You may have heard the rumor that cows have more than one stomach. Well, that’s not entirely true. While a cow’s stomach is quite distinct from a human’s, it nevertheless has only one.
The Four Parts of a Cow’s Stomach
A cow basically has four stomachs rolled into one. This is because all four compartments of their stomach do something special. The rumen, the first part of the cow’s stomach, holds the recently consumed food for the longest amount of time. The other parts are the Reticulum, Omasum, and Abomasum.
Here’s what each part of the cow’s stomach does:
- Rumen: Bacteria break down a lot of the food that enters this first part of the cow’s stomach. However, because the cow has dined on grass, it takes extra work to break down the food entirely.
- Reticulum: The partially broken-down meal heads into the reticulum next. There, it promptly gets mixed in with the cow’s saliva. This mixture is called cud, which travels back into the cow’s mouth to be re-chewed.
- Omasum: When the cow has swallowed its cud, the food skips the first two chambers it has already visited and goes straight into the omasum.
- Abomasum: The abomasum is the final chamber of the cow’s stomach. Here, microorganisms do the last bit of labor towards digestion before the food heads back out the other end of the cow.
Other Animals With Multiple Stomach Compartments
When it comes to their eating and digestive behaviors, cows fall into the category of ruminants—plant-eating mammals that gain nutrients via the fermentation process (often due to the action of microorganisms) of their specialized stomachs prior to digestion.
However, cows aren’t the only ruminants out there. Other animals with similar digestive processes include goats, sheep, deer, moose, elk, and buffalo.
Another type of animal that has multiple-chambered stomachs is the camelid, which includes camels, alpacas, and llamas. The camelid’s stomach only has three chambers, but it works similarly to the ruminant’s.
- C1: This compartment functions much like the rumen.
- C2: This chamber acts much like the reticulum.
- C3: This chamber is comparable to the abomasum.
There is a sperm whale that has a four-chambered stomach that’s quite similar to the ruminant’s. However, it works a little bit differently than a cow or a deer’s stomach. If you study the sperm whale’s stomach, you’ll find a:
- Forestomach: This is a chamber consisting of thick muscle that crushes the food the whale eats. (The whale needs this chamber because it has only one row of teeth, which makes it difficult to chew down larger prey.)
- Main Stomach: Digestion takes place in this chamber. The whale can’t digest squid beaks, which it usually vomits up from here. However, some beaks do make it further into the stomach.
- Pyloric Stomach: When food reaches this chamber, it is mixed with pyloric acid and flushed into the small intestine where nutrients are absorbed.
- Pylorus: Also called the hindgut, this chamber is the last part of the stomach that the food flows through before heading out the whale’s body.
Organisms have vastly different stomachs that have evolved to digest the specific foods they eat. If humans lived on raw squid or grass, we might have a four-chambered stomach as well.