Hermit Crab

The Australian Land Hermit Crab is native to the tropical and subtropical coastal regions of northern Australia, from the Kimberley across the Northern Territory and through Queensland. They inhabit coastal dune-forests and mangrove edges where fresh water is accessible. They are nocturnal scavengers in the wild.

Hermit crabs are more complex in their needs than their humble appearance suggests. They require both fresh water and saltwater access at all times, high humidity (75-90%), appropriate temperature, sufficient substrate depth for moulting, and the company of other crabs. When these needs are met they can live 10-20+ years. They must always be kept in groups of at least two to three, as they are social colony animals that experience chronic stress in isolation.

Minimum enclosure: 30 x 30 x 30 cm for two small crabs; larger groups need more space. A glass aquarium with a secure but ventilated lid retains humidity while allowing air exchange.

The most critical element is substrate depth. Hermit crabs must be able to burrow completely underground to moult; a minimum of three times the height of your largest hermit crab will give you a guideline to how deep your substrate should be. Maintain this substrate at sandcastle consistency (holds shape when squeezed, does not drip).

Maintain a temperature gradient of 24-28ºC at the warm end using a heat mat or heat lamp on a thermostat. Humidity must be 75-90%: essential for gill function and respiratory health. Mist daily or use an automatic mister. A hygrometer and thermometer must be checked daily. Provide climbing structures and multiple hides. Always keep at least three spare shells per crab, slightly larger than each crab's current shell, in the enclosure.

Hermit crabs are opportunistic omnivores. Offer a wide variety of fresh fruit (apple, mango, banana, papaya, blueberries), fresh vegetables (carrot, sweet potato, leafy greens, corn), dried shrimp, dried mealworms, boiled egg and quality hermit crab pellets. Calcium is critical for moulting: provide crushed cuttlebone or calcium-rich foods at all times.

Food should be available continuously in shallow dishes and replaced daily. Never feed copper sulphate, preservatives, table salt, onion, garlic, avocado, or processed human food. Fresh and saltwater must be provided in separate dishes deep enough for crabs to fully submerge. Use dechlorinated tap water for fresh water; use aquarium marine salt mixed to natural seawater strength (approximately 1.026 specific gravity) for the saltwater dish.

Hermit crabs can be gently picked up but handling should be kept brief and calm. Approach slowly and allow the crab to walk onto the hand voluntarily. Hold close to a surface in case the crab drops: a fall can be fatal. Never pick up by the shell alone as this can cause the crab to detach in panic.

Provide a complex, stimulating enclosure: varied climbing structures at different heights, multiple hides, burrowing areas of different substrate depths, and the water dishes for bathing. Shell selection enrichment is particularly meaningful: a diverse collection of empty shells of varying shapes and sizes allows crabs to evaluate, try on and select preferred shells. Crabs engage in elaborate shell-swapping activities. Offering a wide variety of safe foods daily provides foraging enrichment.

Post-moult death: The most common serious cause of death. Caused by disturbance of a moulting crab, insufficient substrate depth, low humidity during moulting, or calcium deficiency. Prevent by ensuring 15-20 cm substrate depth, maintaining 75-90% humidity and never digging up buried crabs.

Dehydration and gill damage: Low humidity causes irreversible gill damage; maintain humidity consistently.

Copper toxicity: Tap water with copper sulphate is toxic; always use dechlorinated water.

Stress and isolation: Hermit crabs kept alone experience chronic stress; always keep in groups of at least two to three.