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Molluscs |
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Molluscs
include all the shelled creatures of the seashore, with the exception of
the barnacles. Molluscs are abundant in the region between high and low
tide and are a major feature of all rocky ocean shores. Molluscs form one
of the largest groups in the animal kingdom, with more than 80,000 known
species. Molluscs form a very well defined group and although their outside
features may vary greatly in form and colour, their internal structure is
constant.
It is believed that modern molluscs evolved from a creature similar to the one above. It had its gills, reproductive organs and excretory organs within its mantle cavity at the rear of the animal. Although there are numerous limpet-like fossils which are of this structure, only one species has been brought up from 5,000 metres near the coast of Mexico in the pacific Ocean. It was first captured in 1957. During development, a ll modern molluscs undergo torsion, where the mollusc body twists so that the mantle cavity, and the organs it holds, come to rest over the head, facing the incoming current. Some Molluscs groups which are featured in this intertidal web site are:
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Chitons
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Life
on Australian Seashores Scientific Consultant: Phil
Colman
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