Austrolittorina unifasciata (Gray, 1826)
Abundant on hard surfaces of intertidal and littoral areas on rocky headlands in the Solitary Islands Marine Park. Endemic to Australia, distributed from Yeppoon in central Queensland south to Victoria and Tasmania and around to North West Cape in Western Australia. Also common at Lord Howe Island.
Found from as much as 10 m above the high tide level to the low tide level, in cracks and crevices on exposed coasts, more open areas on sheltered coasts.
Colour blue-grey, lighter on upper half of whorls and base, apex brown. Columella brown, aperture brown with white band internally. This abundant species may be found in densities approaching 1000 animals per square metre in favourable locations. Able to tolerate harsh summer sun of Queensland and the cold of southern Tasmania, there are separate sexes and the eggs are fertilised internally. The female releases the egg capsules, each containing a single fertilised egg into the sea where veliger larvae hatch out, eventually settling on the shore where they feed on microalgae and lichens. Large concentrations of settling young increases competition for food and with growth, animals move upshore to the limit of their physiological tolerance to take advantage of the reduced competition. Larger animals are more tolerant to high temperatures and lower humidity. Grows to 25 mm but usually smaller than 15 mm. Commonly 15 mm or larger at Lord Howe Island.
Graham J. Edgar. Australian Marine Life, 2nd Edition, 2008. Reed New Holland Publishers. pp.286-7.
The Seashells of New South Wales, Des Beechey, Senior Fellow, Australian Museum, Release 25. Website at https://seashellsofnsw.org.au/Littorinidae/Pages/Austrolittorina_unifasc.... Accessed 16/10/2018.