Oplegnathidae: F II A7

Oplegnathus conwayi Richardson, 1840

Cape knifejaw

Egg diameter in µm	Number of oil globules	Diameter of oil globule in µm	Yolk texture	Perivitelline space	Position of oil globule at hatch	Gut length   at eye- pigment stage	Myomeres
1010-1150	1	240-265	segmented	narrow	stern	45% of NL	26

Egg: The oil globule is light amber to amber, and the egg has an amber hue on a white background (A & B). Lemon yellow and black stellate pigment spots are all over the embryo. There are a few yellow pigment spots dorsally on the oil globule, and black spots ventrally. Later dark pigment spots are also seen on the yolk (B).  In some eggs the embryo pigment can appear green, presumably due to a particular blend of black and yellow pigment spots.. Incubation is about 45 hours (22°C).

Larva: The newly hatched larva has black pigment dots scattered in the dorsal finfold, and stringy black pigment spots on the yolk (C).  Four bands of yellow pigment occur down the body, the first around the eyes (C), which persist to day 6 (E). A larva reared to 24 days, is just past flexion (F).  C: 1 day, D: 3 days, E: 6 days, F: 24 days (22-23°C).

This species was not reared past 24 days. Eight hatched larvae have been sequenced, and match the DNA sequence of 2 adults collected locally (BOLD). See also EIIIA2.

 

Linked samples	Offshore	Inshore
Eggs	44	31
Hits	15	13

This species is a spring spawner, with September and October the peak months (blue graph). The annual collection of eggs at Park Rynie (white graph), shows no clear  pattern. The Park Rynie linked samples had 59% of these eggs offshore, indicating spawning is quite shallow, around the 30m depth contour. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.