Purple Shore Crab
Scientific Name: Hemigrapsus nudus
Category: other
Brief Description
A small, common crab found in the rocky intertidal zones of the Pacific coast, known for its square-shaped carapace and often dark purple or reddish coloration.
Characteristics
Features a smooth, somewhat square carapace up to 5 cm wide. It typically has purple, reddish, or dark green coloring with small purple spots on the claws (chelipeds). The legs lack the hairy tufts found on similar species.
Habitat
Low to mid-intertidal zones, typically hiding under rocks, in crevices, or among seaweed.
When to Find It
Visible year-round, best observed during low tide.
Conservation Status
Common/Stable
Ecological Role
Serves as both a predator of small invertebrates and a primary food source for shorebirds, gulls, and larger predatory fish and octopuses.
Easily Confused With
Hairy Shore Crab (Hemigrapsus oregonensis) which has hair-like setae on its legs and lacks the purple spots on its claws.
Observation Tips
Gently lift rocks in the intertidal zone of Puget Sound during low tide. Always return rocks to their original position to protect the habitat.
Interesting Facts
Unlike many other crabs, the Purple Shore Crab can survive for long periods out of water as long as its gills remain moist, allowing it to forage high on the shoreline.
User Notes
Puget Sound WA