December 17, 2002
From: Nishina Masayoshi
To accompany my other photos, here are photos of the close-up of the rhinophores. I agree with your opinion that "the 'rings' on the rhinophores seem to be a series of radiating papillae rather than a solid plate. However the don't seem so clear in some of the other photos,"
The rhinophores rings in these photos are rather wavy. I suspect that the radiating papillae shaped 'rings' are because of some damage or on the way of regrow? or just a variation? This animal often found on the reddish coral. So I suspect it's the their diet.
All photos by M. Nishina on Hachijo Island.
Date: 7 Dec, 2002. Size: 6mm-8mm
The structure of the rhinophore plates is a bit difficult to determine from the photos but does seem to be quite variable. In the top photo there seems to be a posterior notch or break in the plate, while in the lower left photo there seems to be a very wavy edge as you describe. Concerning its food. I would be surprised if it was eating the coral, but it is possible that there is a hydroid that is growing in association with the coral and appears as single red polyps, on a short stalk, scattered over the coral colony.
Cratena affinis? from South Africa
From: Colin Ogden, October 26, 2006
Re: Cratena cf. affinis from Japan
From: Nishina Masayoshi, December 4, 2002
Cratena affinis from The Japan Sea
From: Shigeru Hayashi, July 27, 2002
Cratena affinis from Hachijo Is., Japan
From: Rie Nakano , July 13, 2002