Commensal Porcelain Crab

Polyonyx transversus

Systematics: Anomura Family Porcellanidae

Distinguishing Characters:
The shiny carapace is oval, much wider than long, about 12 mm wide. The long chelipeds have twisted claws at the end. Although the animal is basically dull orange it appears very muddy.

Habitat and Distribution:
The commensal porcelain crab lives on the floor of muddy bays across southern Australia from Queensland to Perth but is not known from Tasmania.

General Biology:
This species is often found in the bottom of the papery tubes of a species of polychaete worm or in the siphons of bivalve molluscs. What benefit the crab gets from these associations is not understood but the behaviour does allow them to survive in what would otherwise be a very dirty environment.

Feedback and queries should be sent to the Discovery Centre at Museum Victoria.
Please note, the Discovery Centre can help you only with questions about crustaceans from southeastern Australia. It can not advise on the care of pet hermit crabs or on crustaceans from other regions.