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Parasesarma erythodactyla (Family Grapsidae)

Red-fingered Marsh Crab


The Red-fingered Marsh Crab ranges from central Queensland to Eden in southern New South Wales. There are isolated populations in central Victoria at Westernport, Anderson's Inlet and Corner Inlet; elsewhere this species is widespread in the Indo-west Pacific Ocean. (NSW, QLD, VIC, SA)


Sesarmid crabs have a square shaped carapace (the shell). They also have equal-sized chelae (claws), those of the males being much larger and more colourful than those of females. Adults reach 20-30mm across the carapace. In mature males, the carapace is emerald green and the chelae are orange and white with bright red-tipped fingers; in females and immature crabs, the carapace is greenish-black to nearly black; the chelae are much smaller than in males, and are tipped with red.

Ecology/Way of Life:

Red-fingered Marsh Crabs are widely found in mangrove swamps, in salt marshes of estuaries, and in river or tidal-creek banks and may be quite common in some localities. Occasionally they occur on protected mud shores near the sea. They are herbivorous. This species is often associated with the Semaphore Crab, Heloecius cordiformis, the Spotted Smooth Shore Crab, Paragrapsus laevis, and the Orange-clawed Uca, Uca vomeris, and has its burrows in the same areas, such as mangroves. When disturbed, it is swift moving and rapidly runs to and enters any nearby burrow it can fit into. These crabs can tolerate low salinities and may occur far up rivers away from the sea. In some areas it may be the most abundant crab.

Interaction with Humans/Threats:

This common, wide-ranging species appears able to withstand habitats that can be quite polluted by floating stormwater rubbish.

Other Comments:

This species was described by Wilhelm Hess in 1865, based on a specimen collected at Sydney, and placed in the genus Sesarma. The origin of this genus name is uncertain; the species name is from the Greek: erythros = red and dactylos = finger, referring to the bright red fingers on the claws in this species.

Further Reading:

Bennett, I. (1987) W.J. Dakin's classic study: Australian Seashores. p.230. Angus and Robertson.

Davey, K. (1998) A Photographic Guide to Seashore Life of Australia. p.59. New Holland Press.

Edgar, G.J. (1997) Australian Marine Life: the plants and animals of temperate waters. P.216. Reed.

Jones, D. and Morgan, G. (1994) A Field Guide to Crustaceans of Australian Waters. p.187. Reed.

Marine Research Group of Victoria. 1984. Coastal Invertebrates of Victoria: an atlas of selected species. p.116. Museum of Victoria.


Text, map and photograph by Keith Davey.

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