We’re answering ten questions as quickly as we can in this episode of But Why. Why do onions make you cry? How do hummingbirds hum? Why do flamingos stand on one leg? Do moths have veins in their wings? Do cats that share a home have the same meow? What was the first book? How do libraries get money if people borrow books for free? Why do people have fidget spinners? Why can't my stuffed animal get wet? And how do pigs poop? Can we do it all in 20 minutes?!
Actually, scientists aren't really sure, but one prevailing theory is that they stand on one leg to save energy. "Flamingos all spend a great deal of time standing on one leg simply because it enables them to perform some of their less active behaviors without the need to keep balancing themselves by using their muscles," said Paul Rose, a flamingo researcher at the Wildfowl and Wetlands Trust at Slimbridge in the United Kingdom. "If you balance without using your muscles you actually don't expend any energy whatsoever in keeping still. The weight of the flamingo pushes down through the bones and the joints in the bird's legs and that means it can stand very energy-efficiently for an incredibly long time."
For humans, standing on one leg actually takes more energy, but for flamingos it's easy! They don't wobble like a person would. Rose says flamingos spend a lot of time resting or loafing, as it's officially called, so they can save up energy for feeding or taking care of their babies. But Rose says another theory is that flamingos stand on one leg to stay warm when they're in cold water.
Flamingos are unique in lots of ways, but standing on one leg isn't one of them. Lots of birds stand on one leg, we just notice it more with flamingos because they're so big pink!
Pigs poop the same way we do and for the same reasons. Pigs eat a lot of different things and as their bodies process all of the good stuff, the vitamins and nutrients their bodies need to function, there's also some stuff that's not absorbed by the body. It's basically garbage and your body needs to take out the trash. After you chew your food, it goes down into your stomach where some acid helps break it up into even smaller pieces. And then food travels through the intestines. The intestines are like a long skinny tube that twists and turns inside your body. As the food goes through the intestines, those good nutrients are getting sucked out. And by the time the food gets pushed through to the end of the intestines, what's left is poop. Just like you, when that food has made it all the way to the end of the line, the pig gets a sensation that it needs to go to the bathroom and out comes the poop.
One big difference though: pigs don't bother finding a toilet. They just go where they please!
Listen to the full episode for answers to more questions.