A porcelain crab (Petrolisthes militaris) collected from the Montebello Islands (photo: Andrew Hosie).

Porcelain crab

Petrolisthes militaris

This porcelain crab is one of the most abundant crabs on tropical Australian reefs. They characteristically flattened body helps this crab to squeeze into tight spaces between bits of coral rubble and stones. Porcelain crabs are filter feeders and have large feathery mouthparts for collecting food from the water column. The large claws are therefore used defensively, but are more likely to be autotomised (fall off) to distract predators, much in the same way a lizards tail is.

Morphology

Dorso-ventrally flattened body, claws with distinct sculpturing and often a fringe of 'hair' along anterior margin.

Evolution

The porcelain crabs are not true crabs, but are the result of an independent but convergent evolutionary lineage more closely related to hermit crabs.

Behaviour

Porcelain crabs are shy creatures, and will very quickly retreat from threats. They can use their abdomens to swim backwards by rapidly flicking it, much like a shrimnp would.

Habitat

Marine

Shallow water, <30 m. found in reef habitats typically in rubble.

Distribution

Indo-West Pacific

Taxonomy

Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Subclass: Eumalacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Anomura
Superfamily: Galatheoidea
Family: Porcellanidae
Genus: Petrolisthes
Species: militaris
Name Published Year: 1862
Scientific Name Authorship: Heller
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/Petrolisthes-militaris
Accessed 20 Sep 2024

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