Hermit crabs are essential scavengers in the ocean. They may crawl into discarded tires looking for food or shelter, and become trapped and die of starvation. Humberto Ramirez via Getty Images Every ...

What is a hermit crab? There are over 800 species of hermit crabs worldwide, and almost all are ocean dwellers—though people are likely most familiar with the dozen semi-terrestrial species, called ...