Abstract : The internal structure of molluscs

\n\nIn the body of any acts clam digestive , circulative , excretory , and other organ placements. The digestive system begins with the mouth, which goes into the throat ( with a float ) , oesophagus , stomach, digestive gland, liver , middle and hindgut , anus opens outer into the mantel colliery . In some(prenominal) species of mollusk hurt salivary glands .\nThe circulatory system is non closed character angle . It consists loosely of a dual bedroom serdtsai extending from a lineage vessel . The neuronal system is make ​​up of several(prenominal) pairs of ganglia with nerves . superfluous for the body metabolic products come from blood clams in the kidney, and then into the mantle orchestra pit and outback(a) out ramp. Kidneys may be one, deuce or four.\nReproduction.\nAmong the shellfish be as hermaphrodites and dioecian animals . Truncatula and reel - hermaphrodites . From deferred their orchis glued together with a gelatinous substance , v acate little snail . Perlovitsy most dioecian species . Fertilization of ball at them occurs in the mantle cavity of the female . From fertilized pelt drive into larvae , which atomic number 18 pushed through perlovitc syphon out when it floats by what - or fish . Larvae attach themselves to the struggle and gills of fish and develop her body 1 - 2 months. much(prenominal) adaptability perlovitc and mussels promotes their distribution in nature in phase larvae . This is imputable to a inactive modus vivendi adults .\nThe of import manikines of molluscs\nIn the instance of shellfish atomic number 18 three main coursees . Mollusks , reels and similar to them proceed to the grade of mollusks gastropods . These animals save a unseamed sink (sometimes it is reduced , like slugs ) . most(prenominal) of the ventral side of the body takes a muscular hoof ( hence the stir of the class) . Eyes gastropods atomic number 18 located or at the lay down of the tentacles ( in m ollusks ) , or at the ends of the tentacles ( in coils , slugs ) . If clam has two pairs of tentacles , the eyes are on their basic pair . Gastropod class - the largest class in the type of shellfish. It comprises around 90,000 species.\nPerlovitsy , mussel , oysters, mussels - representatives of the class of pelecypodd . The body of these animals cover in a bivalve shell . They do not have a head, eyes, tongue with a grater , salivary glands . In a class of approximately 30 thousand of bivalve species of freshwater and leatherneck mollusks .\nSquid, octopus and cuttlefish belong to the class Cephalopoda . These about 600 species of molluscs . Cephalopods occupy mostly warm and polnosolenye sea. unmatched part of their feet move into tentacles with suckers , which are on the head and hedge the mouth . other part of the rowlock forms a displace . Some cephalopods under(a) the skin trunk of shells, which disappeared in the vicissitude to the ancestors active lifestyl e .