Macrophthalmus crassipes

Macrophthalmus crassipes is a species of sentinel crab in the family Macrophthalmidae, found around China, Thailand, Malaysia, Australia, and the Caroline Islands.^[1] In Australia it is found from north Western Australia through to New South Wales.^[1] Common names include the seagrass sentinel crab^[2] and the orange spined sentinel crab. On adult males there is a substantial tooth on the lower claw and a much smaller tooth on the upper claw, and noticeable orange spines on the “wrist” (carpus) of the clawed leg and on the palm of the clawed leg.^[1] The carapace is covered in small granules, and is up to around 37 mm (1.5 in) across.^[3][4] It is a burrowing crab, and lives in open tidal flats, muddy or with sandy mud, low on tidal creek banks, and adjacent mangroves.^[1]

Seagrass sentinel crab
On Nudgee Beach, Queensland
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Malacostraca
Order:	Decapoda
Suborder:	Pleocyemata
Infraorder:	Brachyura
Family:	Macrophthalmidae
Genus:	Macrophthalmus
Subgenus:	Macrophthalmus
Species:	M. crassipes
Binomial name
Macrophthalmus crassipes (Milne Edwards, 1852)