The Five Main Classes of Shell

Image of Gastropods Image of Bivalves Image of Chitons Image of Tusk Shells Image of Cephalopods
Gastropoda Bivalvia Polyplacophora Scaphopoda Cephalopoda
(Gastropods) (Bivalves) (Chitons) (Tusk Shells) (Cephalopods)

PHYLUM: MOLLUSCA

Description
Molluscs are invertebrate animals with an unsegmented, basically bilaterally symmetrical body, generally consisting of head, foot, visceral mass and mantle. The majority of molluscs live in the sea or in fresh water and use gills for respiration. Certain terrestrial gastropods breathe by lungs.
It is the characteristic of the molluscs that they have no internal supporting skeleton. The shell serves to protect the body against the outside world, but it does not provide support or rigidity. The shell is a product of secretion which by deposition of material can be thickened, enlarged and if necessary repaired, but it plays no part in the metabolism of the animal.
Classification:

Natural History Museum > Archerd Shell Collection > Shell Classes