July 15, 2006
From: Trevor McMurrich
I found this nudi on a small man made reef next to the shore. Could you identify it please?
Locality: Indented Heads, 1 metre, Victoria, Port Phillip Bay, 20 Jume 2006, shallow reef. Length: 15 mm. Photographer: Trevor McMurrich.
McMurrich, T.B., 2006 (Jul 15) Hermaea from Victoria, Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/17004
Although it looks like a nudibranch, it is in fact a member of another sea slug group which we call the sacoglossans. They are all herbivores and feed by sucking the cell contents from particular algae. Most species of Hermaea feed on red algae and have a pinkish colouration. I have included a close-up showing the red algae you found the animal on. I am pretty sure your animal is Hermaea evelinemarcusae, but I have a few doubts. Your animal seems to have many more cerata than usual for the species, and they seem arranged in a very regular pattern. Species of Hermaea often discard cerata, much like a lizard drops its tail, when attacked, so it could be that this animal has led a charmed life and has not needed to discard any of its cerata.
The darker branching in the cerata, which you can see in the close-up alongside, are the branching ducts of the digestive gland, where food is digested and absorbed.