Mictyris longicarpus, the light-blue soldier crab, is a species of crab that live on sandy beaches from the Bay of Bengal to Australia; with often members of the genus Mictyis, it is "one of the most loved crabs in Australian". Adults are 25 mm (1 in) across, white, with blue on their backs, and hold their claws vertically. They feed on detritus in the sand, leaving rounded pellets of discarded sand behind them. The males may from into large "armies" which traverse the beach at low tide, before the crabs dig into the sand to wait for the next low tide. Mictyris longicarpus is nearly spherical, with an upright body. Its carapace is powder blue, with the rest of the body being white except for purple patches on the joints of the legs. The chelae (claws) are slim and curve downwards, and are held vertically in front of the crab. Given the crab's upright posture, the eyestalks are short. The body is up to 25 mm (0.98 in) across, or "about the size of a cherry". Mictyris longicarpus is found from Singapore and the Bay of Bengal to New Caledonia and Australia, reaching as far south as Perth, Western Australia in the west, and around the coast of Queensland and New South Wales to Wilsons Promontory, Victoria.