September 3, 2002
From: James Stein
I recently purchased some Caulerpa from a marine store in Tampa, Florida [USA]. I have no idea where the algae came from but I would suspect off the coast of Tampa somewhere. I was pleasently suprised to find one of these critters in my tank after putting the algae in it. Much to my suprise I've counted now a total of 5 of them and they are literally covering every surface they can find with spirals of green eggs. They are all about 1 inch to 1 1/2 inches in length now and have a habit of entwining themselves in groups of 3 or more. I'm interested in finding out exactly what they are. They aren't particularly pretty or colorful but are still quite interesting to watch. Any help would be greatly appreciated.
email@example.comStein, J., 2002 (Sep 3) Unknown stowaway on Caulerpa. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/7875
Your little animal is the Caribbean species Oxynoe antillarum. It feeds on Caulerpa, so that is obviously how it arrived in your aquarium. If you can take a photo of the egg masses it would be a nice addition to the Forum.
They have a transparent shell which is hidden between the two flaps of skin [parapodia] behind the head. Oxynoe is a sacoglossan sea slug, a group which includes the shell-less Elysia crispata which you may be familar with. All sacoglossans feed by stabbing a hole through the cell wall of the algae that they feed on, and then sucking out the cell contents.
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