Surfing on a turtle’s tail makes swinging crabs monogamous

Surfing the world’s oceans on the back of a turtle may sound like a life of luxury, but for a small crab it also means restricting itself to a single mate.

A species of small oceanic crab, Planes minutus often makes its home on the shells of loggerhead turtles. They tuck themselves into a tiny space above the turtle’s tail and below the shell, just the right size for a pair of crabs – a male and a female living in a simple monogamous relationship.

But these crabs will also make their homes on floating debris, where they nestle among stalked barnacles, and often enjoy a more swinging, polyamorous lifestyle. Read more in New Scientist.