The Giant Limpet is restricted to south-western temperate shores. It ranges from Port Lincoln, South Australia to Shark Bay in central Western Australia. Some authors state it only ranges from King George Sound at Esperance to Shark Bay in Western Australia.(SA, WA)
The Giant Limpet is the largest Australian limpet. It grows to a length of 110 mm in length, 82 mm in width and 47 mm in height. The shell is solid, oval-shaped, conical, and often quite tall. The shell apex is one third of the way from the rear.
The shell surface is sculptured with numerous irregular, uneven, radiating ribs and riblets of varying size and widths. There are about 22 coarse primary ribs, with many smaller ones up to about 50 in number. The shell margin is finely crenulated, with groups of 2 to 4 longer teeth-like denticles around its inner surface.
The Giant Limpet's shell is coloured greenish grey with cream to white ribs and brownish interspaces. Inside the shell is brown or fawn with a porcelain-like sheen. The muscle scar is dark brown. The edge of the shell is conspicuously marked with dark blotches, often in pairs. Large limpet shells may be heavily eroded to a greenish-grey, and the ribs are only discernible around the margin of the shell.
Its full name is Patella (Scutellastra) laticostata. The sub-genus Scutellastra H. and A. Adams, are all large, solid shells with a porcelainous interior. They differ from other members of the Patella group by small differences in their radula (tongues).
Ecology/Way of Life:
The Giant Limpet is commonly found at all tidal levels on rocky ocean shores of south-western Australia. Almost every individual appears to have one or more commensal Patelloida nigrosulcata, a small limpet attached to its shell. An excellent photo in Wells in Plate 5 shows how the smaller limpet, Patelloida nigrosulcata, has left a deep scar in the shell of the larger Giant Limpet. The word "commensal" means eating at the same table.
Interaction with Humans/Threats:
Edgar states that the population numbers of the Giant Limpet may be declining due to excessive "fishing pressure". Edgar does not state whether Giant Limpets are being used for fish bait, or are being eaten by humans. A number of them would certainly be a large enough volume to make it worthwhile for them to be collected as food.
Davey, K. (1998). A Photographic Guide to Seashore Life of Australia. p. 78, New Holland Press.
Edgar, G.J. (1997). Australian Marine Life: the plants and animals of temperate waters. p. 233, Reed.
Shepherd, S.A. and Thomas, I.M. (1989). Marine Invertebrates of Southern Australia. pt. II. p. 548, South Aust. Govt. Press.
Wells, F.E., and Bryce, C.W. (1988), Seashells of Western Australia. p. 38-9, Western Australian Museum.
Wilson, B.R. and Gillett, K. (1971). A Field Guide to Australian Shells: Prosobranch Gastropods. p. 34, A.H. and A.W. Reed.
Text, map and photograph by Keith Davey.
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