Alimentary Canal in Cockroach

Alimentary Canal of a Cockroach and Their Functions

The digestive system or alimentary canal of a cockroach and their functions is given below– 

Foregut – The digestive system starts with the foregut comprising the mouth and surrounding parts of the mouth. The cavity of the mouth is known as pharynx. It extends in the form of an oesophagus which is a thin wall like structure. Further extending of the canal is known as the crop which is a similar structure like the oesophagus. The opening of the crop is known as proventriculus/ gizzard which is an organ that is muscular in nature.  There are two glands of salivary duct in cockroaches. Salivary glands have branches which secrete into different branches which flow through to a combined passage. There is a bladder-like structure in which the salivary receptacle is in place for both the salivary glands. They are mainly placed for storage of the salivary secretions. Both the receptacles are combined or common passage which is rectangular in shape and is opened to salivary passage. Chitin has its lining to the entire foregut. For grinding the food, the chitin creates the proventricular teeth and plate. 

Midgut – It creates the real gut which is Mesenteron and comprises the whole stomach/ventriculus.  It has mainly 6 pairs of gastric caeca at the joint of gizzard and stomach. In the interior end of the stomach, they form rings – like the style and pouch – like structure. The anterior lobe of each caeca expands above the proventriculus but the posterior lobe extends upto ventriculus. Various digestive juices flow into the stomach which is made by the caeca secretion.  Midgut is lined by a peritrophic membrane and it’s not by a cuticle. This membrane saves the stomach wall from any damages and simultaneously is fully passable for enzymes and food digested.

Hindgut – It consists of a coil- like structure which comprises the anterior ileum, middle colon and posterior rectum. Posterior rectum has has an opening to the exterior via the anus. Its lining is formed by the cuticle. There’s a large number of tubules which are long in length and are known as Malpighian tubules right at the joint of stomach and ileum. 

Digestion part in cockroach

Digestion in cockroaches begins first at the mouth where parts like mandible and maxilla help them chew the food. Salivary carbohydrates, which is the part that digests food to a partial extent, lubricates saliva juice which helps them swallow their food.  The food then moves to the esophagus and then into the crop. It’s the point where the food is masticated and stored temporarily. The next point where the food moves is at the gizzard where the grinding takes place. At the stomach and gizzard is present a valve which is known as stomodeal valve right at the joint. 

The emesis of food would be prevented by a valve while ensuring a smooth passage of food into the stomach. Digestive enzymes treat the food which enter the stomach created by gastric caeca. There are enzymes which include invertase, amylase, tryptase, maltase and lipase. However, residual fats, proteins and carbohydrates would be absorbed here. 

Conclusion

Cockroaches consist under the Blattodea order. They originated during the carboniferous period. However, it lacked the internal ovipositors of modern roaches. Also, they have special adaptations which are like sucking mouthparts like other true bugs and are considered to be much more generalised insects. Tropical cockroaches are considered to be a larger species and are common and hardy insects capable of tolerating heat and a wide range of climates.

  From the above-written characteristics, we can conclude the complex digestion structure in cockroaches.  The system comprises the 3 parts which are foregut, midgut and hindgut. Crop in the foregut is used to store food and is present in the forefoot of the alimentary canal. Gizzard helps in grinding the food.Cockroaches being an insect possess an open circulatory system. An open type circulatory system is the process where the blood flows into the blood spaces and the organism is without the respiratory pigment known as the haemolymph.  They are therefore considered as the scariest organism though because of their looks but they are much more damaging to humankind. They feed on various dead organisms as well as rotten food and then later on they invade fresh food as well. It also spreads diseases considered to be the carrier of it causing organisms such as bacteria.