Dorsal view of the decorator crab (Camposcia retusa) (Photo: Andrew Hosie)

Decorator crab

Camposcia retusa

Camposcia retusa is one of many species of decorator crabs, but it should win the prize for decoration. This small (body up to 3 cm) and long-legged crab is generaly completely covered in algae, sponges and other sessile organisms, making it very hard to spot.

Morphology

The carapace is tear-dropped shaped, and body and legs are covered in hooked hairs that act like velcro to attach other organisms to its body. Chelipes are slender and smooth, adapted to snip and place decoration on the body and are generally the only part left uncovered. Eyestalks are long and slender.

Evolution

There is only one species in this genus.

Behaviour

Camposcia retusa is a slow-moving crab, commonly found covered in algae, sponges and debris, but it will also attach most sessile organisms (such as ascidians and byozoans). Most attachements are carefully snipped off and placed so they will keep living and growing on the crab, maintaining the disguise. It is also believed that the decorating habit has a function of repelling predators (when covered in distasteful sponges) and food storage. As with most decorators crabs, it is believed that the colours on the chelipeds compensate for the lack of visual cues from the rest of the body-necessary for communication between individuals of the same species (for mating and agonistic displays).

Method of reproduction

Sexual

Habitat

Marine

Found in shallow waters, on coral rubble and seagrass areas.

Distribution

Indo-West Pacific including Red Sea

Taxonomy

Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Subclass: Eumalacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Brachyura
Superfamily: Majoidea
Family: Inachidae
Genus: Camposcia
Species: retusa
Name Published Year: 1829
Scientific Name Authorship: Latreille
Commercial Impact: 

This species is targeted by the aquarium trade

Conservation Assessment: Least Concern

Net Conservation Benefits Fund

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

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