The land hermit crab, Coenobita clypeatus, can enliven your classroom and create tremendous interest, without requiring extensive care. This animal is a useful tool in a number of social behavior studies: aggression behavior, shell exchange, and feeding behavior; all of which can be conducted easily within the confines of the classroom.
Land hermit crabs, such as C. clypeatus, are found in tropical and subtropical regions of the Caribbean, their northernmost range being the Florida Keys. They are most often found in beach areas near the ocean but may travel about a kilometer inland. Land hermit crabs are excellent climbers and, as scavengers, eat both plant and animal matter.
These animals are nocturnal, usually hiding under leaves or burying themselves in the sand during the heat of the day. This activity seems to be directly related to the sun’s heat. They usually show activity in the classroom terrarium. Their gentle and timid disposition make them great pets as well, because they rarely pinch. C. clypeatus grows slowly, and may live as long as ten years in captivity.
Land hermit crabs are best kept in a large, dry container (terrarium or aquarium tank) with at least 4– 8” of clean sand, gravel, or wood shavings on the bottom. A small piece of driftwood can be provided so the crabs can climb, and a cover for the container should be provided to prevent the animals from escaping. A small dish of fresh, clean water should be placed in the terrarium and should be available at all times. Make sure that the water dish is shallow, because land hermit crabs will drown if left immersed in water for several hours. However, the crabs do carry a small supply of water in their shells to allow them to travel to locales where water is unavailable. In order to keep them healthy, they should be misted daily with water from a spray bottle. You should also add dry moss or crumpled paper to one side of the container for them to burrow under, especially when they are molting. The terrarium should be kept between 15 – 29°C (59 – 84°F). If the temperature drops below 18°C (64°F) the crabs will become inactive, and at temperatures below 10°C (50°F) they will die. In order to maintain the temperature, place a 25 W light bulb over the container to generate enough heat on cold winter nights.
Crabs eat nearly any food offered, including dry dog food, pieces of fruit, lettuce, and cookies, although a vegetable diet is preferred. Hermit crabs should have a ready supply of food available at all times, so refill their food dish when it gets low, or replace the old food when it goes bad if you’ve given them fresh fruit or vegetables. WARD’S also offers a specially formulated hermit crab food (88 W 0612) that will supply them with all the necessary nutrition.
As the crab grows, it will need to change to a larger “home” or shell. Several shells of different sizes should be kept in the container so the crab may exchange its shell whenever necessary. Any spiral gastropod shell will do for this purpose. Also, when hermit crabs molt, they will need a source of calcium to assist in the hardening of the new exoskeleton. To meet this need, simply place a few pieces of egg shell in the terrarium.
This guide is also available in PDF format on wardsci.com.
