Cockroach - Digestive System

The alimentary canal of Periplaneta is divided into foregut, midgut and hindgut, each with distinct functions described in NCERT. The gizzard, or proventriculus, is a muscular part of the foregut whose inner wall is lined with thick cuticle folds forming six highly chitinous plates or teeth; these grind the food that has been stored and partly softened earlier. The crop is a sac-like dilation of the foregut used mainly for storing food, not for grinding, so it does not bear teeth. The hepatic or gastric caeca are finger-like glands located at the junction of the foregut and midgut that secrete digestive enzymes; they aid chemical digestion rather than mechanical grinding. The colon is part of the hindgut concerned with water reabsorption and waste handling, far removed from the grinding stage. As stated in NCERT Class 11, Chapter 7 (Structural Organisation in Animals), the gizzard grinds the food with its chitinous teeth. A sequence check along the gut confirms that mechanical grinding precedes midgut digestion, matching only the gizzard.