Pre-mating Ritual - Chelidonura amoena

June 7, 2006
From: Mike Krampf

I thought I'd share this pic of Chelidonura amoena with you. It's the first time I've ever seen two sea slugs in a ball like this and a ID book I have describe this as a "pre-mating ritual". I thought it was very unique so I thought I'd share it with you.

Locality: Hatano Point, 30 feet, Miri, Sarawak, Malaysia, South China Sea, 27 May 2006, Patch Reef. Length: 3-4 cm. Photographer: Mike Krampf.

PS. I just found your site and think it's awesome!

Cheers,
Mike

 

mtkrampf@yahoo.com

Krampf, M., 2006 (Jun 7) Pre-mating Ritual - Chelidonura amoena. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16792

Dear Mike,
Have a look at the message reporting on a breeding aggregation of C. punctata [#16512]. I am pretty sure in your photo that the two Chelidonura are mating. In the copy of your photo alongside I have added a white triangle to represent the penis of the upper animal, which sits on the right side of the head. The female genital opening is at the back on the right side, under the parapodial flap - just about where the point of the white triangle is. These animals are hermaphrodites, with a fully functional male and female reproductive system, so in your photo, the upper animal is acting as male and the lower one as female. I suspect the lower animal is also trying to act as a male as well, and if he/she can get into the right position there is no functional reason why he/she can't act as both simultaneously.

True nudibranchs almost always act as both male and female simultaneously when they mate [see message #16116] but they are built a bit differently with all their reproductive organs together at one spot on the right side of the body. 
Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Jun 7). Comment on Pre-mating Ritual - Chelidonura amoena by Mike Krampf. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16792

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Chelidonura amoena

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