When you read or see about hermit crabs you always think of the tiny and cute critters that crawls around the beaches and eat peacefully with their little claws.
But don’t be mistaken, there is a hermit crab species that are HUGE. By huge, we mean huge that can eat big animals. Scary right?
Meet the Coconut Crab also known as the ‘robber crab’ or ‘palm thief’. Coconut crabs are known to be the largest terrestrial arthropod in the world. They can weigh up to 4.1 kgs or 9.0 lbs and the can grow up to 1m (3 ft 3 in) in length from each tip to tip of the leg. So we’re not exaggerating on the huge part there.
Coconut crabs are mostly found in the following: islands across the Indian Ocean, parts of the Pacific Ocean, Gambier islands, and Pitcairn Islands. They also live off the coast of Africa near Zanzibar.
Just like the smaller hermit crabs, coconut crabs use empty shells from other sea snails as well for protection. Smaller hermit crabs use their gills to breathe, coconut crabs breathe through their organs known as branchiostegal lungs. And for that, they will drown if they are immersed in water for too long.
Diet
A Coconut crabs’ diet mainly consists of fleshy fruits, nuts, drupes, and seeds. However, they are omnivores and will eat other animals as well and even dead animals. There are even sightings that coconut crabs hunting and eating a Polynesian rat. Back in 2016, there’s also a coconut crab seen climbing a tree where a red-footed booby was nesting and the large coconut crab hunted and ate it.
They also eat coconut flesh, they can climb a coconut tree up to 10 m or 33ft high. They will fall intentionally to the ground after getting the coconut from the tree since coconut crabs can survive a fall (unhurt, I tell you) of at least 4.5m or 15ft.
Once the coconut is in the ground, they will cut holes into the coconuts using their claws. But do note it’s not a quick process since it will take them days to fully open a coconut.
Habitat
Coconut crabs are the most adapted decapod living in the land. As mentioned before, they will drown in sea water if they are immersed for too long. So where can you find them? They live mostly in burrows and rock crevices. Just like small hermit crabs, they dig their own burrows as well in sand or in loose soil.
They are nocturnal creatures as well. During day-time, coconut crabs stays hidden away from the heat to reduce the loss of water caused by the heat. They use strong fibers from coconut husks as bedding on their burrow. Coconut crabs will close the entrance from their burrows when they are about to rest, the reason for this is to create moist within the burrow which will be beneficial for their breathing.
Same with the smaller hermit crabs, the only time they return to the sea is when they are about to release their eggs since their egg needs to be in contact with salt sea water to hatch.
Human Predation, Nearing Extinction, and Conservation
There are no known predators of coconut crabs, but it is known that some humans hunt them for food due to their quality of their meat and size. But they are only hunted on an island with a human population. Their meat is known to be eaten as a delicacy and even as an aphrodisiac on some islands. And because of these reasons, they are threatened by humans.
Coconut crabs have become endangered due to the following reasons: habitat loss and predation by humans. But conservation strategies were already put in place to protect them from human predation, like in Guam and Federated States of Micronesia, it is banned to capture and consume egg bearing female coconut crabs. While in Northern Mariana Islands, it is prohibited to hunt non-egg-bearing adult coconut crabs. Humans are only allowed to hunt them on the following months: September, October, and November. And you can only hunt them if you have a license to do so.