Coconut crab  (Birgus latro)

This species is a type of land hermit crab with a spectacular appearance and intriguing biology. It is probably the largest terrestrial arthropod in the world and is able to grow to relatively gigantic proportions (2). Unlike most other hermit crabs, only the very small juveniles of this species find and use gastropod shells to protect their soft-skinned abdomen as they develop. Larger juveniles abandon the shell-carrying habit, and instead their abdomen develops a hard skin, the exoskeleton, as over the rest of the body (3). This protects the crab, reduces water loss and does not restrict its growth, allowing it to reach up to a metre in size toe-to-toe (2). This huge crustacean is well adapted to life on land with long strong legs. It also has large muscular claws which are used for husking coconuts and opening the shell to eat the flesh (3). This is a unique behaviour amongst crabs and explains why this species is called the coconut crab. The claws are in fact so powerful they can lift objects such as vegetation or rocks weighing up to 28 kilograms (4). Its stalked eyes are red, and this crab's body colour varies between islands from purplish-blue to orange-red (5). Studies show that males are considerably larger than females (2).