Watch: Carrier Crab Uses Spiny Urchin As Shield
March 24, 2017 - Watch a carrier crab live up to its name by carrying a sea urchin on its back for protection. Carrier crabs have specially modified back legs that can grasp onto objects ranging from pieces of shells to debris to living creatures like sea urchins. The sea urchin's spines help ward off predators that may try to eat the crab. In exchange, the sea urchin gains access to new feeding grounds.