Land Hermit Crab (Coenobita clypeatus)
All hermit crabs live in a shell that they carry on their back like a snail. Unlike snails, hermit crabs do not produce their own shell, they use an old shell made by another animal, such as a marine snail. Hermit crabs have soft bodies, so they need their shell for protection, and have adapted a hook-shaped tail and strong legs to hang on to the inside of their shell. The hermit crab can retreat completely into the shell when threatened. When the hermit crab grows too big for its shell, it will search for a bigger one and crawl quickly out of its small shell and into the new one.
Land Hermit Crabs (Coenobita clypeatus) are the biggest hermit crabs in Bermuda, growing up to 10 cm (4 inches) long, and they are the only hermit crabs found on land. Both of these factors limit the shells that they can use. Therefore like other Bermudians, the land hermit crabs have been facing a housing crisis.
The main source of shells for the Land Hermit Crab was another resident of the rocky shoreline - the West Indian Topshell. These large snails were a favourite food of the early settlers and were extirpated from Bermuda. With large shells no longer available, the number of crabs that could survive here was quite small. The crabs survived by using fossil Topshells and occasionally other shells or human garbage for shelter.
The West Indian Topshell was reintroduced to Bermuda in 1982 and was given legal protection from harvesting. With Topshells becoming common on the South Shore once again, it is hoped that the new supply of shells will ease the hermit crab housing shortage and the population of these threatened crabs may begin to increase.
Not only are they dependant on the sea as a source of shells for new homes, but the Land Hermit Crab is also dependant on the sea for reproduction. The female goes down to the sea once a year just before the full moon to release her fertilised eggs which burst open when they are released into seawater. The young crab emerges and drifts with the plankton.
Land Hermit Crabs eat all kinds of plants, and can often be found climbing high up in coastal trees. They are also part of nature’s clean up and recycling service, as they scavenge rotting animals and dead fish.
The Land Hermit Crab is native to Bermuda; it is also found in Florida and the Caribbean. Its habitats include mangrove forests, salt marshes and coastal forest. Locally, the Land Hermit Crab is found in the mangroves in several places in St. George’s and on the South Shore at several rocky coastal sites in Devonshire and Paget. The largest population is found on the shore next to the Hungry Bay Mangrove Swamp. They are often found hiding under coastal vegetation, under rock ledges or in holes in trees where herons and other predators cannot find them.
These crabs are easy to identify when found. They have large claws and hairy legs that are red and purple and come out of the front of the shell.
The Land Hermit Crab is now rare in Bermuda. As mentioned, this is partly due to a lack of suitable shells. Land Hermit Crab numbers have also been reduced by habitat loss as mangrove habitats and coastal areas have been cleared and developed, or damaged by hurricanes.