Legs banded in orange and white, walking around inside a borrowed cone shell - the most conspicuous hermit crab on the reef and one of the fussiest about its housing.
Most hermit crabs take whatever rounded snail shell fits. This one is built flat, and it specializes in the narrow slot-shaped opening of cone shells, which excludes almost every competitor and almost every predator that would need to reach in after it. The trade-off is that its choice of homes is limited to the shells of a single family, and a growing crab that cannot find the next size up has nowhere to go.
Shells are the constraint on every hermit crab's life. They cannot make their own, they have to inherit them from dead snails, and a shortage of the right sizes limits populations directly. Where hermits find a newly empty shell they queue by size and swap in sequence, each crab moving into the one just vacated.
It works at night over rubble, cleaning up detritus, algae and carrion. Harmless, decorative, and worth remembering when you pick up an empty shell to take home: somebody is waiting for it.
- legs banded bright orange-red and white, unmistakable under a torch
- flattened body, adapted to narrow cone-shaped shells
- usually carrying a cone shell rather than a rounded snail shell
- length up to 5 cm
