Phylum Mollusca ("Soft of Body")
Description
Phylum Mollusca Is home to 110,000 different species. They are mostly marine, but their habitat varies widely from marine to aquatic to terrestrial. Their body's have a digestive tract with two openings. they are coelomates, have a circulatory system and a very complex nervous system. They also possess bilateral symmetry. Their body plan includes three main body areas; a single muscular foot, which is very strong and can move very efficiently. Next is the visceral mass, which is where the internal organs of the mollusc are located. The last of the three is the mantle, which is attached to the dorsal surface of the visceral mass and hangs down the sides of it. There is a number of adaptations that Molluscs possess. The Radula, which is unique to only the phylum Mollusca, is a tooth covered "tongue" that has the ability to snatch things up into the mouth of the organism. Molluscs also have gills, and an open circulatory system. They have a nephridia for excretion, which functions similar to a kidney. They have a siphon that can be used for movement, taking in water and pumping it out to propel them self forward. Molluscs reproduce sexually, chiefly with external fertilization, although land snails are hermaphroditic.