Digestive systems of herbivores and carnivores

How does the digestive system change between species?

Depending on the diet of each species, the length, function and size of different regions of the digestive system varies

What are insectivores?

Animals which feed on insects and worms

What is the digestive system of insectivores?

Insects are largely made of chitin and protein, which is easily digestible material. They have a short gut as the products of digestion are absorbed well

What is the digestive system of non ruminant herbivores?

These feed on plant material with a high fibre and cellulose content, which is difficult to digest. Bacteria and archaea are present in the caecum (part of the large intestine) which can digest cellulose and produce protein. Bacterial digestion occurs after the ileum, so the products of bacterial digestion aren’t absorbed. Some animals like rabbits eat their faeces to absorb the extra nutrients. Others like horses do not so have less effective digestion and absorption.

What is the digestive system of a carnivore?

Meat is made mostly of protein and fat, which is easy to digest and absorb. The digestive system is shorter and the stomach is relatively larger to enable increased digestion of protein

What is the digestive system of a ruminant herbivore?

They have a four-chambered stomach; the rumen, reticulum, omasum and abomasum. This ensures that food is efficiently digested as much as possible since ruminants feed on cellulose and fibre rich plant material which does not provide many nutrients considering the volume of food consumed

What are the parts of a ruminant herbivore’s digestive tract?

Mouth, oesophagus, rumen, reticulum, oesophagus, mouth, oesophagus, omasum, abomasum, duodenum, ileum

What happens in the mouth of a ruminant herbivore?

Food is ingested and chewed ready to be swallowed

What is the function of the oesophagus of a ruminant herbivore?

It has voluntary muscle to enable reverse peristalsis so that partially digested food can be returned to the mouth for a second chewing

What is the function of the rumen of a ruminant herbivore?

It is the fermentation chamber for chewed cud under anaerobic conditions (which releases methane to contribute to the greenhouse effect). Bacteria are present to convert cellulose to sugars with the enzyme cellulase. Sugars become organic acids (providing an energy source), ammonium salts become proteins, and bacteria synthesises vitamin B. Ciliates in protoctista form are also present to feed from the bacteria

What is the function of the reticulum in ruminant herbivores?

It receives fermented grass from the rumen. The mixture is formed into balls (the cud) which is regurgitated into the mouth for further chewing

Why do ruminants rechew their food?

It allows them to further break down the cellulose fibres for extra mechanical breakdown of cellulose cell walls and releases the contents of bacterial and ciliate cells which were introduced from the grass. Grass is mixed with microbes for more effective enzyme action

What is the function of the omasum in ruminant herbivores?

It reabsorbs water (which is very necessary to save water - cows secrete 1.5 litres of saliva per day!). Solidified food passes to the abomasum

What is the function of the abomasum in ruminant herbivores?

It is the true stomach. Proteins are passed here straight from the rumen for digestion. Hydrochloric acid and pepsin digests proteins from grass and bacteria and ciliates to form peptides

What happens in the duodenum of a ruminant herbivore?

The peptide rich mixture of food passes past the pyloric sphincter and completes digestion (along with the ileum) by absorbing soluble products

How do young ruminants digest their mother’s milk?

Milk passes directly from the oesophagus past the three first chambers into the abomasum as milk is high in protein and no other chambers are necessary