Question

Larva of Bombyx mori is
(a) Caterpillar
(b) Trochophore
(c) Nymph
(d) Cocoon

Answer 1

Hint Arthropods are a triploblastic animal with the externally segmented body. Sexes are separate and development of animals involves metamorphosis. Bombyx mori shows complete metamorphosis by egg, larva, pupa and imago.

Complete Answer:
Bombyx mori is also known as silk moth belonging to the phylum Arthropoda. It shows complete metamorphosis with indirect development of larva. The larva is also known as caterpillar or silkworm.
Silkmoth is used for the production of silk, it was first discovered by China and then introduced throughout the world. The adult female is larger than male and both the adults have an externally segmented body with thick bristle on the body surface. Female secrete pheromone bombykol to attract male. Females may lay about 300-400 eggs in roughly 8-16 days. Newly hatched larvae mainly feed on mulberry leaves and lettuce. After 45 days pupa occurs inside a cocoon which is continuous white and the yellow strand of silk. Silk obtained by killing pupa inside hot water. About 1000 metres silk thread obtained from a single cacoon.

Additional information:
Insects with gradual metamorphosis include egg, nymph and imago. Nymph resembles the adult in the mode of life but it does not consist of wings. This type of metamorphosis is shown by cockroaches, grasshoppers, locusts, termites, bed bugs and lice.
Trochophore larva is the indirect development of sexual reproduction by marine animals like Nereis and some molluscs. It is free-swimming larva with anterior end broader than the posterior end girdled by the ring of cilia. It may be spherical or appear in shape. It is then transformed into a veliger form with a well-developed body structure which settles down at the bottom of the water and then transforms into an adult.

So, the correct answer is the caterpillar.

Note: In the case of a silk moth males die soon after copulation and females die soon after laying eggs. The adult can live for 2-3 days only without feeding because their mouthpart is reduced or absent.