Describe digestive tract or alimentary canal of cockroach with diagram.

Explanation

The alimentary canal of cockroach is complex. It is divided into three regions - Foregut, Midgut and Hindgut. Mouth : The mouth opens into a short tubular pharynx. There are mouth organs present in mouth. Pharynx, lead to a narrow tubular passage called oesophagus. This in turn opens into a sac like structure called crop used for storing of food. The crop is followed by gizzard or proventriculus. It has an outer layer of thick circular muscles and thick inner cuticle forming six highly chitinous plate called teeth. The part fill gizzard forms foregut. Gizzard open in midgut. Gizzard helps in grinding the food particles by teeth present in it. The lumen of foregut and midgut is covered by cuticle. A ring of 6-8 blind tubules called hepatic or gastric caecae is present at the junction of foregut and midgut, which secrete digestive juice. Midgut opens into hindgut. At the junction of foregut and midgut is present another ring of 100-150 yellow coloured thin filamentous Malpighian tubules. They help in removal of excretory products from haemolymph. The hindgut is broader than midgut and is differentiated into ileum, colon and rectum. The rectum opens out through anus.