New Scientist
Image: Vanessa Pike-Russell
Some hermit crabs have unusually large penises, and now we might know why. A long penis allows a male crab to have sex without leaving the shell he calls home, reducing the risk it will be stolen while he is busy.
Many species of hermit crabs protect themselves from predators by moving into empty mollusc shells, which they then carry around with them. Mark Laidre at Dartmouth College, New Hampshire, calls the mollusc shells a form of hermit crab private property.
A few hermit crab species – especially those in a group called the Coenobita – modify their private property: spending months or even years tearing away some of hard material inside the shell to make it a roomier and more comfortable dwelling. But remodelled shells are potentially seen as more desirable, which can make them a tempting target for theft by another hermit crab especially when the homeowner is preoccupied. Laidre wondered whether this risk of theft might explain a curious feature of Coenobita hermit crab anatomy – namely, that some males have penises that can be 60 per cent as long as the rest of their bodies. Read more on newscientist.com…
