You can find three species of hermit crab on Christmas Island’s beaches: the red hermit crab (Coenobita perlatus), purple hermit crab (Coenobita brevimanus) and tawny hermit crab (Coenobita rugosus).

Closely related to our iconic robber crabs, hermit crabs only grow to a few centimetres and have a soft, curved abdomen that they protect by living in an empty seashell. They use their four rear legs to anchor themselves inside the shell.

As a hermit crabs grows, it needs to keep moving into larger shells, and will often try on several different shells to find the best fit.

On Christmas Island they usually use the shells of sea snails. Purple hermit crabs, which travel quite a distance inland, may also use the shells of the introduced giant African land snail.​