Question

Digestion is the means by which animals use secretions to break nutrients down into units that can be absorbed and used by the animal. Starting with an animal of your choice, discuss how its digestive system could evolve over generations to become specialized to digest and assimilate a completely different diet. For example (which you can’t use), what would have to happen to the anatomy and physiology of a hummingbird to change it from a nectar-eating bird into a carnivore?

Could anyone help me how to approach this topic and throw out some ideas? Only sharing ideas that may or may not contribute to my own individual answer is okay. Thx :) Like the process of how to collecting information, or how I tend to organize my thoughts, etc.

Answer 1

Solution:-

Animals have evolved different ways of digestion because the food consumed by them varies .

Gastrointestinal cavity: it is a opening which serves as a mouth and waste excretory pathway.Ingested material enter the mouth and passes through a narrow cavity .cells in the cavity secrete digestive juices that break down the ingested material.

Eg : gelly fishes.

Alimentary canal: its an advanced system consisting of a tube which has mouth and excretory path at the end .The ingested food is passed from esophagus and is stored in the organ called the crop. Then the stored food passes to the gizzard where the food is churned and is digested . The churned and digested food travels to the intestine where the nutrients are absorbed and waste is eliminated through feaces . There feaces have a given a specialized term called casting .

Eg : earth worm

Vertibrate digestive system :

There digestive system is more complex because they have a diverse dietary need . Such an animal may havw a single stomach or various compartmental stomach for digestion . Birds have evolved a way and pathway for digestion where the can digest food by uptaking or ingesting non masticated or non chewed food but humans can only undertake digestion of all those foods which have been chewed and churned properly .

Most humans has a monogastric unit of digestion which means they have a single stomach which has been used for digestion and they use many enzymes and digestive juices and many different organs are used to undertake digestion of different food particles .since humans have different component in his / her diet therefore it has to be digested in different organ and compartment of the body .

Avian digestion: birds have a very simplified digestive system , as birds have no theeth they just have beaks and the variety in beaks is due to the availability of different seed types to the bird.

Bird are considered as a faslty digesting organism and haves a very high metabolic rate which helps in fast and effecient digestion which provides bird with energy to fly high and have a very low weight ( body ).

The bird stomach is two chambered one chamber is called the perventriculus that secretes and produces gastric jusices and other chamber is called the gizzard where the food is stored , soaked and mechanically grounded.

Abosorption and digestion takes place in interstine chemically and the undigested food is excreated out in the form of pellets through cloaca