Petrolisthes eriomerus is a species of marine porcelain crab found in the eastern Pacific Ocean.

The chelipeds are armed with claws usually of similar size which are half as long again as the length of the carpus and disproportionally large.

[3][4] This crab is found on the shore and at depths of up to 90 metres (300 ft) on the western coast of North America from California to Alaska.

It prefers areas with strong currents and can be found under rocks, especially those embedded in sand or shingle, among seaweed and in beds of mussels on both exposed and sheltered coasts.

[4] Like other porcelain crabs, P. eriomerus sometimes casts off limbs as a diversion when trying to escape from a predator, a process known as autotomy.