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Stomach Differences in Animals

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Think every living thing on this earth has just the one stomach and that's it? Well think again. Some of the most well known beings you can think of possess more than that. Can you guess which? I’ll help you out.



The definition for this is an animal with only one simple stomach and no compartments. These animals include humans, dogs, horses, rabbits, pigs and rodents. These types of stomachs contain enzymes or peptides within the stomach that help breakdown proteins and starches but not fiber (indigestible portion of food derived from plants) or cellulose (the main component of plant cell walls).

Types of Monograstrics:

  • Omnivores (eat animals and plants)- humans, rats, pigs
  • Herbivores (eat plants)- Horses and rabbits
  • Carnivores (eat animals)- lions, tigers, dogs and cats

Monogastric Tidbit:

  • Though cellulose is hard to breakdown in the human stomach it is beneficial as a bulking agent for feces because it adds bulk and water to stool allowing for easy passage.


This digestive system, you may have guessed it, is directed more toward birds. But what you might not have guessed is that they have 2 compartments within their stomach. In their first stomach called the proventriculus, the food mixes with digestive enzymes and hydrochloric acid. Then you have the ventriculus, better known as the gizzard. In this chamber, the gizzard, acts the way teeth do for you and I. When birds take in some of their food they also take in stones or grit. The stones act as teeth and grind up what the bird has eaten, making it easier to digest. As time goes on the stones in the stomach get smaller and smaller until they are able to leave out of the stomach as well.

Avian Tidbit:

  • Other animals with gizzards are alligators, crocodiles and fish.
  • Birds have what is called a crop. It holds their food before it goes to their stomach. It can be helpful when a bird has to eat and run due to predator danger. They can eat, store their food in their crop and it can later move onto the first stomach.


Ruminants have the capabilities of regurgitating, chewing and re-swallowing their meals in order to digest it more easily. Examples of these animals are cows, sheep, deer, giraffes and moose. These creatures have a count of 4 compartments in their stomach. Holy cow! That’s a lot of digesting. The excess stomachs make for easier digestion of the roughage and plant life that animals eat. The process of the 4 compartments goes like this:

  • Things that can’t be digested or passed through are first collected in the Rumen which is the largest compartment. It contains bacteria, protozoa and fungi.
  • Fibrous materials are broken down in a fermentation storage area in the stomach within the Reticulum.
  • In the Omasum, excess water is absorbed from the broken down material of the Reticulum.
  • Lastly, the enzymes in the Abomasum break down proteins and starches.
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Ruminant Tidbit:

  • Before the age of 1 a magnet is fed to a cow. Once in, it settles in the rumen or reticulum. It’s put there to attract any pieces of metal that the cow may eat to prevent the metal from embedding in the stomach. The magnet stays in the cow for life.
  • The food that a ruminant regurgitates out to re-chew is call cud.


This type of digestive system handles the difficult task of breaking down the sugar molecule, cellulose, by only using 3 compartments instead of 4 like a true ruminant. They lack the rumen stage but contain the reticulum, omasum and abomasum. Plus, as to where ruminants regurgitate their food pseudo-ruminants do not. To make up for this step their system has a very large cecum that handles the breaking down of roughage that the rumen stage in the ruminants would have taken care of. The cecum sits between the small and large intestines. It digests and ferments the plant cells pseudo-ruminants eat. Camels, llamas and alpacas fit in this category.

Pseudo-Ruminants Tidbit:

  • Though rabbits and horses are known to have monogastric digestive systems they also have pseudo-ruminant tendencies due to them having large cecums as well.

Though some animals have more than one compartment within their stomachs it is not to be confused with saying they have multiple stomachs. Whether an animal has multiple compartments within their stomach or a single stomach they all have the same goal. They all have the objective of enabling the stomach to digest food into smaller pieces. Without them we would all be unable to rid the food we ingest out of our stomachs properly.

Check out the facts for yourself:


Ad on May 03, 2018:

I've been trying to find scientific information about stomach differences in small and big cats. It's said that wild cats have to eat multiple times per day because of their stomach not being able to stretch. Is that true for all small cats including the lynx? I'm "guessing" the cougar eats more like a big cat even though it can't roar.

Could you, or a viewer, elaborate on this?

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