We see them everywhere down here in the Caribbean. Most of us pay little attention to them but if one takes the time to watch for awhile, they’re quite fascinating. Lumbering along with their homes on their backs, they are undeterred by barriers that seem insurmountable to our observations.
And unfortunately they are often taken for the pet trade, ultimately dying from abuse and ignorance—for they require precise humidity and salinity in their environments. My first experience with a Hermit Crab pet trader occurred on the island of Roatan some years ago. A Texan dressed as a pirate complete with an eye patch covering a completely healthy eye was the first clue that this Texan did not have both oars in the water. I wondered why he was collecting commercial-sized jars from the kitchen each day ‘til the reason became evident the last night of his stay. He had been filling the jars all week with Hermit Crabs which also explained why the activities director was unable to find usually plentiful Hermit Crabs for the once-weekly crab races.
At the farewell party, the pirate was bragging about the number of Hermit Crabs he’d captured that week and loudly proclaimed how much money he’d make when he returned home in spite of a very high mortality rate. After friends prevented me from flying across the table to keel-haul the pirate, the activities director and I came up with a rescue plan. The pirate was a thirsty fellow so we made sure he had an endless supply of beverages and we slipped away to his cabana. Unfortunately, many of the Hermit Crabs were dead or dying but those who were still viable found their way out of the jars and back to the wild. And, the following day, just in case we missed a few, we notified the security guards at the airport who proceeded to thoroughly search the pirate’s luggage and person, much to his dismay.
While there are approximately 500 species of Hermit Crabs, both land and marine species, some growing as large as a coconut, one of the most commonly known is the Caribbean Hermit Crab (Coenobita clypeatus). An adult Caribbean Hermit Crab can measure up to 2” in length although their small size is often enhanced by the rather large sea shells they carry.
While not true crabs, Hermits are crustaceans with 10 legs including four walking legs, four smaller holding legs keeping them firmly entrenched in their seashell homes, a small pincher for feeding, and a very large pincher for defense. Thousands of years ago they were given the name Hermit Crab when the Greeks likened them to the religious men living alone in small shelters in the desert; eremos pronounced “hairmos”, meaning desert in Greek.
Living up to 30 years in the wild, Caribbean Hermit Crabs are classified as a land species although their very existence is dependent upon the sea. Also known as tree crabs, soldier crabs, and purple pinchers due to the often purplish colored large pincher, they can be found throughout the Caribbean from Venezuela to Florida. Like all Hermit Crabs, the Caribbean species has a soft, banana shaped abdomen that they protect by living in sea shells and, occasionally, land snail shells. Generally moving into empty shells, they will sometimes evict a small animal from its shell.
Since Hermit Crabs have exoskeletons (external) they must molt as they grow, shedding their outgrown external skeleton. When young they may molt as often as every month or so but once adults, molting may only take place every 18 months. But, when they molt they also become larger and must seek a larger shell in which to reside.
Prior to molting, Hermit Crabs eat enough to hold them for a molting process that may take up to three months as adults. They also take in sea water for the salt that aids in shedding the old exoskeleton and they add fresh water to their shells to sustain them during the molting process which begins with the crab digging a burrow in the ground.
Once underground the old exoskeleton is shed, lost limbs are regenerated, and the shed exoskeleton is eaten for its mineral content. When the crab emerges it begins a desperate search for a new shell for they cannot survive long otherwise. Although shells are the desired target, frantic Hermit Crabs have been known to take up temporary residence in small bottles.
Usually taking an abandoned shell, Hermit Crabs will also trade shells with another if each determines the trade is beneficial. And, occasionally, forcible evictions take place with the crab having the largest defense claw most always the winner. The desired size of the shell sought seems to be dependent upon the size of the large pincher; the opening of the shell no larger than the largest pincher that is used as a ‘door’ to block the opening.
While the Caribbean Hermit Crab lives on land and breathes air, they have gills rather than lungs. Breathing through gills on land requires they live in humid environments and maintain water within their shell homes to keep the gills moist.
Mating takes place on land however the female Hermit Crab must return to the sea to deposit her eggs where the salt water triggers hatching. The young remain in the sea while their gills develop the unusual ability to breathe air and they find their first shell homes. If we look closely at the small shells lying along the shoreline we can often find tiny Caribbean Hermit Crabs within.