Comparisons of radula types in Gastropods and Bivalve systems in the Phylum Mollusca.

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Comparisons of radula types in Gastropods and Bivalve systems in the Phylum Mollusca.

Introduction

Although not always apparent, within the Phylum Mollusca there is a uniform that is in the whole Phylum.  These are a muscular foot, visceral mass and mantle cavity.  Most within this phylum are soft bodied and as such require a shell for protection against predators.  The shell is formed by a fold of tissue that drapes over the visceral mass and secretes the shell, which is composed of Calcium carbonate.  The largest class with this phylum is the Gastropods.  These usually have conical, flattened or spiral shells which have been formed through torsion.  The class Bivalve are given their name because they have extensive mantle lobes which enable them to secrete a single shell composed to two valves by which the shell is hinged, which is the non calcified part.  The shell is closed by posterior and anterior muscles which draw the two halves tightly together.  Not only does the shell differ in these two classes but also their feeding apparatus and strategies.  Thus this investigation is to observe these differences and record them (Campbell and Reece 2002).

Aims:

To observe the morphological differences in Gastropods and Bivalves.

To observe and record the different types of radula found in Buccinium spp, Conus spp, Calliostoma spp, Patella spp and Littorinal.

To observe and record the different types of gills found in Cerastocterma edule (Cockle) Mytilus spp (Mussel), Pinna spp, and Katelysia spp.

Material and Methods.

A Patella (Limpet) was removed from the shell using a scalpel.  It was then placed under the dissection microscope and it was drawn dorsally to determine the structure and distinguish the various body parts.  This was then removed and with a sharp scalpel it was cut longitudally to determine in more detail the body conformation and identification of radula.

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Four slide specimens Buccinium spp (Whelk), Conus spp, Calliostoma spp(Subtidal snail), Patella spp (Limpet) and Littorina spp (Periwinkle), to determine under the light microscope at times ten magnification the differences in each radula.

A Mytilus edulis (Mussel) and Cerastoderma edula (Cockle) were both used as specimens for observation and recording of their various body parts.  Using a sharp scalpel the posterior adductor muscle was cut.  Pulling apart of the mantle lobe from the right valve, eventually the anterior adductor muscle could be cut exposing the soft body inside.  The retractor muscles were also cut and the soft body was removed from the ...

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