Digestive System Of Cockroach :
Digestive system of cockroach consists of alimentary canal and salivary glands. Alimentary canal is 6-7 cm. in length. The alimentary canal is divisible into three parts-fore gut or stomodaeum, mid gut or mesenteron and hind gut or proctodaeum. Enclosed between the anterior labrum, posterior labium and the lateral mandibles and maxillae is a small narrow space called mouth cavity. It is in front of opening of alimentary canal. The tongue or hypopharynx lies in this cavity. Fore-gut consists of pharynx, oesophagus, crop and gizzard or proventriculus. Pharynx is dilated, short, narrow muscular tube. The mixed food enters the mouth and reaches pharynx. Both mouth and pharynx possess taste sensillae. Pharynx basically is involved into conduction of food. It joints with a narrow tubular passage called oesophagus. Oesophagus passes through the neck and opens into a sac like structure called crop. Crop is large, highly distensible, pear shaped sac that stores food. It extends upto fourth or fifth abdominal segment. From crop food enters into gizzard to proventriculus. It is provided with a circlet of six chitinous teeth that help to crush the food. Behind the chitinous teeth are, backwardly directed fine chitinous bristles in the grooves of gizzard. These are interconnected with each other and form filter. Gizzard is therefore, an efficient grinding and straining apparatus. Gizzard marks the end of fore-gut.
 |
| Cockroach-Digestive system |
Mid-gut (Mesenteron) consists of ventriculus of stomach and eight hepatic caeca. Hepatic caeca are eight thin, transparent, blind tubules arranged in a whorl or rosette fashion in the anterior part of the stomach. They secrete digestive enzymes. Ventriculus or stomach is a short and narrow tube of uniform diameter. It is concerned with digestion of food. The mid-gut is the major organ of digestion and absorption.
 |
| Cockroach-T.S. of Gizzard |
Hind-gut consists of ileum, colon and rectum. It is slightly broader than the mid-gut. At the junction of mid-gut and hind-gut is present a ring of around 150 yellow thread like blind-Malpighian tubules which are excretory in nature. Their product uric acid is poured into short and narrow ileum. Colon is coiled and wide tube. Rectum is the last part of the hind-gut. Rectum opens to the outside by anus which lies below the 10th tergum. Cockroach has two salivary glands, one on each side of crop. Each gland has two glandular lobes and a receptacle or reservoir. Glandular lobes consist of several irregular, white coloured lobules which are provided with collecting ducts. They secrete saliva. The two ducts of two salivary glands unite and form a common salivary duct.
 |
| Cockroach- Salivary Glands |
A thin walled transparent beg like structures called salivary receptacles store saliva. The common salivary receptacular duct runs below the oesophagus through the neck and opens at the base of the tongue or hypopharynx. Under overcrowded condition, the animal has the tendency of even eating its own king. It is called cannibalism.