According to the Seattle Aquarium, there are over 500 different species of hermit crabs around the world. In spite of what their name implies, hermit crabs are not solitary animals and can usually be found in groups of a hundred or more in the wild.
The land hermit crab is sometimes called the purple pincher crab or the soldier crab. This crab gets its name from its purple pinchers. These are fresh-water crabs and one of the most common crabs sold in pet stores. Hermit crabs prefer to move around at night because they are nocturnal by nature. They live between 1 and 10 years in the wild and can grow between 1 and 4 inches long.