Greenmark Hermit Crab

Biology/Natural History: This species is common in the Puget Sound region but most are so small they are assumed to be juveniles of other species such as P. hirsutiusculus.

Rocky or sandy, exposed or sheltered

Depth Range: Mostly subtidal to 126 m, occasionally intertidal in cold waters on outer coast.

The carapace of this small hermit crab is smooth, the lateral parts are covered with soft setat, and only part of it is calcified. Eyescales have no deep median furrow, and their base is not covered by the carapace. Leg 4 is subchelate. Abdomen coiled, right cheliped is nearly as long as the walking legs and its carpus is longer than wide. The left cheliped is smaller than right but similar in structure. Both chelipeds are greenish-brown and gray, often with orange tips. The merus of both chelipeds is brown and gray with a dull white or yellowish distal band. The merus of the chelipeds often have orange-tipped spines. Dactyls of legs 2-3 not twisted. The carpus of the right second pereopod is serrated. Dorsal surface of propodus of left chela with neither a prominent ridge or crest nor a concavity. Ventral surface of merus of right cheliped with 1or 2 prominent tubercles. Chelae with irregular rows of stout spines along with long tufted setae. Antenna 2 reddish brown without white spots. Has a white band at the articulation of dactyl and propodus on legs 2 & 3. Carapace length to 1 cm. Carapace is light gray and cream with lengthwise purple stripes, each of which has light dots. The abdomen is purple and gray.

How to Distinguish from Similar Species: P. hirsutiusculus also has 1 prominent tubercle on the ventral surface of the merus of the right cheliped and white bands between the propodus and dactyl on legs 2-3 but the tubercle is often obscure plus the chelae have closely spaced tubercles & granules instead of spines. Its second antennae are green with white spots. Pagurus hemphilli has orange-red antenna 2 and no white band between the propodus and dactyl of legs 2-3.

Geographical Range: Port Gravina, Alaska to Los Angeles