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Austrocochlea porcata (Family Trochidae)

Zebra Top Shell


The Zebra Top Shell ranges from Townsville, central eastern Qld, around southern shores, including NSW, Vic, Tas and SA to Geraldton, WA (NSW, VIC, TAS, SA, WA).


The Zebra Top Shell is the common zebra-striped ribbed top shell. Its shell is conical and globe-shaped, with a sharp apex. It grows to a length of 25-30mm. It is similar in shape to Ribbed Top Shell, A. contricta, and the two have been considered the one species until recently. This species is distinguished by its less tall, broken spiral ridges, and the oblique black and white banded pattern overlying the light grey to white coloured shell. This shell is taller than other Austrocochlea species.

Ecology/Way of Life:

The Zebra Top Shell occurs in large numbers at mid-tide level and below on rocky ocean shores, especially in moist areas and rockpools, as well as in estuaries. It is very common in south-eastern Australia. The bands are created when the animal eats a particular kind of algae and secretes one of the by-products of digestion into its shell as it grows. The algae has a seasonal occurrence, so the growing shell becomes banded.

Interaction with Humans/Threats:

Is this form really a separate species, A. porcata, or a variant of A. constricta? Only further research on the Austrocochlea genus will tell. Both these forms are extremely abundant across their range and are not under threat from human activities.

Other Comments:

Austrocochlea porcata, Adams, 1853. Austrocochlea is made up of two parts. Austro comes from the Latin word australis or auster, meaning the southern wind and cochlea from the Latin word coc(h)lea , meaning a shell or a screw. The Greek word kochlias means a snail. Porcata may come from the Latin porcus, meaning a swine or pig.

Further Reading:

Bennett, I. (1987). W. J. Dakin's classic study: Australian Seashores: a guide to the temperate shores for the beach-lover, the naturalist, the shore-fisherman and the student. p.391-2, Angus & Robertson.

Davey, K. (1998) A Photographic Guide to Seashore Life of Australia. p.88, New Holland Press, Sydney.

Edgar, G.J. (1997). Australian Marine Life: the plants and animals of temperate waters. p.240, Reed.

Jansen, P. (2000), Seashells of South-East Australia. p.20, Capricornia Publications.

Jones, D. & Morgan, G. (1994). A Field Guide to Crustaceans of Australian waters. Reed.

Macpherson, J. H. & Gabriel, C. J. (1962). Marine Molluscs of Victoria. p.69, Melbourne University Press.

Marine Research Group of Victoria (1984). Coastal Invertebrates of Victoria: An atlas of selected species. p.38, Museum of Victoria. (Grouped in with A. constricta; see diagram).

Wells, F. E. & Bryce, C. W. (1988). Seashells of Western Australia. Western Australian Museum.

Wilson, B. (1993) Australian Marine Shells. Prosobranch gastropods. Odyssey Publishing.

Wilson, B. R. & Gillett, K. (1979). A Field Guide to Australian Shells: Prosobranch Gastropods. Reed.


Text, map & photograph by Keith Davey.

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