Granular Claw Crab (Oedignathus inermis)

Description: Granular claw crabs are a pear-shaped crab that appears purplish-brown in color. As its name suggests, this crab is covered in little bumps all over its body, especially on its much larger right-hand claw. The carapace, or shell, grows to be about 4 centimeters in width. On their undersides, the abdomen of this crab is thick and soft.

Habitat: Granular claw crabs are found along the coastline of Japan and along North America’s coastline from Alaska to central California. They prefer to live in the middle intertidal zone in very sheltered spaces, like between rocks in crevices, inside shells (pictured), between giant green anemones, and underneath mussel beds or algae.

Diet: In the wild, they feed by straining plankton from the water, and one of their natural predators includes the black oystercatcher, which is a bird commonly found at Haystack Rock. 

Tide Pool Tidbits:

• Oftentimes, granular claw crabs can be found in pairs. 

• The granular claw crab is actually a Lithodid crab; this means that it has three pairs of walking legs and a fourth pair of legs that is either reduced in size or completely absent.

References: Central Coast Biodiversity, Walla Walla University