Flat Rock Crab

Percnon planissimum

Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Family: Percnidae
Genus: Percnon
Species: Percnon planissimum

The flat rock crab (Percnon planissimum) is a very flat, long-legged crab with a dark olive shell and banded legs. Its thin body lets it slip into the narrowest gaps.

It grazes mostly on algae and moves sideways extremely fast when disturbed. It is one of the most common crabs on rocky and coral shorelines.

In the Philippines it lives in the shallows, often under boulders and in crevices around sea urchins.