Describe digestive tract or alimentary canal of cockroach with diagram.

$\rightarrow$ The alimentary canal of cockroach is complex. It is divided into three regions - Foregut, Midgut and Hindgut.

$\rightarrow$ * Mouth : The mouth opens into a short tubular pharynx. There are mouth organs present in mouth.

$\rightarrow$ 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.

$\rightarrow$ 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.

$\rightarrow$ The part fill gizzard forms foregut. Gizzard open in midgut. Gizzard helps in grinding the food particles by teeth present in it.

$\rightarrow$ The lumen of foregut and midgut is covered by cuticle.

$\rightarrow$ 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.

$\rightarrow$ 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.

$\rightarrow$ The hindgut is broader than midgut and is differentiated into ileum, colon and rectum.

$\rightarrow$ The rectum opens out through anus.