The coconut crab (Birgus latro) is the largest terrestrial arthropod and is in the same family as the terrestrial hermit crab. They live near the ocean but prefer dense forest cover. These crabs have adapted to breathing on land with their unique organ called branchiostegal lung. This lung has tissue that is similar to tissues found in gills but absorbs air instead of water. They are omniverous and feed on fallen fruit and coconut palms. Coconut crabs have a keen sense of smell and use it to hunt food. They flick their antennae to locate smells of rotting fruit or carcasses. Coconut crabs have no known predators besides other coconut crabs and people. These crabs are hunted for their meat. In 1981, the coconut crabs was listed as a Vulnerable Species on the IUCN Redlist, but has since been listed as data deficient.
This picture was taken from Wikipedia.