School- based sea hare research

March 6, 2002
From: Amy Dohnt

Dear Sirs,
I am a senior student at Geraldton secondary college, Western Australia, and i am involved in a school based marine science course. i would greatly appreciate any information you can provide on the life science of the sea hares, specifically Aplysia extraordinaria. We are planning to study these creatures within a closed environment that we have created here at school, and we are seeking information which will better enable us to create the ideal environment for them to live in. Details on feeding and breeding habits would also be well received.
Your efforts are appreciated and your web site is excellent.
Yours in science,
Amy Dohnt, Sam Nairn and Evan Bain

Dohnt, A., 2002 (Mar 6) School- based sea hare research. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Amy, Sam and Evan,
Firstly you are probably better to use the name Aplysia gigantea for the big Western Australian sea hare. In eastern Australia we call a very similar animal Aplysia extraordinaria. If the two do turn out to be the same then we would use Aplysia gigantea, as it is a much older name.

I see from Peter Taylor's message that this large Sea Hare is causing a problem for the dogs of Geraldton at present. Mass Mortality seems to be a normal part of the Sea Hare's life cycle.

Aplysia gigantea is one of the biggest of the Sea Hares so keeping it in captivity will mean you will probably need to work on a larger scale than if you were keeping a smaller species alive. Have a look at the Sea Hares Page for links to other places in the Forum with information on Sea Hares. Also you will find a lot of information in the earlier messages on sea hares and my comments, that are attached at the bottom of each page.

You don't mention whether your 'closed environment' will be an aquarium system or perhaps outdoor ponds? Whatever you use it will be essential that you have some way of keeping the seawater clean and oxygenated, preferably by some sort of circulating system. In the wild, sea hares feed on algae, usually species of green or red algae. Different species of Sea Hare prefer different algae so I guess you will have to test some locally available and relatively abundant algae to see what they will eat. Many sea weeds produce and exude nasty chemicals so it pays not to put too much algae in the water at any one time. The sea lettuce Ulva is eaten by most Sea Hares so if it is abundant it is a good fallback food. Some people boil ordinary lettuce for a short time and feed that to Sea Hares with success so that's another possibility.

As for breeding a second generation that could be a problem. Sea hares breed quite easily in captivity and produce long tangled strings of eggs. Unfortunately the eggs develop into small free-swimming planktonic larvae which need to spend some time in the plankton feeding on microscopic algae. Keeping these larvae alive in aquarium conditions is very difficult.

Good Luck with your project. Keep in touch and let me know if you have any problems,
Bill Rudman

Rudman, W.B., 2002 (Mar 6). Comment on School- based sea hare research by Amy Dohnt. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Aplysia gigantea

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