Aplysia juliana eaten by Flatworm

April 10, 2006
From: Lisa Kirkendale

Hi Bill,

I thought you would be interested in these aqarium observations of a flatworm which ate an Aplysia in our aquarium recently. It fortunately did it on the side of the tank so I was able to take these photos through the glass. Following the Aplysia sp., the flatworm then proceeded to eat a specimen of Chelidonura inornata (unfortunately I didn't get any good pictures of that). The animals were all collected locally around Sydney [NSW, Australia].

A friend of mine, Raphael Ritson-Williams has tentatively identified the flatworm as Paraplanocera oligoglena. We were both grad students at the University of Guam Marine Lab, and he has recently published on a flatworm in Guam which harbours the neurotoxin, tetrodotoxin.  The planocerid he was looking at ate a variety of marine snails from at least 11 families, and also a species of Elysia.

  • Ritson-Williams, R., Yotsu-Yamashita, M. & Paul, V.J. (2006) Ecological functions of tetrodotoxin in a deadly polyclad flatworm. Proceedings of the National Academy of Sciences (PNAS), 103(9): 3176-3179.

Sincerely,
Lisa Kirkendale

fragum4ever@yahoo.com

Kirkendale, L, 2006 (Apr 10) Aplysia juliana eaten by Flatworm. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16272

Thanks Lisa,
This is an interesting observation. Its common knowledge that flatworms are carnivorous but actually catching them in the act is not that easy. Its certainly not a good week for Sea Hares as its only a day or so since we posted the message about Aplysia californica being eaten by Navanax [message #16251]. Although not an expert on flatworms I have been using Paraplanocera oligoglena for this animal [see Fact Sheet], on the advice of Leslie Newman. I am pretty sure the sea hare is a small Aplysia juliana which may explain why it did not excrete any purple ink in its distress.

For those not familiar with flatworm anatomy, these animals have a 'mouth' on the underside of the body so essentially they can catch their prey by walking over the top of them and sucking them in.

Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Apr 10). Comment on Aplysia juliana eaten by Flatworm by Lisa Kirkendale. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16272

Factsheet

Aplysia juliana

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