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.