Hermit crabs are crustaceans that inhabit discarded shells for protection. They do not produce their own shells, relying instead on finding empty gastropod shells.
Homes in the Wild
Hermit crabs inhabit diverse global environments, categorized as land or aquatic species. Land hermit crabs (family Coenobitidae) reside in tropical and subtropical regions. They are found along coastlines, venturing into forests and mangroves, but remain close to the ocean for moisture and shell access. These terrestrial species burrow into moist sand or leaf litter to escape predators and regulate body temperature.
Aquatic hermit crabs (family Paguridae) occupy marine environments from shallow tide pools to deeper ocean floors. Many thrive in intertidal zones, among rocky shores, or on sandy and muddy bottoms, foraging for food. Some are also found in coral reefs, using complex structures for shelter. Their natural habitats provide resources for foraging, molting, and finding suitable shells.
Their Essential Mobile Homes
The abandoned gastropod shell is integral to a hermit crab’s anatomy and survival. It protects their soft, asymmetrical abdomen from predators, desiccation, and injury. The shell also helps maintain internal moisture, important for land hermit crabs that breathe through gills. Without a properly fitting shell, a hermit crab is vulnerable to environmental stressors and predation.
As hermit crabs grow, they must periodically exchange their current shell for a larger one. This process, often following a molt, requires locating and assessing new shells for size, weight, and structural integrity. The availability of diverse, appropriately sized shells is important for their growth. A lack of suitable shells can lead to competition, stress, and even death, as crabs may be forced to occupy ill-fitting or damaged shells.
Life as a Pet
Many encounter hermit crabs as pets. The most common types are land hermit crabs, primarily species like the Caribbean hermit crab (Coenobita clypeatus) and the Ecuadorian hermit crab (Coenobita compressus). Keeping these animals in captivity involves providing an artificial habitat that replicates their wild conditions, meeting their needs for health and longevity.
Pet hermit crabs rely on human caregivers for a suitable living space. They cannot forage for diverse food sources or seek new shells. Proper husbandry practices are important for their welfare, including creating an environment that supports natural behaviors like burrowing and climbing.
Designing a Proper Captive Habitat
A proper captive habitat for hermit crabs replicates their natural coastal and forest environments. A deep substrate (ideally 6 inches or more) of play sand and coco fiber allows for burrowing and molting. High humidity (70-80%) is maintained through misting or a humidifier, important for gill respiration. Habitat temperatures should consistently range from 75°F to 85°F, often requiring a heat mat on the tank’s side or back.
Both fresh and saltwater dishes, deep enough for full submersion, are necessary for hydration and gill health. Freshwater should be dechlorinated, and saltwater made with marine-grade salt. A variety of appropriately sized, clean, empty shells should always be available for hermit crabs as they grow. These elements support their physical and behavioral needs in captivity.