Hermit Crab

Overview

Hermit Crabs are a frequently mis-housed pet - small crustaceans sold cheaply at beach souvenir shops without adequate care information. With proper care (large humid enclosure, group housing, shell collection) hermit crabs can live for many years: the Caribbean hermit crab has been confirmed at 12. With typical pet-shop housing they usually die within months.

Natural History

Land hermit crabs (Coenobita species) live in coastal tropical regions worldwide. Most pet hermit crabs are wild-caught; captive breeding is rare and difficult.

Common pet species:

• Caribbean Hermit Crab (Coenobita clypeatus) - most common.
• Ecuadorian Hermit Crab (Coenobita compressus).

Appearance

Body 5-15 cm. Tucked into a borrowed snail shell - the crab grows and must move into progressively larger shells throughout life.

Temperament & Handling

Hermit crabs are social and active when properly housed. They are not handling pets - too much handling causes stress and shell drops. Pinches from large hermit crabs can be painful.

Enclosure (Crabitat)

The single biggest factor in hermit crab welfare:

Minimum: at least 10 gallons (38 L) of tank per crab, so 30-50 gallons (114-190 L) for a colony of 3-5; overcrowding leads to aggression and cannibalism. A glass tank holds the heat and humidity; use a secure lid (Wikipedia).

Provide:

• 6+ inch (15+ cm) deep substrate - sand and coco fibre mix that holds tunnels (essential for moulting; hermit crabs bury for weeks).
• Two water dishes - fresh and saltwater, each deep enough for a crab to submerge fully; treat all water to remove chemicals and make the saltwater with a marine-grade salt mix (Wikipedia).
• Climbing structures.
• At least 5 spare shells per crab in graduated sizes.
• Hide caves.

Heating, Humidity, Lighting

• Temperature: a steady 24-30 °C (75-85 °F) (Wikipedia).
• Humidity: 75-85% - essential. Crabs breathe through modified gills that must stay moist, and low humidity slowly suffocates them (Wikipedia). Daily misting and proper substrate help.

Diet

In the wild, the Caribbean hermit crab is a herbivore and scavenger that eats animal and plant remains, overripe fruit and even the droppings of other animals (Wikipedia), so variety matters. In captivity: commercial hermit crab food (no preservatives), fresh fruit and vegetables, raw fish and meat occasionally, and a calcium source (cuttlebone).

Health & Lifespan

Up to 12 years: the Caribbean hermit crab has been confirmed to live that long (Wikipedia); in poor housing they die much sooner.

Common concerns:

• PPS (post-purchase syndrome) - stress from wild-caught + retail conditions; many die soon after purchase.
• Moulting failure - from inadequate substrate or humidity.
• Shell evictions in stressed colonies.
• Mites.

Pros & Cons

Pros: long-lived (with proper care), social, fascinating moulting and shell-changing behaviour, low daily maintenance once set up. Cons: widely mis-housed, sold under false "easy pet" marketing, wild-caught populations declining, not for handling.