Question

Describe the structure of the leg of a cockroach.

Answer 1

Hint:- Cockroaches are included in class Insecta of phylum Arthropoda. They are brown or black bodied animals. Major body parts of a cockroach include long antennae, legs and a flat extension of the upper body wall that covers the head. They are nocturnal (night loving) omnivores that live in damp places found throughout the world.

Complete Answer:- The body of the cockroach is segmented. It is divided into three distinct regions – head, thorax and abdomen. Their body is covered by a hard chitinous exoskeleton (brown in colour). Their head is triangular in shape and it lies anteriorly at right angles (hypognathous condition) to the longitudinal body axis. It is formed by the fusion of six segments and shows great mobility in all directions due to the flexible neck. Head is connected with thorax by a short extension of prothorax (initial part of thorax) known as the neck. Thorax of a cockroach has three segments- prothorax, mesothorax and metathorax. One pair of legs are present on each segment of the thorax. So there are a total of three pairs of legs in a cockroach.
A cockroach has a very complex structure of legs. Each leg has five segments named as- coxa, trochanter, femur, tibia and tarsus. Segment coxa is the broadest segment. It is followed by segment trochanter. Trochanter is a smaller segment. Then a long segment femur is present which is further followed by the longest segment called the tibia. Tarsus is made up of five small segments called tarsomeres and the last one is called pre tarsus.
Each pre tarsus bears one pair of claws and large adhesive pads called arolium or pulvillus. Cockroaches move on the smooth surface by the help of arolium and on the rough surface by the help of claws. Small adhesive pads present at the junction of tarsomeres are called plantuli. A cockroach climbs on the wall by the help of plantuli and arolium.

Note:- All the legs in a cockroach are identical in structure. Tarsus is the only segment in the leg of a cockroach which itself is a segmented structure. Small tactile seats are present on each segment of legs. They serve as touch receptors for the cockroach. Cockroaches are pests because they spoil food and contaminate it with their smelly excreta. They can transmit a variety of bacterial diseases by contaminating food material.