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Tree-climbing Crab

© Rina Abdul Jamal

It looks like it could eat you. Thank goodness its primary diet is coconut. Among the Chamorro people in Guam, it is known as Ayuyu. Commonly known as the robber crab or the coconut crab, the tree-climbing crab is the largest land invertebrate. Adult coconut crabs can grow about 1 meter (40 inches) from head to tail and weigh about 17 kg (37 pounds).

Found in the southwest Pacific and Indian Oceans, the coconut crab is a type of hermit crab. Unlike other hermit crabs, this huge crab, has developed a sense comfort on land. In fact, it is so comfortable living on land, it has developed a skill to climb trees to get to its favourite food and believe it or not, it will even drown if submerged under water even for a few minutes. With that said, it is important to mention that it still breathes through gills. Its modified gills are surrounded with spongy tissues and to keep the gills moist, it will dip its legs into the water and pass or swipe them over the gills. It is also interesting to note that the coconut crab still needs to drink seawater from time to time to maintain the salt level.

The coconut crab apparently got its name from its favourite food, the coconut. It will pry open any split coconuts, crack them open and drill the eye of the coconut with its powerful claws. Its other common name, which is the robber crab, explains an interesting habit possessed by this crab. The crab has been known to be attracted to shiny items and has the habit of stealing them!

Birgus latro or the coconut crab is a slow-growing and slow-maturing crab. It will take about 4-8 years before it can reproduce. After mating on land, the female will store the eggs under its tail or abdomen for a few months and will then deposit the fertilized eggs into the sea. Once hatched, the tiny larvae look nothing like their parents. They will float around for 4-5 weeks before gradually developing their own shell and moving away from the sea.

Adult coconut crabs usually have an established burrow. They will usually come out at night in search of food. However, in some areas where there are a lot of coconut crabs around, they will also emerge during the day probably to compete with others and get more food.

Because of its size, an adult coconut crab does not have natural predators except for humans. It is often considered a delicacy. One interesting way of catching one of these crabs is to place a patch of grass on a palm tree, which is already occupied by a crab. When the crab climbs down and feels the grass, it will loose its grip thinking that it has reached the ground. Before it realizes that it has been tricked, it slams on the ground and stuns itself.

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