So, I’ve wondered for awhile why carnivores have shorter guts than omnivores.
You see, the longer an animal’s gut is, the more capable it is of digesting plants. That’s why herbivores have much, much, much longer digestive systems than omnivores. (Cows have four stomachs, for example.) Meat is easier to digest, which is why herbivores can eat meat (and most do!), but carnivores can’t eat plants.
“What is the advantage,” I wondered, “to being a pure carnivore? Wouldn’t it be more advantageous to any species to be capable of eating plants, just in case prey became scarce?”
Well, it turns out there’s an advantage to having a shorter digestive tract!
The shorter the gut, the less time food stays inside the animal. The less time food stays inside the animal, the less time pathogenic microorganisms have to reproduce and spread through the animal.
On top of that, the shorter the digestive tract, the lower the stomach acid pH can be (because it takes a lot of extra work for a body to protect itself from stronger stomach acid). The stronger the stomach acid, the more bacteria get killed in the stomach.
So a short digestive tract not only sends pathogenic microorganisms out sooner, giving them less time to multiply, it also makes it possible to have a lower stomach acid pH, making it much easier to kill them.
In fact, if the pH is really low, the animal can even digest pathogenic microorganisms as a bonus energy source. For vultures, botulism is food!
So that’s why scavengers (like vultures and hyenas) are usually carnivores. Essentially, those species chose to give up being able to eat plants in order to be able to eat pathogenic bacteria.
It’s awesome that that tradeoff is worthwhile, and in fact extremely valuable to all the other animal species in an ecosystem. In a sense, you could say that pure carnivores are eating other predators (the teeny tiny ones), and therefore protecting their prey just as much as they are killing them. Which explains why apex predators and scavengers, who tend to be pure carnivores, tend to be keystone species, and therefore essential to keep an ecosystem working.
I thought that was pretty cool.