Self mutilation in sea slugs

January 20, 2003
From: V. Patel

Dear Bill,
Sea slugs are considered to the most remarkable example of self mutilation and I would be very grateful if you could recommend any usuful literature.
V. Patel

Dear V. Patel,
'Self-mutilation' is a peculiarly human activity. By definition it requires a knowledge of 'self' and is a prpduct of a very troubled mind. Many animals however, have evolved the ability to drop or break off parts of their body, but as their bodies are designed to do this, I hardly think we should call it 'mutilation'. I remember many years ago there was a controversy in New Zealand about whether it was cruel to cut the tails off living crayfish [lobsters]. The Minister of Fisheries got up in Parliament and said we, and presumably the lobsters, had nothing to worry about, as his experts had told him that joint-legged animals like crayfish had evolved to drop off limbs like this in a process called autonomy and it didn't hurt them a bit!

The process is called autotomy, not autonomy, and although the lizard's tail is an example of it, the poor lobster's tail is not. Have a look at the autotomy page on the Forum for some opisthobranch examples. Not all peculiarities in body shape are the result of autotomy. Have a look at the Abnormalities page for a growing list of strange abnormalities caused by accidental damage or developmental problems.
Best wishes,
Bill Rudman

Rudman, W.B., 2003 (Jan 20). Comment on Self mutilation in sea slugs by V. Patel. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from