The Purple Seastar has a patchy distribution. It ranges from Collaroy, New South Wales, south, including central Victoria, northern Tasmania, South Australia and southern Western Australia to Dongara. It is absent in southern Tasmania, a cold water area.
It may be common to abundant in some localities along southern shores and absent in others. CIOV states that no specimens have been found in the western region of Victoria, which is another cold-water area. Clark considers that it is characteristic of the south-western corner of Australia. (NSW, VIC, TAS, SA, WA)
Diameter 30-40 mm (70 mm).
The Purple Seastar has a thick domed body and is normally six-armed. It is similar in form to the Six-armed Seastar, P. gunnii, but is much larger being normally 60-80 mm across. It may grow to 140 mm across.
The arms of this species are more distinct than P. gunnii, but not as distinct as in the Common Eight-armed Seastar, Patiriella calcar. The furrow spines on the lower surface of the arms are usually in groupings of two, but may sometimes be groups of three in larger seastars, with one shorter than the other two.
The upper colour of the Purple Seastar is a uniform dark brownish crimson or purple, and below, the tube feet are coloured deep orange.
Ecology/Way of Life:
The Purple Seastar occurs under boulders and rocks and in pools at low tide levels and below, down to 15-20 metres. It prefers sheltered reef areas and seagrass beds. The Purple Seastar is an omnivorous feeder. It sits with its arms raised so that it may catch drifting animal and plant material drifting past. The Purple Seastar is more common than the Six-armed Seastar, Patiriella gunnii.
Interaction with Humans/Threats:
This seastar has a patchy distribution and is considered to be uncommon. Therefore any environmental disaster such as a large oil-spill will probably be devastating to local populations.
Bennett, I. (1987). W.J. Dakin's classic study: Australian Seashores. p. 346-7, Angus and Robertson.
Davey, K. (1998). A Photographic Guide to Seashore Life of Australia. p. 130, New Holland Press.
Clark, H.L. (1946). The Echinoderm Fauna of Australia: Its composition and origin. Carnegie Institution of Washington. Publication 566. pp. 567.
Edgar, G.J. (1997). Australian Marine Life: the plants and animals of temperate waters. p. 346, Reed.
Marine Research Group of Victoria. (1984). Coastal Invertebrates of Victoria: an atlas of selected species. p. 136, Museum of Victoria.
Shepherd, S.A. and Thomas, I.M. (1989). Marine Invertebrates of Southern Australia. pt. I. p. 412, South Aust. Govt. Press.
Text, map and photograph by Keith Davey.
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