Birds do not have teeth but as a substitute, they have horny beaks that demonstrate adaptive radiation suitable for a gastronomic (ability to choose, preparing, and consume good quality food) lifestyle. However, their digestive system should process non-chewable (un-masticated) food. Their keratinized tongue aids the mechanical breakdown of crops. Birds have no teeth, For instance, beaks may have fine edges or sharp, hook-like upper bill or sharp wood pecking points The bird’s stomach has two chambers: the proventriculus, in which the gastric juices perform the digestion of the food particle before it penetrates the stomach of the organism, and the gizzard, where the storing, soaking of food takes places. The undigested form of food material food is regurgitated. The absorption and chemical digestion occur in the intestine and the waste material is discharged through the cloaca.
The digestive system in Non-Mammalian Vertebrates:
In this, the short, wide ciliated esophagus is present. The stomach region consists of fundus and pylorus glands. The progress of extracellular digestion in an alimentary canal was a significant improvement in evolution. It freed large animals from continuous feeding as they were not capable of intake a few large chunks of food, relatively it undergoes intracellular digestion by slowly ingesting many particles small enough to enter cells. It has a short tubular, coiled alimentary canal which is well-organized as it permits food to pass in unilateral direction, transient through different regions of digestive specialization. The alimentary canals serve as functions of receiving, conducting, and storage, digestive and absorbing nutrients, and absorbing water and defecating. Herbivorous mammals need long digestive tracts along with specific pouches to breakdown plant materials. Cellulose, the structural carbohydrate of plants is potentially nutritious foodstuff, composed of long chains of glucose units. The diet of proteins can be more easily digested, therefore, insectivorous as well as carnivorous mammals possess shorter digestive tracts with some specialized compartments.
