Random Biology: 10 fun facts you never knew you cared about

I know this blog’s purpose is to help you learn how to improve your scientific literacy, argue with people who are anti-vaccine, etc… but its other purpose is to talk about the fun side of science. So enjoy some random biology facts below, and become instantly more fun at parties. (And hey, it can’t hurt to check these sources while you’re at it!)

  • Horses can sleep standing up because of something called a “stay apparatus” in their legs.

    Ever rest your weight on one leg and your hip sort of rests in place? You might even be able to “pop” your hip back out of place by shifting your weight around. Horses do that too (video here), but on three legs at once. This happens because of the way the ligaments pull against each other to “stabilize” the leg.
    However, horses must lie down to reach REM sleep; when they’re standing, their muscles can’t fully relax, so they can only doze off. They only sleep about 3 hours per day, 20-30 minutes of which has to be REM.

  • Flamingos also have a stay apparatus… even when they’re dead.


Their body weight pushes its knee into a locked position, and it just hangs out there passively. Scientists even balanced a dead flamingo on one leg, and it stayed up. In fact, flamingos actually use more energy standing on two legs than just one.

  • Male ginger cats outnumber females about 3 to 1.

ginger cat

You’ve probably heard this one before, but here’s why. The gene that causes ginger hair in cats is located on the X chromosome. Like humans, females are XX and males are XY. (If you need a refresher, watch for a quick and dirty crash course on X and Y chromosomes.) The Y chromosome is pretty little and doesn’t usually carry that many genes. Basically, what makes a male is not the presence of Y, but rather, the absence of a second X. (Which is empowering, somehow… but I digress.) Anyway. In male cats, just one copy of the “ginger” gene, which will be on his X chromosome, is enough to make his fur red:


In females, however, they need two copies of the gene, one on each X chromosome. This is because there is another major fur color allele (“uh-LEEL”; basically, a different version of the same gene), which causes black fur:


If the black fur allele is present on the second X chromosome, black patches will show through the red and you’ll get a super cute tortoiseshell instead. But female ginger cats aren’t really that rare, because some of them do get that second ginger allele:


They’re just not as common as the boys. Read more about kitty color genetics here and here.

  • The scientific word for stretching is pandiculation.


Apparently, stretching (and yawning, which is the same basic reflex) helps an animal snap out of a sleep cycle and make itself alert. It’s also a sort of calibration system for our muscles — our body’s way of making sure everything’s well-oiled and maintained.


The leaves of the acacia tree in Africa, for example, release an ethylene gas warning signal when being eaten by giraffes and the like. The signal spreads to surrounding leaves, which respond by releasing bitter tannins (the same chemical that makes bad wine taste… bad). The leaves actually change the way they taste to keep the giraffe from eating them. This is why a giraffe keeps moving as it eats, leaving behind a trail of screaming acacia trees, rather than stripping an entire tree at a time.

Apparently, acacia leaves can go even further and produce enough tannins to actually kill an antelope. Amazingly, giraffes have learned to travel upwind while eating, because those trees didn’t get the memo titled “Everybody turn on your f**king tannins”.

baby humpback whale

Basically, me in college.

  • Snake venom wouldn’t hurt you if you swallowed it (probably).

Close-up Cobra Eye Animal Animal Photography
Most venoms are proteins designed to directly enter the bloodstream (hence the fangs). Thankfully, we have lots of digestive defenses that would break the venom down in our stomach just like any other protein, the same way we digest food. The key is that this would happen long before the venom was able to enter our blood. So unless you have a cut on the inside of your mouth, you should be fine. That being said, if you drink a snake venom milkshake, I’m pretending we’ve never met.

Poison, on the other hand, you definitely don’t want to swallow! It’s designed to be ingested, inhaled, or absorbed through your skin (like my absolute favorite, the adorable poison dart frog). Here’s a great TED-Ed video on venom vs. poison.

  • Your liver can regrow itself even after 75% of it is removed or damaged.

liver lobules
You’ve heard this before, you lush. But here’s why. The liver is made up of individual units, called lobules, that make up a honeycomb-like structure. Each lobule contains all the necessary processes for the liver to function, and can regenerate neighboring lobules if some of them are lost.

In contrast, think of an organ like the heart. Rather than a matrix of many smaller, identical parts, the heart is one big machine with many moving parts working together. If one part is damaged or lost, the rest of the machine can’t function.


Another example is the lung: it’s made up of tiny units called alveoli, but really, it’s basically a big sack of air. If the sack suffers a puncture, the lung loses its most basic function.


Funny enough, humans can also regenerate a few other organs for the same reason that we can re-grow our liver. These include the top layer of your skin, parts of the kidney, the endometrium (that lovely stuff women lose and regrow every month if they don’t get pregnant), and the very tips of your fingers and toes.

  • Alcohol stays on your breath longer than other substances because the smell comes from your blood, not from your mouth.

Ethanol, the chemical that gets you drunk, hangs out in your bloodstream. It’s very volatile, meaning it changes from liquid to gas really fast — in other words, it evaporates easily. So when you exhale, ethanol from your bloodstream which has seeped (or diffused) into surrounding lung tissue leaves your body through your mouth. This is how a breathalyzer is able to estimate blood alcohol levels just by taking a sample of your Four Loko breath.

  • Birds don’t pee.
Skeptical Chicken
No, seriously.

All animals excrete nitrogen as a waste product. But the type of nitrogenous (“nye-TRAH-gin-us”) product depends on the animal and its environment.

There are three types of nitrogenous waste, in order of lowest to highest amount of nitrogen in one molecule: ammonia (1 nitrogen), urea (2 nitrogens), and uric acid (4 nitrogens). These are also in order from least to most concentrated. So ammonia comes out as a pure liquid, uric acid as a solid, and urea somewhere in between.

nitrogenFish, who are surrounded by water all the time, don’t need to worry about retaining water. So they can just spew out ammonia all the time, which takes the least energy. Fish also don’t have to worry about the high toxicity of ammonia, since it’s squirted out into a giant volume of water and quickly spread out (or diluted). Mammals (including humans) excrete urea, which is way less toxic than ammonia and lets us retain a good chunk of the water we drink.

Birds, on the other hand, are flying all the time, so storing water is an issue. Anyone who’s ever carbo-loaded knows that water weight can affect a person. Imagine how important that amount of weight would be to a flying bird. So, since birds can’t drink a ton of water like humans and mammals can, they need a really efficient water retention system.

That’s where uric acid comes in: it takes a fair amount of energy to convert ammonia to that white, chalky goop, but since it’s basically solid nitrogen, they can dump (heh) the maximum amount of nitrogen possible without sacrificing a bunch of water. All waste, nitrogenous and otherwise, is directed to (and excreted from) the bird’s cloaca, the Swiss army knife of animal butts.

Reptiles in dry conditions, who live in the desert where water is a hot commodity, also excrete uric acid for similar reasons.

nitrogenous waste

Pretty neat, huh?

One thought on “Random Biology: 10 fun facts you never knew you cared about

  1. Pingback: Researchers concerned about superbugs found in sea turtles’ bums – UnScienced

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