Patagurus rex is a newly described hermit crab from French Polynesia which has forgotten how to equip itself with a shell. Collected at a depth of 400m (1312 feet) at Moorea of the Society Islands, the unusual P. rex didn’t read the manual on how to be a hermit crab and has opted instead to revert to being crab-like with an enlarged carapace serving as its shell.
The idea of a crab evolving to live with a snail’s shell, and then de-volving to grow its own again, is a beautiful reminder that evolution isn’t always a sensible direct line of adaptation from one mode of living to another. The result is a really neat looking hermit crab that probably moves in a very unique fashion now that it doesn’t have a heavy snail shell anymore. [Novataxa]