Answer: Four-Chambered Stomachs

A peculiar stomach structure is what sets ruminants apart from other animals. We humans, and nearly all other animals, have a single chamber stomach system (monogastric). We mash up and swallow our food, it is significantly worked over by our stomach acids, and it is passed along through our digestive system.

Ruminants, however, have highly specialized stomachs comprised of four chambers and a much more complex digestive system. These animals have evolved complex stomach systems in order to maximize the nutritional value of their plant-based diets. Each chamber of the stomach is responsible for helping break down and separate the plant matter, and the chambers host a diverse range of bacterial flora (as well as some protozoa, fungi, and yeast) that assists these animals in digesting even the parts of the plants, like the fiber, that are indigestible to humans and most other mammals.

There are roughly 150 species of ruminants, both wild and domesticated, including cattle (perhaps the best known ruminant), as well as goats, sheep, deer, antelope, and giraffes.