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Mollusc Classification


Class Monoplacophora

  • small class of deep-sea molluscs, capshapped shells and five or more pairs of gills

Class Aplacophora:

  • small, marine, wormlike, they have replaced the shell with tough spicules embedded in the mantle. Foot is sometimes small or absent


Class Polyplacophora:

  • flattened, marine, wormlike, with a shell divided into eight segments

Class Scaphopoda:

  • marine molluscs, surround themselves with a curved, tubular shell open at both ends

Class Gastropoda:

  • snails and slugs divided into three subclasses
  • Subclass Prosobranchia: fresh water, marine and land snails, sexes are separate, have small plat on the foot. Most marine snails are in this subclass
  • Subclass Opisthobranchia: sea slugs, butterflies and snails,most are marine, don not have a operculum and each organism has characteristics of both sexes. The shell may be internal, external or  absent
  • Subclass Pulmonata: land or freshwater airbreathing slugs and snails without and operculum

(shell family)

Class Bivalvia:

  • mollusks have two-part shells divided into five subclasses
  • Subclass Protobranchia: most primitive molluscs, which have unfolding gills used for respiration only
  • Subclass Taxodonta: marine animals, have both teeth and sockeing in each two shells. Their gills aare used for repiration and feeding
  • Subclass Anisomyria: mussles, oysters and scallops which live in salt and fresh water and contain bivalves
  • Subclass Eulamellibranchia: clams which live also have bivalves living in salt and fresh water. Their gills are used for feeding and repiration
  • Subclass Septibranchia: marine organisms without gills, which have developed a special muscle to pump water through the mantle cavity

Class Cephalopoda:

  • two subclass of these marine molluscs
  • Subclass Nautiloidea: called the nautilus, a primitive form of molluscs. They have a coiled external shell divided into compartments
  • Subclass Coleoidia: squid, octopuses, cuttle fish and argonauts, which all have a shell either interior or absent and a foot that has been modified into a number of tenticles





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