Ceratosoma trilobatum from the Dampier Archipelago, WA (Photo: Nerida Wilson/Lisa Kirkendale)

Three horned Ceratosoma

Ceratosoma trilobatum

Up to 11 cm. This is a variable and brightly colored nudibranch that is common in intertidal and subtidal environments. Although this species shows considerable colour variation, in northwestern Australia there appears to be a unique colour variant in which the background pattern is uniform or only slightly patched, and the edge of the mantle and the foot is often white.

Morphology

It is characterised by having only one large lateral lobe on each side of the body, just anterior to the gills. There is usually a ridge joining each lateral lobe to the anterior head lobe. The background colour can vary from pale green to orange-red or brown, usually, but not always, mottled and spotted with lighter colours. There are usually small yellow or orange spots and the edge of the mantle, and sometimes the foot, is bordered with a broken or continuous purple line.

Evolution

Little is known about the relationship of this species to other members of the genus.

Behaviour

Most species of Ceratosoma have a long recurved dorsal 'horn' which acts as a defensive lure attracting potential predators to the part of the animal which contains most of the distasteful chemicals stored from their food (Rudman, 1991).

Method of reproduction

Sexual, hermaphrodites

Habitat

Marine

Distribution

This is a widespread Indo-west Pacific species. In Australia, it is known from approximately the Northwest Cape, Western Australia to Queensland.

Taxonomy

Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Heterobranchia
Order: Nudibranchia
Suborder: Euctenidiacea
Infraorder: Doridacea
Superfamily: Doridoidea
Family: Chromodorididae
Genus: Ceratosoma
Species: trilobatum
Name Published Year: 1827
Scientific Name Authorship: J.E. Gray
Commercial Impact: 

None

Conservation Assessment: Least Concern

Net Conservation Benefits Fund

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Western Australian Museum Collections https://museum.wa.gov.au/online-collections/names/ceratosoma-trilobatum
Accessed 31 Aug 2023

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