Question

Describe the external characters of cockroach. What is the importance of exoskeleton of this insect?

Answer 1

Hint: Cockroaches are the insects that belong to the phylum arthropoda. There are about 4,600 species of cockroach out of which 30 species are associated with human habitat. They have a small head, flattened and broad body and are usually reddish brown to dark brown in colour.

Complete answer:
1.Cockroaches are the black or brown bodied insects with their size ranging from 0.6 - 7.6cm.
2.They have a broad body with relatively smaller head, flexible and long antenna, two ocelli and large compound eyes.
3.The mouth part consists of chewing mandibles, multiple touch and taste receptors and salivary glands that are located below the head.
4.They have a segmented body divided into three regions with three segments constituting thorax, ten segments constituting abdomen and head region.
5.The external surface of the body is covered by the chitinous exoskeleton. The exoskeleton in each segment consists of hardened plates called sclerites that are attached to each other by a flexible, thin articular membrane.
6.A pair of walking legs are present in each thoracic segment.
7.The first pair of wings are attached to mesothorax and the second pair of wings are attached to metathorax.

Importance of exoskeleton in cockroach:
The external surface of cockroach is covered by a tough exoskeleton that is made up of calcium carbonate. It provides attachment to the muscles and protects the internal organs. It is coated with wax inorder to prevent from getting wet and also aids in defence during the attack of predators.

Note: Sometimes allergic reactions are caused in humans by cockroaches. Tropomyosin is one of the proteins that is responsible for allergies and some of the allergens are also linked with asthma. Currently, Blattodea is considered as the group for cockroach species. Sometimes the group Blattopetra is also used to refer to the extinct cockroaches.