January 2012

Wanted: real estate, shell home with an ocean view

Do hermit crabs make their own shell or steal them?

Answer

Hermit crab living in a trumpet shell.
QM image

 While most animals develop or grow their own shell for protection, others are quick to steal these shields to protect themselves. The hermit crab is a great example; they use shells from dead gastropods to live in. As the hermit crab grows bigger and can no longer fit inside its stolen shell, it will start to look for an empty, bigger replacement. The competition is very high for good shells without holes or cracks and hermit crabs will fight each other for the best shell homes.

The hermit crab is not the only animal that uses old shells or other animals for protection. The blue-ringed octopus is commonly found hiding in old shells. This can be a problem for shell collectors as this octopus are very dangerous. Other animals, like the decorator crab, will collect stinging anemones and stick them onto its back and arms for protection from predators.

Queensland Museum's Find out about... is proudly supported by the Thyne Reid Foundation and the Tim Fairfax Family Foundation.