January 25, 2007
From: Leanne & David Atkinson
Okenia purpurata and Okenia vena are still at Halifax Sponge Gardens. Here are some photos of Okenia purpurata and Okenia vena 'pairs' in the Amathia tortuosa. Not sure what they were doing other than competing perhaps for the same piece of food.
Locality: Halifax Sponge Gardens, Marine Reserve, Port Stephens, 13 metres, New South Wales, Australia, Pacific, 21 January 2007, Sandy bottom with scattered sponges, soft corals, ascidians, bryozoans and hydroids.. Length: approximately 2 to 3 mm. Photographer: Leanne & David Atkinson.
Leanne & David Atkinson
email@example.comAtkinson, L. & D., 2007 (Jan 25) Okenia purpurata & Okenia vena together. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19300
Dear Leanne & David,
Finding two different species together like this does raise interesting questions. There is no sign of matng. It is possible that they have eaten most of the zooids in the bryozoan colony and are fighting over the last scraps, but it may be that they are following each mucus trails. I suspect that the chemical difference in the mucus of closely related species is not that great, so it could be a common mistake for them to follow each others trail. This would be a mistake if they had mating in mind, but it would also be a useful way to find food - since they both feed on the same bryozoan.