Opisthobranch of the Week Data
Aegires citrinus is considered to be uncommon on Okinawa as I have collected a total of 17 individuals since 24 April, 1984. Perhaps an additional 6-8 individuals have been photographed but not collected.
The following Aegires species are known from the waters of Okinawa:
The bright lemon color of Aegires citrinus readily distinguish it from the black mottling of A. gardineri, a closely related species. Both of these animals have a relatively rigid body and move so slowly that someone seeing these animals alive for the first time, frequently is amazed to discover the apparent inert mass is indeed a nudibranch. In the case of A. serenae, see the species description on the page featuring A. serenae. All three animals are sponge feeders and are frequently found associated with calcareous sponges belonging to the genus Leucetta.
My experience in finding this brightly pigmented dorid is to look for the bright yellow calcareous sponge, Leucetta, upon which this animal is frequently found feeding. In as much as the dorid greatly mimics the color of the sponge, it often requires a close inspection of the sponge in order to discover Aegires citrinus. Occasionally the nudibranch in found slowly crawling in the open, presumably in search for its prey; when the nudibranch is not on the sponge, it sticks out like the proverbial sore thumb. The sponge, and therefore the dorid, are frequently found amid the interstices of a live stony coral reef, as well as at the reef forefront, commonly between ten and thirty feet of Okinawan waters.