Atagema osseosa
(Kelaart, 1859)

Suborder: DORIDINA
Family: Dorididae


Found throughout the tropical Indo-West Pacific.


Coffs Harbour Region, northern New South Wales, Australia, December 1990. PHOTO: Bill Rudman.


Defensive coloration in sea slugs

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.

Authorship details
Rudman, W.B., 1998 (October 14) Atagema osseosa (Kelaart, 1859). [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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