The tube extending from mouth to anus is called alimentary canal. The alimentary canal of the grasshopper is divided into three parts. Stomodium, mesenteron and proctodeum.
1. Stomodium: The part from the stomata to the gizzard is called the anterior alimentary canal. It consists of six parts. These are:
(i) Mukhashidra: The openings in front of the alimentary canal are called mukhashidras. Food enters through it
(ii) Oral cavity: The part enclosed by the oral cavity after the oral cavity is called oral cavity. Food is mixed with saliva in the mouth. It takes the food from the mouth to the pharynx.
(iii) Pharynx: The small, muscular, narrow and cylindrical part located behind the mouth is called pharynx. Through this, food enters the esophagus.
(iv) Esophagus: The narrow, long and cylindrical part after pharynx is called esophagus. It is covered by a thin wall. It transports the food to the crop.
(v) Croup: Esophagus swells to form a sac-like croup. It is thin walled. Food is temporarily stored in it. Food digestion starts from here. Dr. Siddiq Publications
(vi) Gizzard or proventriculus: The posterior extension of the crop is called gizzard. It is a thick, muscular and triangular sac. Its wall is made up of tough, thick and circular muscles. The anterior part of the gizzard is called the armarium and the posterior part is the stomodium captica. Armarium wall folded longitudinally to form six leaf-like teeth. There is a pad-like layer behind the teeth. These leaves have fine bristles or hairs. Longitudinal folds contain bristles in deep pits. Gizzard teeth crush food. Bristle or Rome serves as strainer. Kapatika prevents reverse flow of food.
2. Middle alimentary canal or mesenteron: The part from gizzard to proctodeum is called mesenteron. The junction of the gizzard and the mesentery is called the cardia. The mesentery is called the stomach. The anterior and posterior ends of the stomach have muscular rings or sphincters. It is short and syntactic. It arises from the endoderm and is covered by the peritrophic membrane. The peritrophic membrane prevents food from sticking to the intestinal wall. It protects the intestines from damage. At the junction of the anterior and middle alimentary canal are 6 pairs of hepatic or gastric sica. Hepatic caeca are long, hollow and twisted. Stomach holds food and digests food. Hepatic cica helps in food absorption. Dr. Siddiq Publications
3. Proctodaeum: The posterior part of the middle esophagus is the posterior esophagus. There are 10–15 Malpighian ducts at the junction of the middle and posterior alimentary canals. The posterior alimentary canal consists of four parts. Ileum, colon, rectum and anus. Dr. Siddiq Publications
(i) Ileum: Ileum is narrow, short and tube like part. Its inner wall is furrowed and folded. These folds act like eyelids. Ileum digests food and absorbs nutrients.
(ii) Colon: The long irregular portion next to the ileum is called the colon. The diameter of the colon is greater than that of the ileum. It absorbs food.
(iii) Colon: The most posterior part of alimentary canal is called colon. It is swollen and thick-walled. Its inner wall has 6 folds. These folds are called rectal papillae. It absorbs excess water, mineral salts, amino acids etc. from stool. It also stores the undigested part of the food.
(iv) Anus: The opening at the end of the rectum is called the anus. It removes waste food from the body.