What is a Coconut Crab?

The coconut crab is a monstrous crab that reaches sizes unheard of among other arthropods. Found on islands in the Indo-Pacific Ocean, it was one of the species recorded by Charles Darwin on his legendary expeditions. Specimens can easily reach up to 3 feet (1 m) in diameter and weigh as much as 11 pounds (5 kg), with the females being considerably smaller than males.

Actually a type of hermit crab much like the tiny ones kept as pets, the adult coconut crab does not share other hermit crabs' habit of using a series of shells as armored, mobile homes. Instead, the body of the coconut crab itself develops into a hard, shell-like coating, which does not limit growth and allows it to reach its massive size. The name coconut crab comes from the crab's ability to crack open and eat coconuts with its strong claws. Pressure from the claws can move or pick up objects as heavy as 60 pounds (28 kg). The coconut crab can be a variety of colors from red to purple to blue; color depends on what island it is from.

For most of their lives, these crabs live along the coastlines of the islands they inhabit. During breeding season, crabs head into the jungle in order to mate. Afterward, the female heads out into the sea to lay her eggs. There, the eggs quickly hatch and remain in the water until the young crabs grow legs and mature enough to make it to land.

Young coconut crabs use shells for protection, much like their smaller relatives, but they stop using them when they are between two and three years old. A coconut crab reaches breeding age around five years of age, and during this time it regularly sheds its hard, outer exoskeleton as it grows. It stops growing when it is about 40 years old, but can live for decades beyond that.

Coconut crabs are also unique because while they breathe with the help of gills that must be kept damp, they can also drown in water. Better suited to life on land, they almost always remain in close near the sea, where eggs are released. A largely nocturnal creature, they can easily travel with their strong legs and powerful claws, and spend the day hiding in rock shelters or dead trees.

Viewed by many as a curiosity, coconut crabs have been threatened by the arrival of tourists and the development of a food industry to supply consumers who consider them a delicacy and, in some places, an aphrodisiac. Expanding cities and the establishment of tourism-related developments have intruded on the crabs' natural habitats, and they are preyed on by some animals introduced by human visitors to their islands. While some islands maintain thriving populations, the strain is clearly visible on the crabs that inhabit other islands.

Coconut crabs are the largest terrestrial arthropods in the world, native to islands across the Indian Ocean and parts of the Pacific Ocean. They are renowned for their impressive size, with some individuals weighing up to 9 pounds and measuring up to 3 feet from leg to leg. These land-dwelling crabs are a keystone species in their ecosystems, playing a crucial role in nutrient recycling.

Despite their name, coconut crabs have a varied diet. They are omnivores, feeding primarily on fruits, nuts, seeds, and the pith of fallen trees. They are also known to eat carrion and other organic matter, including the shells of other crabs to obtain calcium. Occasionally, they have been observed climbing trees to harvest coconuts, which they break open with their powerful claws.

Coconut crabs have a remarkably long lifespan for invertebrates, living up to 60 years. Their longevity is attributed to their slow growth rate and the absence of natural predators in their adult stage. This extended lifespan allows them to reach their impressive size, as they continue to grow throughout their lives.

Coconut crabs are considered a species of concern due to habitat loss and human predation. They are particularly vulnerable because of their slow reproductive rate and the fact that they are considered a delicacy in many cultures. Conservation efforts are in place in some regions to protect these unique creatures and their habitats.

Yes, coconut crabs are adept climbers, using their strong legs and hooked claws to scale trees. This ability allows them to access coconuts and other fruits as food sources. They are known to climb up to 6 meters high to forage, and they sometimes use trees for shelter during the day.

Coconut crabs mate on land, but the female releases her fertilized eggs into the ocean, where they hatch as planktonic larvae. After a period of several weeks, the larvae settle on the ocean floor and metamorphose into a hermit crab-like form, using empty shells for protection. As they grow, they transition to a terrestrial lifestyle and develop their characteristic robust exoskeleton.