Geograpsus grayi
Japanese Name: カクレイワガニ
Chinese Name: 格雷陸方蟹、葛氏陸方蟹
English Name: Little Nipper Crab
Origin: Widely distributed from the western Pacific to the Indian Ocean and eastern coast of Africa
Among the crabs in the family Grapsidae, the genus Geograpsus shows a relatively high degree of terrestrial adaptation. These land crabs store water in their body and extract oxygen through their gills. Sometimes they mix mucus with water and blow bubbles to expose the water to air, enhancing gas exchange. Thanks to their highly efficient gills, Geograpsus grayi can live hundreds of meters inland, away from marine predators, often in forested areas.
The carapace width reaches about 5 cm. The body is a vivid deep purple, making it one of the most striking terrestrial crabs. Females migrate to the shore during high tide after sunset in June and July to release their larvae in the surf. Exhausted individuals are sometimes found on the beach after spawning.
