Carapidae: BK III A1


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


960-1000 x 790-820






25% of NL


Egg: The bright, wine-red oil globule and oval egg shape, make this species instantly recognisable. The egg shows some size variation. Before hatching, no pigment is visible on the developing embryo. It can be separated from the other known carapid egg, ABKIIIA1, by its significantly bigger oil globule.

Larva: The newly hatched larva is elongate, with a short gut, tucked in against the rear of the yolk (B). An edge of white pigment is present dorsally, at the tip of the notochord (B). The 3-day larva develops dense pigment in the head region (C), while retaining the white pigment on the tail (D). The eyes and mouth are not fully developed at three days, but an indentation in the dorsal finfold just behind a vertical line from the anus (white arrow), indicates development of a vexillum (D).  B: NH, C & D: 3 days.

Several attempts were made to rear this species, unsuccessfully. Seven hatched larvae have been barcoded, indicating 2 species, but neither group has found a match among currently available adult sequences. Onuxodon parvibrachium, and O. margaritiferae are the only South African carapids that have been successfully sequenced, but do not group closely with either of the two BKIIIA1 egg groups in the dendrogram, nor with ABKIIIA1 (BOLD).

This egg was common in the Park Rynie samples (Introductory notes, Section 7, Table 3), but was not seen in Durban Harbour Mouth samples. The species appear to spawn throughout the year, with a peak in spring and early summer (blue graph). It has been seen in samples more often in recent years (white graph).

linked samples









The eggs were considerably more common in the offshore portion of the Park Rynie linked samples (88%), indicating spawning on or outside the 50m contour, but the picture is clouded by the presence of at least two species. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.