Using GPS technology, scientists have tracked 55 huge robber crabs on Christmas Island, south of Indonesia.

They found that these land crabs, which have a leg span of up to 3.3 feet (1 metre), typically stay within a small home range, living in crevices or between tree roots.

Crabs are arthropods, an enormous group of animals defined by their exoskeletons; the group includes insects, arachnids and crustaceans.

The crabs can also travel more than two miles in search of water, food and mates, says a new study.