[♪ intro] Sadly, there’s no such thing as a white, one-horned majestic horse with magical powers. But even though mythical unicorns are just
fantasy, our world is full of fantastic, one-horned creatures. Some of them are beautiful, and some of them
are kind of creepy, but they’re all pretty amazing. So let’s look at some of our planet’s
real-life unicorns. Now you can’t talk about real-life unicorns without talking about narwhals. You knew we were gonna go here. These things grow a single horn that can get
over three meters long. They’re a type of whale that lives in Arctic
waters, and the horn usually grows only on males—although females occasionally grow
a horn too. It’s this long, spiraling tusk, which is
actually just the narwhal’s canine tooth—except, instead of staying inside its mouth, it erupts
out of the upper-left side of its lip. So it’s not your average tooth, but in some
ways it is pretty ordinary: It’s mostly made of dentine, which is the same hardened
tissue that makes our own teeth. And where we have enamel, the narwhal tusk
is surrounded by a cement-like material called cementum, which makes it really strong. But inside, there’s a layer of pulp full
of nerves, so it’s also super-sensitive. Now the idea of an unprotected, super sensitive
tooth, plunging through Arctic waters might sound uncomfortable, but some researchers
think this sensitivity might actually be what makes the horn useful. They’ve hypothesized that a tooth with a
lot of nerves might help the narwhals sense their environment, and some research seems
to back this up. In particular, a 2014 study found that the
horn appears to help narwhals determine how salty the water around them is. Meanwhile, in 2017, researchers studying drone
footage of narwhals found that they use their horns to whack fish and stun them, making
them easier to hunt. And other researchers have suggested that they
use their horns to break up ice. So the horns may have multiple uses, but scientists
still aren’t sure why they evolved in the first place. So they’ve continued looking for other explanations. And more recently, they’ve suggested that
narwhal tusks may play a role in mate selection. For example, females may look at the male’s
tusks to assess their fitness, or males may use their tusks to pick up environmental clues
that might help them find females that are ready to mate. Males also may use other males’ horns as
a way of sizing them up. But even though they’ve basically got built-in
swords on their bodies, they probably don’t exactly spar, since that kind of motion could
easily break their horns, which ya know, like your own teeth, don’t grow back. Scientists are still exploring all the possibilities,
but if narwhal horns do play a role in sexual selection, that could explain why narwhals
got them, and it’s possible they just ended up being useful for lots of different
things, as unwieldy as they seem! Some real-life unicorns definitely use their
horns to fight, though—at least sometimes. For example, rhinoceroses. Rhinos can have either one or two horns, and
they’re mostly made of keratin, which is the same protein that makes up your hair. But rhino horns are a lot tougher than hair—because
all that keratin is also mixed with deposits of calcium and melanin. Calcium is the same stuff that makes your
bones hard, and it also helps strengthen the horn. Meanwhile, the melanin, which is a pigment,
absorbs UV rays from the Sun and helps keep them from damaging the horn. Male rhinos often use these horns to defend
their territory or compete for mates. But they don’t jump straight into a fight. When another rhino threatens their territory,
they often engage in a ritual where they advance toward each other and stop right when they’re
face-to-face. They then stare into each other’s eyes as
they size each other up. This sounds terrifying. In some cases, they’ll settle the dispute
that way and end the ritual by backing away and wiping their horns on the ground. If that doesn’t work, then a rhino might
charge. Unlike narwhals, though, male rhinos aren’t
the only ones that grow horns. Females have horns of their own, which they
use to defend themselves and their calves from predators. But rhino horns aren’t always for attack
or defense. For instance, when water is scarce, rhinos
will sometimes use their horns to dig through dry riverbeds and find something to drink. On the other side of the animal kingdom, an
insect called the rhinoceros beetle also grows an impressive horn. The horn grows only on males, and it’s made
of hardened tissue from the outer layer of the beetles’ head that grows into a long
tube. There are hundreds of species of rhino beetles,
and their horns vary a lot from one species to another, but some of them have horns that
are two-thirds as long as the entire rest of the insect. Which doesn’t sound like the most aerodynamic
arrangement for an animal that actually gets around by flying. But amazingly, researchers have found that
the horn doesn’t really get in the way. In a 2013 study, they ran models on the Asian
rhinoceros beetle to estimate how much that enormous horn would interfere with its flight,
considering both drag and weight. And they found that even the largest beetles
only needed about 3 percent more energy to fly with their horns than they would have
if needed without it. That seems to be because rhino beetles are
slow fliers, and drag is really only significant when you’re moving fast. Plus, the fact that they’re hollow keeps
the horns pretty light, so they don’t really weigh the insects down. Male rhino beetles use their horns to compete
with other males when they’re looking for a mate. They hang out on trees, at spots where sap
oozes through the bark, which is where females come to feed. Then if competitors come by, the stronger
rhino beetles will pry the others off, so that the site is theirs when the females come by. Speaking of creatures with extravagant horns,
a rainforest bird called the rhinoceros hornbill has one of the flashiest horns out there. The hornbill lives in Asia, and it’s famous
