Crowned nudibranch on its host bryozoa
Photo by Jeff Corbett
Two crowned nudibranchs mating
A twin-crowned nudibranch - count the yellow-tipped apendages around the gills - there are six, compared to the crowned nudibranchs' two.
An orange-lined crowned nudibranch, with white gills and only the tips of the rhinophores black - unlike both the crowned and twin-crowned nudibranchs
Photos by Guido Zsilavecz
The crowned nudibranch Polycera capensis is one of the more common species found around the peninsula, and is easily recognizable by its white body, and yellow-tipped crown, as well as a variable amount of black. They are most often found on dark bryozoans, on which they feed, and on which one can often see their egg ribbons.
Even though it is hard to mis-identify it, care must be taken to do so properly, as there is one more species, and possibly another one which are extremely similar. The second species, the twin-crowned nudibranch Polycera sp.1, differs in that around the gills there are not just two yellow-tipped appendages, but instead there are four or, more commonly, six. The third species, whose status as species it not yet confirmed, and which we called the orange-lined crowned nudibranch Polycera sp.2, has no black but instead orange lines (even if barely present), and, if one looks closely, does not have completely black rhinophores and gills, being at most black-tipped. These features are consistent enough to set them apart.
For more details see "Nudibranchs of the Cape Peninsula and False Bay", now available from SURG and better Cape Town dive shops.
Nudibranchs of the Cape Peninsula and False Bay, G. Zsilavecz, 2007.
Nudibranchs of Southern Africa - a guide to the opisthobranch molluscs of southern Africa, T. Gosliner, 1987.