Pagurus Fabricius 1775

In this view one can see that the carpus of the right cheliped is about twice as long as wide, and also can see the white band around the distal end of the merus of the cheliped.

The dactyls of legs 2 and 3 are not twisted.

hermit crab

The chelae are covered with setae and blue or white tubercles, but there is no prominent ridge on the dorsal surface of the left chela.

hermit crab

The merus of the right cheliped has no prominent tubercles on the ventral side.

Here is a ventral view of another individual, also showing the lack of prominent tubercles on the ventralmerus of the right cheliped.

As with most hermit crabs, the abdomen is soft and curved. The male has uropods on the end of the abdomen.

Leg (pereopod) 4 is much smaller than the other legs, and subchelate.

Sometimes this species lives in a sponge, probably Suberites suberea. I cut this sponge open (the hermit crab is still alive but anesthetized). Before I cut it open, the sponge was alive and actively pumping water out of the osculum visible on the top of the lower piece. The hermit had withdrawn completely out of sight within the sponge. The cavity in the sponge was smooth and coiled like a snail, though I could find no trace of a snail shell. I sliced through the "body whorl" cavity (lower cross-section), then again about 1 cm to the right side the cavity curled (upper cross-section). The hermit crab was far back in the second whorl as shown, anchored even farther in with its uropods. I was able to remove the hermit crab from its position above only with difficulty. Photo by Dave Cowles, July 2005

This individual has clumps of white, bristly setae onthe eyestalks and on the antennae, though the individual above did not. Photo by Dave Cowles, July 2008

Pagurus kennerlyi from 100 m depth, San Juan Channel. Animal is encased in a sponge (Suberites sp?). (Photo by: Dave Cowles, July 2000)

In this side view the slight coiling of the "house" is seen. The house is made of the hydroid Hydractinia milleri. The egglike structures are gonozooids of the hydroid. The hermit crab gives no sign of being stung by the hydroid. Some other species of hermit crabs, known to be symbiotic with Hydractinia, also do not seem to be vulnerable to their sting while some other hermit crab species are.

This dorsal view of the head shows the smooth carapace, the lack of tufts (setae) on the dorsal margin of the cornea, and the fully exposed eyescales with a single terminal spine and no median dorsal furrow.

The carpus of the left chela is longer than the merus. The carpus of the right chela is about 1 1/2 times as long as wide and is not extremely flattened (the carpus is the last segment visible on the right chela here, as the propodus and dactyl are folded underneath as the animal crawls along). The merus of both chelae has a prominent white band on the terminal end.

The 2nd and 3rd dactyls are not striped, do not have ventral spines, and are not obviously twisted in relation to the propodus. This is a view of the merus (top right, spiny), carpus (spiny), propodus, and dactyl of the right second leg.

This ventral view of the right cheliped shows that the ventral side of the merus (to the left of the sharp turn, or "knee") does not have any prominent tubercles.

This X-ray view of the above live animal shows that there is a small gastropod shell at the base of the Hydractinia house. The shell is about 5 mm long. Digital X-ray compliments of Julie Kellogg, DDS and Tietan Dental Clinic.

Pagurus dalli, from about 20 m depth at Mukilteo. The "shell" on its back is composed mostly of a colony of Hydractinia milleri hydroids. (Photo by: Dave Cowles)

Another view of the animal, partly out of the shell. The carapace shield is clearly visible. Notice also how the dactyl of the walking legs twists slightly in relation to the propodus.

This view of the underside shows that few spines are found on those surfaces. Note that the animal is in a moon snail shell, which is the characteristic choice of this species.

Pagurus armatus found at about 20 m depth in Admiralty Bay, Whidbey Island. (Photo by: Dave Cowles, August 2011)