Zoology-Mollusca Info Essay

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Zoology Lab Report Mollusca Kingdom- Animalia Phylum-Mollusca Class-Bivalvia Genus-Corbicula Habitat- * Most are marine, but many live in brackish water and in streams, ponds and lakes. Feeding- * Most are suspension feeders. Their respiratory currents bring both oxygen and organic materials to their gills, where cilia tracts direct them to the tiny gill pores. Reproduction- * They are diecious. Fertilization is usually external. Marine embryos go through three free-swimming larval stages-trochophore, veliger larva and young spat- before reaching adulthood. * In fresh water clams, fertilization is internal and some gill tubs become temporary brood chambers. Locomotion- They move by extending their muscular foot between the valves. They pump blood into the foot, causing it to swell and to act as an anchor in mud or sand. Then, longitudinal muscles contract to shorten the foot and pull the animal forward. Osmoregulation: They are isosmotic. This means that they have the same level of osmotic pressure diffusing and the solvent flows through a semi porous membrane from a region of low solute concentration to a region of high solute concentration. Therefore, they can inhabit, adjust and sustain stability in their new environment when migrating. Circulation: They have an open circulatory system, meaning the blood does not circulate entirely within vessels but is collected from the gills, pumped through the heart, and released directly into spaces in the tissues from which it returns to the gills and then to the heart. Such a blood-filled space is known as a hemocoel ("blood cavity"). The hemocoel has largely replaced the coelom, which is reduced to a small area around the heart and to the cavities of the organs of reproduction and excretion. Biological importance: Certain species are of direct or indirect commercial and even medical

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