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Ischnochiton elongatus (Family Ischnochitonidae)

Elongated Chiton


The Elongated Chiton ranges from New South Wales around southern Australian shores to Shark Bay, Western Australia, including Tasmania. It is found in abundance east of Spencers Gulf (Cotton, 37). (NSW, VIC, TAS, SA, WA)


The Elongate Chiton is a medium sized chiton, with a very long oval shape. It is 25-35 mm long and 12 mm wide. The front valve and side areas have fine, often weak, radiating, noduled ribs. Fine, irregular, radiating rows of fine bumps border the front edge. These rows of bumps overlie a finer sculpture. The pleural area has very fine striations. The moderately wide girdle has scales that appear snake-like. The medium-sized, uniform, round to oval-shaped, girdle scales are striated with deep grooves, six to a scale. The sculpture is weak in juveniles but is strongly expressed in adults.

The colour and colour patterns of the Elongated Chiton are extremely variable. The most common form has a black background with a pale white stripe along the centre. Other colours may include olive green, grey, brown, black, blue, purple, red, or cream, with various coloured dots, stripes or wavy lines. There is so much variation in this chiton's colouration that there is no use describing the range which occurs.

Ecology/Way of Life:

The Elongate Chiton occurs at the lowest tide levels and below to 10 metres, or in rockpools, on sheltered to moderately exposed shores, usually under boulders or stones embedded in sand. It is a common algivore.

This is an abundant chiton found under rocks on Victorian and Tasmanian shores. It resembles the Lined Ischnochiton, Ischnochiton lineolatus, but lacks the fine, dark streaking, and is shorter. The Elongate Chiton, Ischnochiton elongatus grows to 25 mm while the larger Variegated Ischnochiton, Ischnochiton versicolor, grows to 60 mm. The Variegated Chiton, Ichnochiton elongatus, has smaller girdle scales and finer ridges in the pleural region.

Interaction with Humans/Threats:

This is a very common species along Victorian shores and does not appear to be under threat.

Further Reading:

Bennett, I. (1987). W.J. Dakin's classic study: Australian Seashores. p. 174-5, Angus & Robertson.

Cotton, B.C. (1964) South Australian Mollusca: Chitons. P.36, Govt. Printer, South Australia.

Davey, K. (1988). A Photographic Guide to Seashore Life of Australia. p. 69, New Holland Press.

Edgar, G.J. (1997). Australian Marine Life: the plants and animals of temperate waters. p. 221, Reed.

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

Marine Research Group of Victoria. (1984). Coastal Invertebrates of Victoria: an atlas of selected species. p. 14, Museum of Victoria.

Shepherd, S.A. & Thomas, I.M. (1989). Marine Invertebrates of Southern Australia. pt. II. p. 510, South Aust. Govt. Press.


Text, map & photograph by Keith Davey.

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