Invertebrate Zoology

Whether an animal undergoes complete or incomplete metamorphosis, the life cycle always begins with an egg. The larva and pupa are subsequent developmental stages that occur after hatching.

In the life cycle of a butterfly or moth, the larval stage is commonly referred to as a caterpillar. The pupa is the next stage (often inside a cocoon or chrysalis), and the butterfly is the final adult stage.

The egg apparatus is composed of one egg cell and two synergids, and the synergids possess the filiform apparatus.

Metamorphosis is the process of transformation from an immature form to an adult form in two or more distinct stages, common in insects like butterflies.

An exoskeleton is a hard external covering that provides support and protection for the bodies of many insects and other arthropods.

The life cycle of a butterfly begins with the egg stage, which is laid by the adult butterfly on a host plant.

The larva stage is an early, active, and often worm-like phase in the life cycle of many insects. It occurs after the egg hatches and before the insect enters the pupa stage.

Termites rely on symbiotic flagellates in their gut to break down the cellulose found in wood. Without these microorganisms, termites would be unable to digest their primary food source.

The silk worm spins a cocoon around itself during the pupa stage of its life cycle. This is the stage where the silk is harvested.

The silk fiber is produced by the silk worm as a liquid secretion from its glands, which hardens into a cocoon. The silk is harvested from this cocoon.

The second type of water-current system found also in calcareous sponges, is at first characterized by choanocytes that surround fingerlike projections of the sponge wall. So the correct option is ' sycon'.

A) The heart is not membranous.

Earthworms belong to the phylum Annelida. Their primary excretory organs are segmentally arranged tubes called nephridia.

Soil bacterium Bacillus thruingiensis (Bt) produces proteins that kill certain insects like lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes).Bacillus thuringinesis forms some intracellular protein crystals. These crystals contain a toxic insecticidal protein. The Bt toxin protein exists as an inactive toxin and is coverted into an active form due to the alkaline pH of the alimentary canal that solubilities the crystals. The activated toxin binds to the surface of midgut epithelial cells and creates pores which cause cell swelling and lysis and finally cause death of the insect.

Erythrocruorin is a respiratory pigment found in some annelids and arthropods. In the genus Limulus (horseshoe crab), it is dissolved directly in the blood plasma.