Fiery nudibranchs on the eggs of Acanthodoris.
Fiery nudibranchs on their own eggs
Acanthodoris sp. All photos Guido Zsilavecz
The fiery nudibranch Okenia amoenula is quite a familiar sight on most vertical reef walls, at locations such as Castle Rock, Windmill or A-Frame. It is generally seen in small groups, and very often on its own egg cases. These cases are a somewhat coiled flat white band. On a dive recently we saw some sitting on a different egg case - that of Acanthodoris sp., probably feeding on it. Members of the okeniidae are known to feed mostly on bryozoans, but we could not for certain find out what the fiery nudibranch feeds on - so it is not certain that they are eating the eggs, but given their position, it is most likely.
Two Acanthodoris (an undescribed species) were found about 10 cm from their egg cases, as usual well hidden at the edge of overgrown reef. They are very cryptic nudibranchs, with a rough, papillate skin in a drab light brown. The best way to identify them is that the tips of the rhinophores (the "antenna") are pale, and stand out.
Nudibranchs of Southern Africa - a guide to the opisthobranch molluscs of southern Africa, T Gosliner, 1987.