World’s largest land crabs tracked using GPS

Washington: 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 meter), 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, according to the new study. They mainly move between the island’s inland rainforest and the coast. Males, previously thought to remain in the forest, were instead found to migrate toward the ocean as females do, possibly to drink the saltwater, which they prefer over freshwater. The researchers also played a prank on the crabs, carrying them in an opaque bag up to 0.6 miles (1 kilometer) from their home territory. If released along their migratory route, the crabs could usually find their way home, the first demonstration of long-distance homing behavior in land crabs, according to the study. Released outside of this path, however, the crabs became lost, and never returned “home.” The study was published this week in the journal PLoS ONE. ANI