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Nerita polita Linnaeus, 1758 Description: Shell with spire depressed, width greater than height. Exterior glossy, usually smooth apart from fine axial growth lines, but occasionally with fine spiral ribbing. Columella deck smooth, columella straight, with 2-5 strong teeth at centre. Outer lip with about 20 weak denticles. Exterior colouration variable; marbled, streaked or banded with white, cream, grey or pink. Columella and inner band of outer lip usually deep orange or yellow, columellar deck white. Operculum calcareous, pink, grey or black, smooth and glossy with matt outer edge. Size: Up to 30 mm high, 39 mm wide. Distribution: Indo-West Pacific; in Australia, North West Cape, WA, around northern Australia to Sydney, NSW. Habitat: Feeds on microalgae on exposed rock surfaces around mid-tide level, but burrows a few centimetres into the sand when not feeding. (Morton and Burgin, 1986). Abundant in the tropics, uncommon in NSW. Remarks: The synonymy of this species is lengthy, with numerous forms having been described as species. A recent view of Krijnen (1999) is that the shell with orange aperture shown in Fig. 2 is Nerita antiquata Recluz, 1841, while the white aperture shell in Fig. 1 is the real Nerita polita Linnaeus, 1758. Fig. 1: Shark Island, Sydney Harbour (C.401783) Fig. 2: Moreton Bay, Queensland (C.011569) |