for the golden-red horn, called a casque, that sticks out the front of its head. Weirdly enough, though, the golden-red color
isn’t the casque’s natural hue. It starts off white—but it becomes red over
time as the bird rubs it with a gland under its tail, which secretes colored oil that
the bird lathers all over its casque. The oil isn’t just for looking pretty, though—some
scientists think it helps waterproof the bird’s feathers and protect against infections. Like the rhino, the hornbill’s casque is
made of keratin, but it’s not as sturdy as the rhino’s horn. The inside of it is hollow, so the structure
overall is pretty soft—and the hornbills definitely don’t use it for fighting. Scientists think the birds use the hollow
structure as kind of a bullhorn to amplify their calls so their sound can travel farther
in the rainforests where they live. However, studies on other birds with similar
casques also point to another possibility: that hornbills use their casques to manage
their body temperature by dissipating heat. So, scientists haven’t found a definitive
answer yet, but once they do, it could tell us something about more than just hornbills—because
many dinosaurs also had casques, so understanding the hornbill could help us understand these
extinct creatures too. In a different rainforest on the other side
of the world, a South American bird called the horned screamer has a totally different
kind of horn. As intimidating as the bird sounds, its horn
is more of a wispy thing that sticks out of the top of its head and grows up to 15 centimeters
long. And it’s about as flimsy as it looks. It's made of cartilage, and it’s only loosely
attached to the skull, so it’s pretty wobbly. It ends up breaking off pretty often, especially
when it grows too long. But this horn still has its uses! Research shows that during their courtship
displays, male horned screamers wiggle their heads at females... because like who would
say no to that? Older males tend to have larger horns, too,
so they might signal that a male has survived awhile and would be a quality mate, although
scientists don’t know for sure. And if you happen to be feeling bad for
the screamer for getting such a pitiful horn, don’t worry. The horned screamer is just fine at defending
itself. It’s got sharp, six-centimeter-long bone
spurs on its feet, so when push comes to shove, they know how to battle things out. Speaking of vicious horned creatures, in southern
Africa there’s a venomous tarantula called the horned baboon spider. This roughly 13-centimeter-long spider grows
a horn that sticks out the top of its body and attaches to its so-called sucking stomach. That’s the stomach that sucks in the spider’s
prey after it’s been liquefied by the spider’s mouth parts. And the horn seems to play a role in that
digestive process. It’s made of chitin, which is the hard substance
that’s found in many animals. It typically makes the hard parts of invertebrates,
like crab shells and the exoskeletons of insects and spiders. Scientists think that it may serve to
widen the region where the muscles in the sucking stomach attach to the inside of the
exoskeleton, so they can be used with more force. That would let the spider pump in more food
at one time, letting it return to safety faster. It’s also hollow, though, so research suggests
the horn might also store food to help the spiders survive droughts and other tough
times—sort of like a camel’s hump. Finally, we’ve got a horned creature that’s
actually named after the unicorn itself: the unicornfish. It lives in a range stretching from the East
Coast of Africa to Hawai’i, and although the name “unicornfish” technically refers
to the entire genus of fish, only some of them have the horn that they’re named for. The horn is a bony protrusion that actually
looks like something in between a horn and a really long nose. And scientists can’t seem to agree what
it’s actually for. It doesn't seem to be used for fending off
aggressors, since the fish have sharp scales on the sides of their tails for that. Some scientists think that it plays an aerodynamic
role—that it lets larger fish cut through the water more easily—because a few studies
have found that it’s generally the large and slow-moving fish that have the horns. The fish that are naturally faster don’t
seem to have it. Meanwhile, other researchers think that it
might be used for finding a mate. But rather than showing off the size of their
horns like some other horned animals, research shows that unicornfish may be showing off
the color of its horn. A 2007 study showed that during courtship,
males change the color of their horns from a muted neutral color to alternating bright
colors like white and blue, which may either be to impress females or signal to fellow
males that they’re more suitable mates. So the world of one-horned creatures is incredibly
diverse. But one thing they all have in common is that
their horns aren’t just spectacular—they’re also useful. And that seems to be what separates these
from the mythical, one-horned horse: The horse just doesn’t have a reason to have a horn—even
if a horse were born with one by accident, it probably wouldn’t have given the horse
any genetic advantage, so it wouldn’t stick around. But we're not saying nowhere in the universe did some horse-like thing find a use for a horn coming out of the top of its head. And so, if I may editorialize and just say the 8th creature on the list is the unicorn that definitely exists somewhere, because the universe is, as far as we know, infinite. Still, even if the unicorn is just a fantasy,
there are plenty of amazing one-horned creatures out there in the world that are completely real. And with all of this in mind, here in the studio we decided it would be really cool if we made a bunch of stickers of awesome, weird, unicorn-like things that actually exist. So, we're making that. And here they are. And you can order them at DFTBA.com [♪ OUTRO]
