A particular smell, or taste, or the sound of a Nickleback song...
In the right circumstances, any of these things might trigger your gag reflex -- or worse,
your emetic reflex, otherwise known as an epic case of cookie tossing.
For humans, gagging has been a very handy strategy for not choking to death -- especially
for babies, who often literally bite off more than they can chew.
And puking might not be pleasant, but it can be a useful way to get rid of bad stuff in
your system.
Despite its usefulness, not all animals gag -- or vomit. But they do have other handy
tricks to compensate.
Spoiler alert: some of them are kind of gross.
Horses, for example, can’t really vomit, because of the way their digestive system
is arranged.
You’re probably familiar -- though hopefully not too familiar -- with how puking works
in humans.
It normally starts with a gag reflex, which constricts the back of your throat.
Repeated constrictions then trigger contractions of your abdomen that force stomach contents
back into your esophagus.
This eventually propels your lunch out of your mouth and hopefully away from any friends
or loved ones.
Horses can’t really do that whole forcing-food-up-the-esophagus thing, though, because of their esophageal
sphincter. That’s the valve that makes sure food stays in your stomach once you swallow
it, and it’s much stronger in horses.
Plus, the angle between a horse’s esophagus and its stomach is a lot like a bend in a hose.
Vomiting builds pressure on the stomach side, and to alleviate it you either have to unbend
the hose by re-arranging the horse’s insides, or try to add enough pressure to force vomit
through the bend.
But in this case, odds are the animal’s stomach would burst before anything got into
its esophagus.
Which is why, for horses, ejecting toxins via the mouth is very rare.
Instead, they flush them out the back door.
The vast majority of nutrient absorption happens in the horse’s intestines and colon, and
diarrhea is a quick way to clear these organs before they can absorb something that seems
dangerous.
Rats also can’t lose their lunch, partly because of a similar valve problem to horses,
and partly because their muscles can’t physically make the movement that would get food up their esophagus.
Instead, a rat that thinks it’s been poisoned will try to cure itself by eating other things,
a behavior known as pica.
Rats aren’t known for being picky eaters -- except when they’re nauseous.
Given the choice, they’ll ignore soils and pebbles in favour of kaolin, a kind of clay.
The more nauseous researchers make the rats, the more clay they’ll eat, and rats given
anti-emetics -- medications that reduce nausea -- will go right back to eating rat food.
Otherwise known as pizza in the subway.
Clay-eating seems to be a rat’s attempt to self-medicate. Biologists still don’t
know all of the details when it comes to how the clay helps, but the metal ions in kaolin
bond well with some toxins -- meaning that the rat doesn’t absorb them.
Then there are the animals that don’t necessarily need to vomit … but they can, if they want
to. So they use it as a defense mechanism.
Turkey vultures are particularly good at this.
Vultures eat rotten meat, which can contain hundreds of species of potentially harmful
bacteria. So if they had to hurl to get rid of that bacteria, they’d hardly ever be
able to keep a meal down.
Instead, turkey vulture guts are extra acidic, which kills off most of the bad bacteria before
it has a chance to hurt them.
They’ve also evolved a tolerance for certain species of bacteria that can cause massive
die-offs in other birds.
Those bacteria help them with digestion now.
But turkey vultures are still physically capable of vomiting. They just do it on purpose.
Aggressively.
Up to 3 meters.
It’s a super effective strategy.
Most people -- and a lot of other animals -- hate being vomited on.
Plus, turkey vulture vomit can be especially acrid and corrosive. A diet full of decaying
animals will do that.
So if you ever encounter an angry vulture, you might want to back away.
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