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A diagram showing the basic anatomy and arrangement of internal organs of the saltwater limpet Patella vulgata. Limpets are aquatic snails with shells that are broadly conical in shape, although the term also refers informally to all gastropods whose shells have no obvious coiling. Members of the family Patellidae, which includes the species shown, are often called the "true limpets". These are capable of mobility, but also use their muscular foot and mucus to apply suction and resist wave movement and predation. This image allows the viewer to see the neural torsion common to most snails, wherein the visceral nerves are "twisted" causing the rectum and kidneys to open near the animal's head. This was the result of once having had an ancestor with a coiled shell— the coiled shell is now gone, but the torsion (in the Patellidae) remains (while some other gastropods have subsequently "detorted"). Direction of blood flow is indicated by small arrows around the circumpallial vein and then into and out of the heart. Not shown are the hundreds of tiny pallial gills which form a ring over this vein and help reoxygenate the animal's blood. Diagram: K.D. Schroeder Recently featured:
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from Wikipedia picture of the day feed http://ift.tt/2heNvT3
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