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 lichens.Periwinkles 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 | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / Burgess, Dr. Jeremy |
Taille de l’image : | 3413 px × 5120 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |