Chromodoris westraliensis is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of very colourful sea slug

Slug

Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...

, a dorid nudibranch, a marine

Marine (ocean)

Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

 gastropod mollusc in the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Chromodorididae

Chromodorididae

Chromodorididae are a taxonomic family of medium-sized to large, colorful, sea slugs; dorid nudibranchs in the superfamily Doridoidea. These are marine gastropod mollusks....

.

Distribution

This species of nudibranch occurs in coastal regions of Western Australia

Western Australia

Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

, from the Kimberley region in the north of the state, to its southern occurrence near Esperance

Esperance, Western Australia

Esperance is a large town in the Goldfields-Esperance region of Western Australia, located on the Southern Ocean coastline approximately east-southeast of the state capital, Perth. The shire of Esperance is home to 9,536 people as of the 2006 census, its major industries are tourism, agriculture,...

. It is the most abundant nudibranch of the Perth region.

Life habits

These nudibranchs feed on sponges, usually a single species, storing the toxins the sponge contains, in order to deter their own potential predators.

This species occurs in shallow waters on partially exposed reefs and at depths up to 18 metres.

Description

The length of this animal is up to 400 millimetres. A mantle covers the upper parts of the animal and extends to form a skirt at the sides. The colouring is two (or one) bright blue patches on a black background, with an orange outline. This aposematic coloration advertises its toxicity to would-be predators.

Two sensory organs, tentacle shaped rhinophore

Rhinophore

A rhinophore is one of a pair of club-shaped structures which are the most prominent part of the external head anatomy of a group of sea slugs, marine gastropod opisthobranch mollusks in the order Nudibranchia, the nudibranchs, specifically the dorid nudibranchs.- Etymology :The name relates to the...

s, are orange, and are located at the upper surface of the head. The gills, clustered and plumose, are also orange and arranged near the anus.