Hermit crabs are neither reptiles nor amphibians; they actually belong to the class of animals known as crustaceans. This means they are more closely related to lobsters and shrimp than to reptiles or amphibians.
Crustaceans are characterized by having an exoskeleton, jointed limbs, and a segmented body. Hermit crabs, in particular, are known for their unique habit of living in discarded shells, which they use for protection as they grow. They require a moist environment to survive, as they breathe through gills that must remain wet, which is a characteristic often associated with amphibians. However, unlike amphibians, hermit crabs do not undergo a complex life cycle involving metamorphosis and do not have a life stage that is exclusively aquatic.
In summary, while hermit crabs do share some habitat similarities with amphibians, they are classified as crustaceans and belong to a different group of animals altogether.