Re: Sea Hares - attack & defence

April 21, 1998
From: P.M. Johnson

Dear Dr. Rudman,

Thank you very much for your quick reply to my questions. Thanks also for the reference list, there was one (Fiorito et. al., 1985) that I was not aware of and that could be very helpful to me. There is another reference that you might want to add to the list:

Nolen, T.G.; Johnson, P.M.; Kicklighter, C.E.; Capo, T. (1995): Ink secretion by the marine snail Aplysia californica enhances its ability to escape from a natural predator. J. Comp. Physiol. A 176, 239-254.

This paper came out of my undergraduate senior thesis at the University of Miami, so I can send you a reprint if you like.

I have several of your papers on opisthobranchs, in most of which you discuss the various mantle glands of different species. It's been suggested by several authors that the ink gland of the Aplysiomorpha was derived from the hypobranchial gland. I was wondering what you're thoughts are on this and also if you know of any possible precursors to the opaline gland as well.

Thanks again for your help,


P.M. Johnson.

Johnson, P.M., 1998 (Apr 21) Re: Sea Hares - attack & defence. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

It is very hard to find evidence to show whether mantle cavity organs in one group are homologous (that is have the same evolutionary origin) with organs in other less closely related groups. There has been a burst of activity in studying the evolutionary relationship of gastropod molluscs over the last decade and although this work has been a great step forward it also shows us how much we still have to learn. A good reference to this work is W.F.Ponder & D.R.Lindberg, 1997. Towards a phylogeny of gastropod molluscs: an analysis using morphological characters. Zoological Journal of the Linnean Society: 119, 83-265. We can make guesses about the origins of these glands, and there are similar glands in other primitive opisthobranchs such as the aglajiids, but it is just as likely that they evolved independently in each evolutionary line. To me, of greater interest is what is the function of these organs? and why do some species of Aplysia not have a purple gland? ...Bill Rudman.

Rudman, W.B., 1998 (Apr 21). Comment on Re: Sea Hares - attack & defence by P.M. Johnson. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Ink glands

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