Crosslandia? from Port Stephens

April 16, 1999
From: David & Leanne Atkinson

Hi Bill,

Here is a creature found and photographed by Judy Martin who was diving with is over Easter at Port Stephens [New South Wales, Australia]. The closest we could find was Crosslandia viridis but the colour (brownish green) and spots (bright blue) seem different. It was eating kelp.

David & Leanne Atkinson

Atkinson, D. & L., 1999 (Apr 16) Crosslandia? from Port Stephens. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear David & Leannne,
I am pretty sure this is the brown 'form' of Crosslandia viridis. [See green version at Top of Page] It is certainly an amazing shape. From the side, as in your photo, the edge of the body in front of the large wing-like parapodia, forms a large raised ridge which terminates in the forward projecting rhinophore stalks/pockets.

The shape seems to be a way of camouflaging the animals on the brown algae or green seagrasses on which they are found. Although almost always found on plants, they are not herbivores, feeding instead on hydroid colonies which live on the plants.

Best wishes,
Bill Rudman.

Rudman, W.B., 1999 (Apr 16). Comment on Crosslandia? from Port Stephens by David & Leanne Atkinson. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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