A cluster of blue periwinkles, Nodilittorina unifasciata, on the surface of calcareous sandstone, Blairgowrie, Victoria Australia. Periwinkles are cha

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A cluster of blue periwinkles, Nodilittorina unifasciata, on the surface of calcareous sandstone, Blairgowrie, Victoria Australia. Periwinkles are characteristic creatures of rocky shores. N. unifasciata is found in crevices and depressions in the rock ( as here ), high up in the intertidal zone, where it may be exposed to the air for several hours at each tide. It feeds by grazing on alga and have a coiled snail-like shell that is closed by a horny lid, the operculum. The animal attaches itself initially to its substrate by means of its foot. In response to drying, (here, as the tide falls) the foot produces a mucus material which covers the mouth of the shell and hardens, providing a firm but temporary attachment, and allowing the operculum to be completely closed.

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Size: 3413px × 5120px
Photo credit: © DR JEREMY BURGESS/SCIENCE PHOTO LIBRARY / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: australia, biological, biology, blairgowrie, blue, calcareous, intertidal, nodilittorina, operculum, periwinkle, rocky, sandstone, shore, unifasciata, zone, zoological, zoology