The Halloween Crab, Gecarcinus quadratus, and the Rainbow Crab, Cardisoma armatum, are very similar creatures. They have many names, which include Indigo Crab, Land Crab, Moon Crab, Patriot Crab, and Tricolor Crab. They are relatively small animals; the largest grows up to 15-20 centimeters across the carapace (the exoskeleton). They are very colorful, with an indigo-colored back, orange legs, bright lavender pinchers, and a white underbelly.
The Rainbow Crab can be found in the costal areas of West Africa, and in the lower Volta river system. The Halloween Crab lives on the banks of rivers in rainforests in Central America and Costa Rica. These crabs live in the sand or mud on banks of rivers, or on the beach. It likes to burrow, though any dark place is appropriate. Consequentially, these crabs like both fresh and salt water. They are also amphibious, meaning that they live in both water and on land.
In captivity, the aquarium should provide a land environment and water. Sand would make a great substrate, because itís perfect for burrowing. Rocks are acceptable as well, although an additional place to hide will be required, such as a hollowed-out log that you can find at any pet store. The crabs need a place to sit out of the water; a slope is suggested to re-create the beach or riverbank environment. To prevent the sand from sliding down the slope and evening out, place a dam on the shallowest end, such as a piece of bogwood or some rocks. The water will need to be kept clean, whether changed frequently for a bowl, or a filter for the sloping environment. These crabs need heat warmer than room temperature, so a heat rock or a warm heating pad underneath the sand and water will work. The temperature should stay around 22C.
Halloween Crabs eat just about anything that washes up on the shore, so it can be fed accordingly, with foods including vegetables, fish, hermit crab food, fish flakes, and dead insects (crickets). This food can be provided in a small dish, or just placed on the land portion of its environment. Cuttle fish bone, when nibbled, will provide an excellent source of calcium for the crab. Uneaten food should be removed as soon as possible, as these crabs dislike rotten or foul food.
Halloween Crabs can be territorial and aggressive, so the aquarium should be larger the more animals that are going to be housed. One crab might bully another, so one should be careful if housing more than one. Also, care should be taken when picking up or moving the crab, as oneís fingers can be pinched. If a crab is picked up, it will make clicking noises.
Halloween Crabs will try to eat any fish kept in the same habitat, so if pet fish are planned, it is wise to keep them in a separate aquarium than the crab. Breeding has not been successfully completed in captivity, though the crabs will need a vast amount of water and space. The female releases many eggs, which live as plankton for a month. They eat very small bits of food they can find in the waterís edge.
Halloween Crabs that are for sale have been caught from the wild, and will be available according to season. Males are more expensive than females because of their more vibrant color. Also, because so few of these creatures are caught at a time, their price tends to be on the expensive side.