The Coconut Crab – the World’s Biggest Land Arthropod

How the Coconut Crab Lives

The Coconut crab, which scientists call Birgus latro, is the largest land-living arthropod in the world – in fact it’s the largest of all the invertebrates that live on land! It has a body length of up to 40cm (15 inches) and it weighs up to 4.1kg (9 lb) and a leg span of more than 90 cm (1 yard). The males are generally bigger than the females. Coconut Crab
The Coconut Crab is the World’s Biggest Land Arthropod
They can live more than 30 years. Their body is divided into a front section which has 10 legs, and an abdomen. The frontmost pair of legs has large claws which the crab uses to crack coconuts – that’s how it got its name. These claws can lift objects up to 29 kg (64 lb). The next two pairs of legs are large, powerful walking legs which enable the coconut crabs to climb vertically up trees like coconut palms. The fourth pair of legs is smaller with pincers like a pair of tweezers at the end. It is used by young crabs to grip the inside of a coconut husk to carry  for protection. Adult coconut crabs use this pair for walking and climbing. The last pair of legs is very small and it is use to clean the breathing organs. These legs are usually held inside the cavity containing the breathing organs.

The coconut crab  is sometimes called the Robber Crab or Palm Thief because some say the crabs like to steal shiny items such as pots and silverware from houses and tents. It can be found in tropical islands of the Indian and Pacific Oceans.

Coconut Crabs are Hermit Crabs

Coconut Crab Climbing a Tree
The Coconut Crab Climbing a Coconut Tree

Coconut crabs are a kind of hermit crab – most hermit crabs have a soft abdomen, and use snail shells to protect themselves. However, the Coconut Crab is so large that there are no snail shells big enough! Only young Coconut Crabs use snail shells. As they grow older, they use bits of coconut shell, and when fully grown, their abdoment gets harder and they don’t use anything at all. Hermit crabs are not really crabs at all, but belong to a group of crustaceans of their very own. This group is included, with crabs and lobsters, into a larger group of crustaceans called Decapods (which means “10-footed”). So, as well as being the biggest land arthropod, coconut crabs are

  • The world’s biggest land crustacean,
  • The world’s biggest land decapod
    crustacean and
  • The world’s biggest hermit crab!

Coconut Crab Diet

The coconut crab cannot swim. They use a special lung to breathe. They have an excellent sense of smell and are able to detect smell from a distance. The smell of rotting meat, bananas, and coconuts, all potential dinner, catch their attention especially. Apart from coconuts, the crabs also eat fruit and a range of other organic material, including leaves, dead animals and the shells of other creatures.

Coconut Crab Life Cycle

The female coconut crab releases the eggs into the ocean at high tide. The crab larvae will float in the ocean for about 28 days. After this larval stage they will lose their ability to breathe in water. The young coconut crabs are quite flexible. About four to eight years after hatching, the coconut crab matures and can lay eggs.

People and Coconut Crabs

Meat from coconut crabs is considered a delicacy by Pacific islanders. It taste similar to lobster and crab meat. The coconut crab can be boiled, steamed or cooked in coconut milk. However, the meat is sometimes toxic, if the crab has made a habit of eating poisonous plants. Not surprisingly, claws that can crack coconuts can also give a painful pinch to an incautious person – and the crab may continue to hold on tightly to its victim. Some people say that rubbing the crab tummy may cause it to loosen its grip – but it’s certainly better not to let the crab bite you in the first place!

Coconut Crabs are sometimes kept as pets, for example in Japan, especially when they are not fully grown. But you will definitely need a sturdy cage that they cannot dismantle with their powerful claws.

The numbers of Coconut crabs many places has gone down, and they’ve even died out completely in some places. This is because people have hunted them too much and destroyed the places they live. Now, the Coconut Crab is a world-wide protected species.

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