These crabs use empty snail shells to protect their soft abdomen. They hold onto the shell with tiny modified legs. They have one large chelae (claw) and that is used as a door to protect the crab when it retreats into its shell.
They are found from the low tide zone to depths of 15m.
They are scavengers and use their chelae to sort through sand to find food particles.
There are ~34 species of Hermit Crab in NZ (& even 9 terrestrial or land living ones!). The marine species share many characteristics.