Spurilla australis from Port Phillip Bay, Australia

June 22, 2006
From: Perry Davis

Dear Bill,
I found this nudibranch at low tide in very shallow water on flattend seagrass in Swan Bay, Victoria on the15 june 2006. It was a cloudy day and this 30 mm creature was active. Hope you can identify it for me!

Locality: seagrass beds, 200ml, Swan Bay, Bellarine Peninsula, Port Philip Bay, Victoria. Australia, tidal bay, 15 June 2006, intertidal seagrass bed. Length: 30mm. Photographer: Perry A Davis.

Perry Davis


Davis, P.A., 2006 (Jun 22) Spurilla australis from Port Phillip Bay, Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16890

Dear Perry,
This is Spurilla australis which we often think of as a warm-water, if not tropical, Australian species, but it seems to be found all around mainland Australia. Have a look at the species Fact Sheet for information on the biology of this fascinatingsolar-powered nudibranch. It is able to grow single-celled plants in its digestive system and take advantage of their ability to photosynthesise sunlight into sugars.

In your photos you can see how this solar-powered species has modified its body to assist its 'horticultural' activities. Firstly, its cerata, which are usually cylindrical in aeolids, have become flattened and leaf-like, to provide more sunlit surfaces for the captive plants. You will also see a dark brown network inside the cerata. This network is the highly branched digestive gland, in which the plants [zooxanthellae] are nurtured. Most aeolids have just a single duct in each ceras, but in these solar-powered animals, every extra branch provides an extra place for more plants.   
Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Jun 22). Comment on Spurilla australis from Port Phillip Bay, Australia by Perry Davis. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16890


Spurilla australis

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