Sea Hare? swimming

January 18, 2003
From: Jessica Vivien

I used to live in Fremantle [SW Western Australia] in 1995, and I swam most mornings in summer in the Indian Ocean, at South Beach. Over a period of about a month, there was an influx of small swimming things that fluttered along near the surface of the water, making for the shallows. They were a greeny-brown, mottled, from about 1 to about 5 inches long, with a separate head formed a bit like a sea dragon but not very leafy, and they swam by undulating a membrane "skirt" that extended from the sides of their bodies. Many got washed onto the sand by the waves. I didn't see any of them mating but assumed that was possibly the reason for the gathering,- or could they have been stirred up by a storm out to sea or something? They looked a little like seahares, Aplysia dactylomela but do seaslugs swim? These didn't go lower than a foot or so under the surface and certainly did not crawl along the rocks.
What do you think they were?

Vivien, J. , 2003 (Jan 18) Sea Hare? swimming. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Jessica,
I am sure you are describibg a swimming Sea Hare. Quite a few sea slugs can swim, and this includes some Sea Hares. Have a look at Julie Marshall's photo of the eastern Australian Aplysia extraordinaria swimming. Your swimming companions were almost certainly Aplysia gigantea, which you will see from other messages on this page is a common Western Australian swimmer.

For further information on swimming open the Forum's SEARCH facility and search for swimming. That should give you a list of messages and other information on swimming sea slugs.
Best wishes,
Bill Rudman

Rudman, W.B., 2003 (Jan 18). Comment on Sea Hare? swimming by Jessica Vivien . [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Aplysia gigantea

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