Placida cf. dendritica from Sydney

March 23, 2000
From: Stephanie Clark

Dear Bill

The small sacoglosans were found on Shark Island, Sydney Harbour, on Codium, on the 26 Oct 1999. The specimens as quite small about 3-4mm. However, I watched the individuals in the photo using a hypodermic needle type copulation method. With one individual basicly stabbing the other any where it likely in mostly in the lower part of the animal around the 'tail' region. From what I could see the needle part of the copulation structure was not barbed in any way but looked just like a small needle.


Clark, S., 2000 (Mar 23) Placida cf. dendritica from Sydney. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Stephanie,
Thanks for the observations. I think this is what we are calling Placida dendritica. New Zealand animals of this species have been reported to mate by hypodermic insemination of sperm into their partner but usually near the position of the enclosed sperm sac. Random injection anywhere on the body has been reported in a couple of species of Elysia but not for stiligerids. It is possible that your animals are immature animals just 'practising' or that they are perhaps another species.

Best wishes,
Bill Rudman.

Rudman, W.B., 2000 (Mar 23). Comment on Placida cf. dendritica from Sydney by Stephanie Clark. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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