Question

explain the characteristics of mollusca​

Answer 1

Explanation:

• The organisms belonging to phylum Mollusca exhibit the following characteristics:

• They are mostly found in marine and freshwater. Very few are terrestrial and found in moist soil.

• They exhibit organ system level of organization.

• Their body has a cavity.

• The body is divided into head, visceral mass, muscular foot and mantle.

• The head comprises of tentacles and compound eyes.

• The body is covered by a calcareous shell.

• The muscular foot helps in locomotion.

• They have a well-developed digestive system, the radula is the rasping organ for feeding.

• They respire through the general body surface, gills or pulmonary sac.

• The blood circulates through the open circulatory system.

• They have a pair of metanephridia that helps in excretion.

• The nervous system consists of number of paired ganglia and nerves.

• The tentacles, eyes, osphradium, and statocysts act as the sensory organs.

• The sexes are separate in most of the molluscs but some species are hermaphrodites. Fertilization may be external or internal.

• They are generally oviparous with indirect development.

Answer 2

Molluscs (also know as mollusks) are soft-bodied, bilaterally symmetrical, segmented, coelomate animals; usually shelled having a mantle, ventral foot, anterior head, and a dorsal visceral mass.

Characteristic Features of Phylum Mollusca

• They are bilaterally symmetrical.
• They are triploblastic, which three layers.
• They show organ system grade of organisation.
• The body is soft and unsegmented.
• Body is divisible into three regions – head, a visceral mass, and ventral foot.
• Body is covered by a mantle and shell.

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