Question

Describe the alimentary canal of a cockroach and its interaction with mankind.

Answer 1

Hint: The alimentary canal which is a part of the digestive system is a continuous food passage through the body from mouth to anus.

Complete answer:
Cockroaches are insects belonging to the phylum Arthropoda. They are present in abundance throughout the world, living in a wide range of environments including tropic and subtropic. They are omnivorous in their food habit.
The digestive system of cockroach consists of an alimentary canal (also known as gut) and digestive glands are differentiated into three regions: foregut, midgut, and hindgut;
1. Foregut- The foregut is composed of the mouth, pharynx, oesophagus, crop, and gizzard. Here, in this region food is masticated and tasted. The mouth leads into a tubular pharynx which further leads to a tubular passage known as the oesophagus. Then the oesophagus opens into a sac-like structure i.e. crop which stores the food. The crop is further followed by a gizzard which helps in the grinding of the food particles and it is lined by the cuticle.
2. Midgut- It is lined by columnar, glandular epithelium, which is composed of messentries and comprises the whole stomach. A thin peritrophic membrane formed across the food particles which protects the cellular lining from injury in the midgut. Rings of six-eight tubules i.e.hepatic or gastric caeca are present at the junction of foregut and midgut.
3. Hindgut- Hindgut is composed of ileum, colon, and rectum, which is a coiled-structure. There is a ring of yellow-colored thin filamentous Malpighian tubules present which helps in the excretion.

Cockroach interaction with mankind:
Cockroaches are much more damaging to mankind, these cockroaches feed on food items such as rotten food, on dead organisms then they also invade the fresh food items. If these contaminated food items because of cockroaches consumed by humans then it can cause dangerous diseases. They can also work as a carrier for different disease-causing microbes such as bacteria and spread various diseases, so they are considered as pests.

Note: Gizzard contains six chitinous cuticular teeth which crush the food particles and serves as a grinding chamber. Midgut serves as the main site for food digestion and assimilation.