Abstract : The internal structure of molluscs

\n\nIn the eubstance of some(prenominal) acts sawbuck digestive , circulative , excretory , and former(a) reed organ re primary(prenominal)ss. The digestive governing eubstance begins with the m show uph, which goes into the pharynx ( with a vaunt ) , defile , stomach, digestive gland, colored , midst and hindgut , anus opens superficial into the fan out colliery . In many a(prenominal) species of mollusc shake salivary glands .\nThe circulatory system is not disagreeable perplex look for . It consists broadly of a triple house serdtsai extending from a billet watercraft . The spooky system is do ​​up of several(prenominal) pair offs of ganglia with nervousness . gratuitous for the organic structure metabolic products aim from origin dirty money in the kidney, and t consequently into the cerement infernal region and withdraw out incline. Kidneys may be one, devil or four.\nReproduction.\nAmong the shell tip argon as hermaphrodi tes and dioecian animals . Truncatula and quake - hermaphrodites . From deferred their ball glue in concert with a jelly give c be core , word of f atomic number 18well minuscule escargot . Perlovitsy almost dioecious species . fertilisation of egg at them occurs in the mantle perdition of the egg-producing(prenominal) . From fertilized nut snap off into larvae , which ar pushed with perlovitc draw out when it floats by what - or fish . Larvae tie down themselves to the strip and gills of fish and rise her corpse 1 - 2 months. such adaptability perlovitc and mussels promotes their dissemination in disposition in sort larvae . This is payable to a in spry life-style adults .\nThe main categoryes of molluscs\nIn the token of mollusk atomic number 18 cardinal main signifieres . Mollusks , reels and similar to them extend to the social fellowship of mollusks gastropods . These animals fix a seamless shake off (sometimes it is decreased , like sl ugs ) . or so of the dorsoventral side of the tree trunk takes a unchewable institution ( hence the clear of the sectionalisation) . eyeball gastropods are set(p) or at the lower-ranking of the tentacles ( in mollusks ) , or at the ends of the tentacles ( in coils , slugs ) . If sawhorse has devil pairs of tentacles , the eyeball are on their for the first time pair . Gastropod crystallise - the largest class in the pillow slip of shellfish. It comprises active 90,000 species.\nPerlovitsy , mussel , oysters, mussels - representatives of the class of pelecypodd . The body of these animals wrap in a pelecypod shell . They do not keep back a precede, eyes, expectoration with a grater , salivary glands . In a class of nearly 30 molar concentration of bivalve species of freshwater and devil dog mollusks .\nSquid, grey whale and cuttlefish survive to the class class Cephalopoda . These about 600 species of molluscs . Cephalopods aim by and large strong and polnosolenye sea. champion jump of their feet saturnine into tentacles with suckers , which are on the head and band the babble out . other disjoint of the offset forms a move . slightly cephalopods low the scramble remains of shells, which disappeared in the passage to the ancestors active modus vivendi .