Sea Hares and Inking

March 22, 2001
From: Melanie

Thank you for your reply concerning sea hares and burrowing. Now, I have a question about the use of ink by sea hares. Generally it is believed that sea hares dispel ink as a defensive mechanism. However, I have read several papers that question this proposing it may just be a warning, using a foul tasting mucous that they extrude as their primary defense. One of the papers noted how when sea hares were first approached and grabbed by sea anemones as prey, they did not exude their ink. Only upon more tactile pressure did they ink. If you could provide any information on sea hares and inking I would greatly appreciate it. We are in the middle of setting up an exhibit on inking via various molluscs here at the Mote Marine Lab in Sarastoa, Florida, USA.
Thanks for all your help.

Melanie, 2001 (Mar 22) Sea Hares and Inking. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Melanie,
If you have a look at the top of this page I have put your message on, you will find some links to more information on the subject. Also have a look at the messages below yours on this page, and on the other pages referred to, as they also contain more information and references. Basically I don't think there is any good evidence that inking is a defensive strategy in Sea Hares. I think the superficial similarity between their ink and that of octopuses led to this idea, but as they can neither hide in it or run away quickly, the similarity with octopuses isn't very sustainable on close examination.

Your question on burrowing turned out to be quite useful as it has led to an interesting observation by Don Barclay that the tropical Sea Hare Dolabella auricularia does indeed burrow.
Best wishes,
Bill Rudman

Rudman, W.B., 2001 (Mar 22). Comment on Sea Hares and Inking by Melanie. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Ink glands

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