Xenia Swimming Crab

Caphyra loevis

Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Family: Portunidae
Genus: Caphyra
Species: Caphyra loevis

The Xenia swimming crab (Caphyra loevis) is a tiny swimming crab that lives inside pulsing Xenia soft corals and decorates itself with their polyps. Covered in pieces of its host, it is almost impossible to see until it moves.

It is usually under 1-2 cm across. Although it belongs to the swimming crab family and has paddle-shaped rear legs, it spends its life within one soft coral colony, feeding on the coral and on particles in the water while using its host as shelter and camouflage.

Xenia soft corals are common on reefs in the Philippines, and patient divers who look closely among the pulsing polyps can sometimes find this crab hiding in plain sight.

Photo: Kai Squires, CC BY 4.0, via iNaturalist