greenish black underwater crab over sand - marine life at andaman & nicobar islands, india

andaman aquatic arthropod arthropoda attractive beach biology bioscience black brachyura coast coastal crab creature crustacean dark decapoda fauna food geology gray grey havelock havelok hevlok india indian island islands legged life mangrove marine marsh mud muddy nicobar ocean oceanic oceanography oceanology ocypodidae organism pattern portunid portunidae salt sand sandy science seafood seashore shore swamp swimming terrestrial tropical underwater water