A) Chiton
B) Nautilus
C) Dentalium
D) Pinctada
Correct Answer: A
Solution :
On the basis of body shape, symmetry and characteristic of foot, mantle, respiratory organs, nervous system etc molluscus are divided into 7 classes. The following animals belong to corresponding classes Chiton belongs to class-Amphineura or Polyplacophea. -Members of this class are mainly marine, body elliptical, dorsoventrally flattened. Head is not distinct, radula is present in buccal cavity. Nervous system non-ganglionates. It is also known as sea mouse or coat of mail shell. Nautilus belongs to class-Cephalopoda. It is a nocturnal and gregarious. They have large head with prominent eyes, radula, present well developed nervous system. They also possess sac in their mantle cavity, which releases dark colour ink, when animal is in danger. Dentalium belongs to class-Scaphopoda (skaphe = boat; podos = foot). The members of this class are mainly marine with elongated cylindricle and bilateraly symmetrical body. Distinct heart or eyes are absent. Nervous system with 4 pairs of main ganglia. Pinctada (pearl oysters) belongs to class-Pelecypoda or Bivalvia. Members are aquatic, mostly marine and some are freshwater forms. Body is soft and is protected by a bivalve shell. Eyes and radula absent.
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