Invertebrate Zoology

Metamorphosis is the process of transformation from an immature form to an adult form in two or more distinct stages. metamorphosis generally takes place in insects or amphibians and some molluscs, crustaceans, cnidarians, echinoderms and tunicates.
Metamorphosis is seen in frogs which are developed form of the larval stage called the tadpoles. Also, metamorphosis is seen in insects where the adult forms develop from the larva and which also includes the pupal or resting stages as in silkworms.
So, the correct answer is option D.

Incomplete metamorphosis involves three stages: egg, nymph, and adult. The nymph resembles a small adult and undergoes gradual development through molts. Complete metamorphosis has four stages: egg, larva, pupa, and adult. Three-stage development is characteristic of insects like grasshoppers and true bugs.

Insects shed their exoskeleton in order to grow which is known as moulting. Moulting allows the body of insects to expand under protected conditions. An instar is a developmental stage of insects, between each moult until sexual maturity is reached.

Grasshoppers, cockroaches, and lice undergo incomplete metamorphosis (nymph stage), whereas mosquitoes undergo complete metamorphosis (egg, larva, pupa, adult).

Winged adults lay eggs on the food plant on which their larvae, known as caterpillars, will feed. The caterpillars grow, sometimes very rapidly, and when fully developed pupate in a chrysalis. When metamorphosis is complete, the pupal skin splits, the adult insect climbs out and, after its wings have expanded and dried, it flies off. Some butterflies, especially in the tropics, have several generations in a year, while others have a single generation, and a few in cold locations may take several years to pass through their whole life cycle.

In complete metamorphosis, organism passes through four distinct stages in their life cycle. Moths pass through caterpillar and pupa stage while reaching from egg to adult stage, hence they undergo complete metamorphosis.

Complete metamorphosis consists of four distinct stages: egg, larva, pupa, and adult.

From 27th segment upt 23-25 segments in front of the anus in intestine of earthworm, lies a highly glandular and vascular part called typhosole. It greatly increases the effective absorption area for digested food in the intestine.

Houseflies feed on liquid or liquefied food by secreting saliva onto solid food and then sucking it up. This is a form of saprozoic or saprophytic-like feeding behavior.

Each segment in the strobila of tapeworm, containing a complete sexually mature reproductive system is proglottid.

Respiration takes place through the moist surface of the body of an earthworm. Moist surface aids in easy diffusion of gases. Haemoglobin is the respiratory pigment that helps in transportation of oxygen to different parts of the body. 

Earthworm is able to move with the help of combined efforts of muscles and setae. Both of them help in longitudinal and circular movement of the muscles. The coelomic fluid acts as a hydraulic skeleton in the body of an earthworm. It helps to provide stiffness to the body and relaxation of the muscles. Thus option D is correct. 

Earthworm is a reddish brown terrestrial invertebrate that inhabits the upper layers of the moist soil rich in decaying matter. It is nocturnal and during the daytime, it lives in burrows made by boring and swallowing the soil.