Twisted Necklace Turban, Sydney or Heavy Turban Shell
The Twisted Necklace Turban has a temperate Australian distribution. It ranges from NSW, around southern shores, including SA to Geraldton, mid-coast WA. This species is rare or non-existent in Victoria and Tasmania, so there appears to be a disjunct distribution that may be caused by cold water currents off Vic and Tas. Macpherson and Gabriel discuss the finding of "fresh looking" fossils in Victorian waters, but not live ones, while the Marine Research Group of Victoria do not mention this species in their book "Coastal Invertebrates of Victoria" after intensive sampling and searching museum records. (NSW, VIC, TAS, SA, WA)
The Twisted Necklace Turban's shell is wide, large, solid and orb-shaped, being twice as wide as high. It grows to 95-110mm across the shell. It is a spiral, gastropod mollusc that is distinguished by its fine scaled, long striations, bold concentric ridges, and unusually sculptured operculum. Its sculpture consists of oblique, close, longitudinal, thin plate-like striations and bold, concentric, coarse ridges that appear like a twisted necklace. The early whorls are keeled. In western examples, the keel persists onto body are circular. The outer surface of the thick operculum is covered with fine prickles and raised spiral ridges that surround a central hollow. The exterior colour is usually greyish-green, but some are sand-coloured. Juveniles have an orange mottling. Inside the aperture and the columella are coloured white and are nacreous. The operculum is white outside and brown inside.
A heavily keeled, orange-coloured form exists in Western Australia called Whitley's Turban, Turbo torquata whitleyi. Intermediate forms occur along the southern shoreline, so although the western form is quite different to the eastern form in both shape and colour, it does not warrant full species recognition.
Ecology/Way of Life:
The Twisted Necklace Turban occurs at low tide levels and below to 20 metres. It is found in deep pools, or sheltered crevices, often browsing on algae. During the breeding season many may be found congregating in the region where the rock meets the sand.
Interaction with Humans/Threats:
This species appears to be common in NSW, SA and WA. However, because of its large size, it is under pressure from being taken by humans for food. Populations of this species need to be monitored so that they are not over-utilised.
The name Turbo is the Latin word for whirl or spinning top, while the name torquata comes from the Latin word torquere, meaning to twist and torques refers to a twisted necklace, while torquatus describes wearing a necklace.
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.277, Angus and Robertson. (as Turbo torquatus).
Davey, K. (1998) A Photographic Guide to Seashore Life of Australia. New Holland Press, p.92, Sydney. (as Turbo torquata).
Edgar, G.J. (1997). Australian Marine Life: the plants and animals of temperate waters. Reed. (as Turbo torquatus).
Jansen, P. (2000), Seashells of South-East Australia. p.16, Capricornia Publications. (as Ninella torquata).
Joll, L.M. (1980). Reproductive biology of two species of Turbinidae (Mollusca: Gastropoda). Aust. J. Mar. Freshwater. Res. v.31, 319-336.
Macpherson, J.H. and Gabriel, C.J. (1962). Marine Molluscs of Victoria. p.79, Melbourne University Press. (as Ninella torquata).
Shepherd, S.A. and Thomas, I.M. (1989). Marine Invertebrates of Southern Australia. Pt. II. p.561, South Australian Govt. Printing. (as Turbo (Ninella) torquatus).
Wells, F.E. and Bryce, C.W. (1988). Seashells of Western Australia. p.46, Western Australian Museum. (as Turbo torquatus).
Wilson, B.R. and Gillett, K. (1979). A Field Guide to Australian Shells: Prosobranch Gastropods. p.44, Reed. (as Ninella torquata).
Text, map and photograph by Keith Davey.
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