New Zealand Siphon Shell
The New Zealand Siphon Shell is restricted to temperate Australia and New Zealand. Its range includes Southern Queensland, New South Wales, Victoria, South Australia and south-western Western Australia, excluding Tasmania. It also occurs on the warmer shores of New Zealand. (QLD, NSW, VIC, SA, WA)
This siphon shell is quite depressed (flattened) and thin with a thickened margin. Its shell height is less than one-third of the shell height. The shell's length 15-25mm, width to 19mm, and height 6-8mm. The shell apex is offset to the left and occurs slightly towards the rear from the centre (posterior).
Its shell sculpture is made up of about 17-18 broad main radial ribs that are widely spaced, with 2-3 riblets between. The outer margin of the shell is irregular, sometimes broken, with the primary ribs extending beyond the outer lip. Underneath the shell, the conspicuous siphonal groove extends from the apex to the shell margin. The shell may be quite eroded or overgrown with marine growths such as lithothamnion and micro-algae.
The outside of the shell is greenish-cream, with white rib peaks, and brownish flecks in the shallow spaces. The animal's visceral mass and foot are pale-green-grey in colour.
Inside the shell is glossy cream-white, tinged with tan to yellow. There is a brown to orange-coloured muscle scar, which is called the spatula because it is shaped like a spoon. The thickened shell lip is white mottled with irregular brown rays aligned under the outside rib spaces.
Ecology/Way of Life:
The New Zealand Siphon Shell occurs in groups at middle to high-tide levels on rock platforms, on medium to high-energy shores. It is usually found at a lower level on the shore than Siphonaria diemenensis. This species has a flatter shell than S. diemenensis and the grooves between the ribs are lighter in colour. The egg mass is quite similar to S. diemenensis, but has a flatter girdle and is much lighter in colour at all stages of development.
Interaction with Humans/Threats:
It is unknown if there are any threats to this species. It appears to be common to abundant on the shores within its range.
It is also known as Bacon's Siphon Shell, Siphonaria baconi, in Western Australia.
Davey, K. (1998). A Photographic Guide to Seashore Life of Australia. p. 117, New Holland Press.
Edgar, G.J. (1997). Australian Marine Life: the plants and animals of temperate waters. p. 267, Reed.
Jenkins, B.W. Redescriptions and relationship of Siphonaria zelandica to S. australis with a description of S. propria sp. nov. (Mollusca: Pulmonata: Siphonariidae) J. Malac. Soc. Aust. 6(1-2), 1-35.
Macpherson, J.H. and Gabriel, C.J. (1962). Marine Molluscs of Victoria. p.264, Melbourne Univ. Press. (as S. baconi)
Marine Research Group of Victoria. (1984). Coastal Invertebrates of Victoria: an atlas of selected species. p. 78, Museum of Victoria.
Shepherd, S.A. and Thomas, I.M. (1989). Marine Invertebrates of Southern Australia. pt. II. p. 612, 877, South Aust. Govt. Press.
Short, J.W. and Potter, D.G. (1987). Shells of Queensland and the Great Barrier Reef. P. 122, Golden Press.
Text, map and photograph by Keith Davey.
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