Image of bluespine hermit crab

Description:

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 The hermit had withdrawn completely out of sight within the sponge.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