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Paragrapsus quadridentatus (Family Grapsidae)

Notched Shore Crab


This species is known only from western and central Victoria, and Tasmania. (TAS, VIC)


The flat carapace of the Notched Shore Crab is almost rectangular in shape, and slightly broader than long. These crabs reach a carapace width of 25-30 mm. The sides of the carapace are only slightly convex, and its surface is finely granular. In form, it is similar to the carapace of the Mud Shore Crab, Helograpsus haswellianus, but it has a distinctive projecting tooth on its edge where each side meets the rear surface. The males have large claws, similar in size. The carapace of the Notched Shore Crab is grey to pale brown, with a green sheen and dark red spots. The body and legs are light brown to cream in colour, and pale cream on the undersurface.

Ecology/Way of Life:

The Notched Shore Crab occurs at mid to low tide levels on medium to high-energy rocky shores and reefs down to 10 metres. Often it shelters under rocks on sand or shingle beaches, and is common on rocky coasts in its range. On rocky shores, the Notched Shore Crab, Paragrapsus quadridentatus lives lower on the shore than the Purple Shore Crab, Cyclograpsus granulosus, and on more muddy shores it is found with the Mottled Shore Crab, Paragrapsus gaimardi.

Interaction with Humans/Threats:

This species has a very restricted distribution on Tasmanian shores and the central and western areas of Victoria across Bass Strait. A large oil spill in this region could pose a moderate to major threat to this species.

Other Comments:

This species was described by Henri Milne-Edwards in 1837; Henri, professor of entomology at the Paris Museum, was the most important French contributor to the study of crustaceans in the 19th Century; the genus name he used comes from the Greek: para = near (in the sense of 'related to'), and grapsaios = crab; the species name is from the Latin: quadrus = square, referring to the shape of the carapace, and dentatus = toothed.

Further Reading:

Bennett, I. (1987). W.J. Dakin's classic study: Australian Seashores. p.224, Angus and Robertson.

Campbell, B.M. and Griffen, D.J.G. (1966). The Australian Sesarminae (Crustacea: Brachyura): Genera Helice, Helograpsus nov., Cyclograpsus and Paragrapsus. Memoirs of the Queensland Museum, 14(5), 127-176.

Davey, K. (1998). A Photographic Guide to Seashore Life of Australia. p.55, New Holland Press.

Edgar, G.J. (1997). Australian Marine Life: the plants and animals of temperate waters. p.214, Reed.

Marine Research Group of Victoria. (1984). Coastal Invertebrates of Victoria: an atlas of selected species. Museum of Victoria.


Text, map and photograph by Keith Davey.

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