Crustaceans

Coconut Crab: The Land Giant That Hunts Birds

Coconut crabs crack coconuts with 742 pounds of force, a claim scientists doubted for a century. In 2016 a biologist watched one hunt and kill a seabird.

Barnacle: The Animal With the Longest Penis for Its Size

Darwin spent eight years studying barnacles. Their penises can reach eight times body length, and a parasitic relative turns male crabs into surrogate mothers.

Woodlouse: The Crustacean With Copper Blood and Bacteria That Rewrite Its Sex

It looks like an insect, but a woodlouse is a crustacean with blue copper-based blood and, in some species, bacteria that turn genetic males into egg-laying females.