Roboastra gracilis mating ritual
April 16, 2005
From: Karen Willshaw
Hi Bill,
Greetings from the sandbar in the middle of the Indian Ocean - aka Cocos (Keeling) Islands. These two Roboastra gracilis were caught in the act. I do apologise for the clarity of the images, it was the best I could do at the time.
Locality: Cocos (Keeling) Islands, Australian Indian Ocean Territories. Indian Ocean. Depth: 14 metres. Length: 4 mm. 10 April 2005. rocky substrate & sand. Photographer: Karen Willshaw.
Karen Willshaw
karen@IkanImages.com
Willshaw, K., 2005 (Apr 16) Roboastra gracilis mating ritual. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/13503Thanks Karen,
I have often wondered if this species, which feeds on other nudibranchs, is partial to cannibalism. If so, it would make mating a dangerous pastime - as some spiders discover. I have included a close-up of the skin of one of your animals as it shows the nature of the yellow spots and lines on this species very well. You can clearly see a thin line across the yellow. This is a crack or opening to a deep fold or groove in each of these yellow regions, and the skin is highly glandular exuding a yellowish viscous secretion when the animal is disturbed. Species of Tambja and Nembrotha have similar glandular pits or grooves disguised as coloured lines.
Best wishes,
Bill Rudman
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