a note on exoskeleton of cockroach
Answers
Answer:A cockroach is similar to other insects in the way its body is constructed. The body is divided into three parts—head, thorax, and abdomen. Three pairs of legs are attached to the thorax. Most cockroaches have three joints on each leg, which means they have 18 knees!
The skeleton is made of a hard substance called chitin. When a skeleton is on the outside, it is called an exoskeleton. The exoskeleton supports and protects the roach’s insides. Because it is hard, the exoskeleton cannot grow. To get around this problem, a cockroach sheds its exoskeleton several times per year. Then its body grows quickly before the new exoskeleton forms. When the exoskeleton has just been shed, the cockroach’s skin appears very light. Then, after about eight hours, the skin becomes dark again.
Wings, when present, overlap one another and lay flat over the back, but the tips of the hind pair do not fold. There is a yellowish stripe along the front margin of each fore wing. Males usually have two sets of wings. Females either lack wings or have wings that are too small for flying. There are important sensory organs called cerci on the rear-most segment of the body.
At first, many cockroach species appear similar to each other, but have distinguishing characteristics when examined more closely. The American cockroach is often referred to as a water bug. It is 1-1/2 inches to 2 inches long. Its flat oval body is reddish brown. It has wings that are fully developed. There are yellowish edges and markings on the exoskeleton. The exoskeleton, known as the pronotum is usually bare or only slightly covered with silky hair.
The Oriental cockroach has an unusual scallop shape which comes from the way the rear, side corners of its abdomen point outward like edges of a scallop shell. It can be confused with American and Turkistan cockroaches because of its general appearance. However, a closer look will reveal distinguishing cream-colored markings behind the head and around the wings.
The male Oriental cockroach is about 1 inch long and has short, rounded wings. The female is larger than the male and can grow to 1-3/8 inches long. The female has very small wing stubs, so it is flightless. The Oriental cockroach is black or very dark, reddish brown. It is often called Black roach, Black beetle, or water bug because of its dark color and hard body. Another name is Asiatic cockroach. It is also called Shad roach because its young appear in great numbers just when shad are swimming into fresh waters to breed.
The German cockroach looks shiny and is generally brown or light brown in color. It has long slender legs, long, thin antennae, and wings. The Field cockroach is a species that is often confused with the German cockroach. It is olive in color with a black stripe between the eyes. The Madagascar hisser is one of the largest species of cockroach, reaching two to three inches in length when mature. Unlike most cockroach species, it is wingless.