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Ischnochiton australis (Family Ischnochitonidae)

Australian Chiton

Distribution

Distribution:

The Australian Chiton ranges from southern Qld, around south-east Australian shores including NSW, Vic and Tas to the Great Australian Bight, SA. (QLD, NSW, VIC, TAS, SA)

Features:

The Australian Chiton is a large, flat, oval shaped chiton, with a medium-width girdle. The girdle is sculptured with large, thick, keeled, pebble-like scales. It is the largest species of the Ischnochiton genus that occur on southern Australian shores. It grows to a length of 70-90 mm and a width of 40 mm.

The chitons end valves have strong, irregular shaped, radiating ribs. Its lateral (side) areas have diagonal ribs. The central valves are longitudinally ribbed. The pleural area (side slope region of a valve) has fine longitudinal ridges. The sculpture is often obliterated by erosion.

The valves and girdle are mostly dark green to greenish-brown, rarely blue. The lateral areas are brown in colour, while the medial and pleural areas are green with brown flecks.

Ecology/Way of Life:

The Australian Chiton is commonly found under rocks on reefs and on rocky shores on high-energy coasts at low tide level and below to 8 metres. If the boulder on which it is located is lifted from the water, the Australian Chiton will curl up and drop back into the water. According to Shepherd & Thomas (1989) no other chiton exhibits this escape response.

A western form Ischnochiton evanida (Sowerby 1840) which has a smooth shell in the central areas, was considered by Macpherson & Gabriel (1962) to be insufficiently different to warrant being considered to be a different species. According to Iredale and Hull, this form occurs in Tasmania, Victoria and South Australia (Macpherson & Gabriel, 1962).

Preferred Image

Interaction with Humans/Threats:

This chiton is very common across its fairly extensive range so is probably not under threat from human activities.

Other Comments:

Ischnochiton comes from the Latinised form ischium of the Greek word ischion, meaning the hip joint, while chiton is the Greek word for tunic, which was pleated. Australis or Auster is the Latin word for the south wind.

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.263, Angus & Robertson.

Cotton, B. C. (1964) South Australian Mollusca: Chitons. p. 52. Govt. Printer S. A. (as Ischnoradsia australis).

Davey, K. (1998) A Photographic Guide to Seashore Life of Australia. p.69, New Holland Press, Sydney.

Edgar, G.J. (1997). Australian Marine Life: the plants and animals of temperate waters. p.220, Reed.

Iredale, T. & Hull, A. F. B. (1927). A monograph of the Australian Loricates. Royal Zoological Society of New South Wales.

Macpherson, J. H. & Gabriel, C. J. (1962). Marine Molluscs of Victoria. p.19, Melbourne University Press. (as Ischnoradsia australis)

Marine Research Group of Victoria (1984). Coastal Invertebrates of Victoria: An atlas of selected species.p.16, Museum of Victoria.

Shepherd, S. A. & Thomas, I. M. (1989). Marine Invertebrates of Southern Australia. Pt. II. p.513, South Australian Govt. Printing.

Acknowledgments:

Text, map & photograph by Keith Davey.

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Images and Multi-media:  
Attached Image  
image/jpeg 22022 bytes Australian Chiton
Distribution Map  
image/gif 997 bytes Distribution of Australian Chiton

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