seven percent of the yolk remained and 70% 
of the oil (Fig. 1). At 15 hah (h after hatching), 
pigmentation was not visible. At 25 hah, live lar- 
vae had five distinct vertical bands of yellow pig- 
ment, one above the yolk sac, three between the 
anus and the notochord tip, and one at the noto- 
chord tip (Fig. 2C; yellow pigment not shown here, 
but see photograph in Tucker, 1986). Six percent 
of the yolk remained and 33% of the oil (Fig. 1 ). At 
45 hah, eyes were only partly pigmented, and the 
mouth was not yet open. Except for the eyes, no 
pigmentation was visible in preserved specimens. 
Two percent of the yolk remained and 10% of the 
oil (Fig. 1). Between 3 and 4 dah (d after hatch- 
ing), nearly all larvae developed functioning di- 
gestive systems and fully pigmented eyes and be- 
gan to feed on rotifers. Lower jaw length averaged 
0.29 mm. Pigmentation was present on the ven- 
tral surface of the gut and anus. Some melano- 
phores were visible along the ventral midline. At 73 
hah, only 0.2% of the yolk remained and 0.4% of the 
oil (Fig. 1). At 4.0 dah, larvae were feeding efficiently 
(Fig. 3A). Rayless pectoral fins were present at 2.37 
mm NL. Pigmentation was sparse. Melanophores on 
the head had disappeared, and those on the gut had 
contracted. Dendritic melanophores were visible on 
the surface of the gut and were densest on the dorsal 
surface. Several distinct melanophores were on the 
ventral midline. No fin rays were visible. In at least 
half the specimens, yolk and oil were exhausted; the 
rest had a trace. At 5.0 dah, shape and pigmentation 
had not changed appreciably, but by 6 dah, all lar- 
vae had melanophores on the gut, as well as preanal 
and postanal pigmentation on the ventral midline. 
At 9 dah, nine larvae (2.78-3.24 mm NL) were still 
in preflexion (Fig. 3B), and one (3.50 mm NL) had 
begun notochord flexion. Pigmentation was as for 6 
dah. Number and position of branching melano- 
phores on the ventral midline were variable. The 
larva undergoing notchord flexion also had internal 
melanophores in the center of the auditory vesicle, 
one branched melanophore on the forehead, and 
melanophores on the lower jaw angle and throat. At 
14 dah, two larvae (4.16-4.66 mm NL) were in 
preflexion and eight (4.66-5.36 mm NL) in flexion. 
Four of the flexion specimens were in early flexion 
and four in midflexion. Rays began forming above 
the center of the pectoral fin at 4.66 mm NL and just 
below the center of the caudal fin at 4.91 mm NL 
(Table 1). 
At 17 dah, all 10 specimens were in midflexion. Cau- 
dal rays continued to develop. Rays began forming in 
the posterior part of the soft dorsal fin at 5.29 mm NL 
and in the posterior part of the anal fin at 5.36 mm NL. 
Larvae had two melanophores on the forehead, four 
Hours after fertilization 
Figure 1 
Yolk and oil globule depletion in sheepshead, Archosargus 
probatocephalus , eggs and larvae. Triangles represent yolk 
and dots represent oil. 
