About Macrophthalmus pacificus Dana, 1851
Macrophthalmus pacificus Dana, 1851 is a species of sentinel crab. It is widely distributed across the Indo-West Pacific Ocean, with recorded locations including India, Japan, Malaysia, New Guinea, the Solomon Islands, and northern Australia. Within Australia, it occurs along the northern coast, ranging from northern New South Wales to the area around Exmouth in Western Australia. This species inhabits muddy substrates in low-tide tidal zones of mangrove forests adjacent to river mouths. It is commonly found feeding in shallow still water and on soft mud. Adult males have sky blue claws, and the dactyl (upper claw) of males bears a tooth. Like all other species in the genus Macrophthalmus, male M. pacificus have larger claws than females. Its carapace is smooth and shiny, and reaches a maximum width of approximately 25 mm. Macrophthalmus bicarinatus is a recognized synonym of Macrophthalmus pacificus.
