Hermit crabs are found both on land and in the water. Whether they are land or marine crabs, they are crustaceans that live in a shell discarded by another animal. This article discusses the peculiarities of “land” or “tree” hermit crabs, not the oceanic varieties.
They actually start life as fish and grow up to become terrestrial life. These little crabs start out in the ocean, just like marine hermit crabs. While in the water as babies, hermit crabs start out as larvae called zoeae and develop into aquatic crabs, swimming and breathing underwater through gills. As adults, they can no longer breathe underwater, but they still breathe through gills that must be kept moist to prevent suffocation. Adult hermit crabs have lost the ability to swim.
The shape of its tail is determined by its first shell. The back of a hermit crab curves to fit and cling to the shell it lives in. The shape of their first shell is very important and will influence shell selection for the rest of their lives.
They “go number one” under their eyes. Hermit crabs excrete urine through glands at the base of their antennae. Which means they “pee” on your face.
His name is a misnomer. Although these animals are commonly called “hermit crabs”, they are not actually true crabs because they lack a hard shell on their abdomens, and they are not hermits because they live in large groups of about a hundred crabs in the wild.
Hermit crabs have been bred in captivity, but this is not where pet stores come from. All available pet stocks were collected from beaches around the world where these animals are native. Most domestic hermit crabs in the US come from the western Atlantic coasts.
They don’t have vocal cords, but they still “talk.” These cute little crustaceans make squeaky sounds by rubbing their feet together. This is called “stridular” and works similar to the noise you get when you rub your two hands together. They can be very expressive.
They move. In order to grow, this crustacean has to go through a process of burying itself, shedding its old exoskeleton, eating it, and resurfacing. This is called molting, and it can all take weeks. Without a safe place to bury itself for weeks, about once or twice a year, a hermit crab will die.
Only six of its ten legs are usually visible. Although hermit crabs have ten legs like a spider, they keep the back four inside their shells to anchor them and keep the inside of the shell clean.
The legs can be “thrown away” without killing the crab. If a crab is stressed or frightened, it may “drop” a leg to distract a threat and hopefully escape. Sometimes they also do this when they are sick. They will grow a new leg back in the next few molts.
Hermits poop. Their owners sometimes wonder if they do, because crab poop is small and gets mixed in with bedding materials. These guys poop inside their shell and then take it out or pull it out of the side of their shell.
“Hermies” have long been adored as short-term pets that are easy to care for. They can actually live up to 30 years in captivity if cared for correctly. Pet stores routinely provide poor pet care for hermit crabs and pass poor pet care information to owners, resulting in a short lifespan. Like a much misunderstood pet, they have a large following of devotees online who dole out good care information.