Found throughout the tropical Indo-West Pacific.
Coffs Harbour Region, northern New South Wales, Australia, December 1990. PHOTO: Bill Rudman.
Formerly known as Trippa osseosa. See message
Atagema osseosa is an example of how many nudibranchs have evolved to perfectly match their surroundings. This species has the same colour and texture as the sandy sponge on which it lives and feeds. There are also a series of darker markings (patches without spicules) which match the oscula or waterholes in the sponge.
• Kelaart, E.F. (1858). Description of new and little known species of Ceylon nudibranchiate molluscs and zoophytes. Journal of the Ceylon Branch of the Royal Asiatic Society,
Columbo, 3(1): 84-139.
Rudman, W.B., 1998 (October 14) Atagema osseosa (Kelaart, 1859). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/triposse
September 11, 2006
From: Julie Marshall
Concerning message #15535:
Attached are a couple more images of Atagema osseosa. This animal was 10 mm in size and was found beneath a dead coral slab at the reef crest at Heron Island [Great Barrier Reef] at low tide.
Locality: Heron Island, Intertidal, Queensland, Australia, Pacific, 15 November 2001, Intertidal. Length: 10 mm. Photographer: Julie Marshall.
Marshall, J.G., 2006 (Sep 11) Re: Atagema osseosa from sthn Queensland, Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/17436
Juveniles like this are very good at showing how the spicules in the mantle wall form a radiating network within the mantle tissue, creating a skeletal framework for both the tubercles and the mantle wall.
August 9, 2006
From: Gary Cobb
In January, I went to Alex Headland and turned over some rocks and found this beautiful little dorid. I think it is Atagema osseosa. When I initially found it I thought it was a lamellariid. I collected it and while it was crawling I knew it was a dorid.
Locality: Alexandra Headland, sthn Queensland Australia. Locality: Depth: intertidal. Length: 24 mm.11 January 2006. Photographer: Gary Cobb
Cobb, G., 2006 (Aug 9) Atagema osseosa from sthn Queensland, Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/15535
Thanks for the nice photos. They show the tubercles, with a crown of spicules around the tip, very well. For those of you not familiar with the term, these tubercles are known as caryophyllidia.