• But some of them have taken it one step further and developed incredible evolutionary traits.
  • From the blistering desert and a camel's hump to the expansive ocean and a turtles shell or maybe it's a Venus fly traps...trap?
  • It's what's inside these distinctive traits that is truly remarkable.
  • Visit Business Insider's homepage for more stories .

The following is a transcript of the video:

Narrator: From blistering hot deserts to deep blue oceans, from frozen ponds to swampy wetlands, animal species have adapted and evolved in unique ways. Let's take a look deep inside these distinctive animals, and learn what adaptations they've picked up in order to call these harsh landscapes 'home'.

At first glance, a kangaroo's pouch looks like nothing but a built-in baby sling. But if you peeked inside, you'd see it's far more complex than a simple pocket.

It has to be because the joey inside is not your average baby. An adult male red kangaroo can stand over 1 1/2 meters tall and weigh 90 kilograms.

That's larger than a grown man. But the newborns start out the size of jelly beans.

They're blind, deaf, and hairless to boot. After all, they only spend 33 days inside their mom before birth. That's like a human having a baby when she's two months pregnant. So the underdeveloped roo isn't ready to face the harsh Australian wilderness.

That's where the pouch comes in. It's a pocket of skin that acts like a second womb, giving the joey a safe, cozy environment to grow. And, like a pregnant belly, the pouch can stretch to fit the baby as it gets bigger.

It's lined with powerful, but flexible, muscles and ligaments. To keep the joey safe, mom can tighten those muscles to shut the pouch flush against her body, just like pulling a drawstring bag closed.

And it will need the extra space, because over the course of eight months, that bean-sized baby will reach the size of a large house cat. That's thousands of times its birth weight.

That rapid growth is thanks to the pouch's four nipples, which spout milk that contains germ-fighting antibodies to keep the little roo from getting sick.

But that's just the start. You see, the nutrient levels change to meet the baby's needs as it ages. For example, sulfur, a major building block of hair, peaks around three months in. That's the same time the baby starts growing fur.

The best part? Mom can produce multiple types of milk at the same time, each squirting from its own nipple. So she can suckle two babies in different age groups simultaneously.

Another special feature about the kangaroo pouch is that it's lined with sweat glands that release antimicrobial substances, which help protect the baby roos from harmful viruses, bacteria, and parasites.

But there's one more way that pouch's design keeps the joey safe. It's totally hairless, and that skin-to-skin contact keeps the baby warm and cozy. Basically, it's the ultimate nursery.

But nothing lasts forever. Eventually, the joey will need to leave the pouch.

At about 5 months old, it pokes its head out. And a month later, it takes its first tentative steps into the world. There, it will explore for a few short seconds before high-tailing it home.

But as it gets older and bolder, it stays out longer, until eight months in. It's ready to leave the nest, well, the pouch, for good.

What would you do for the power to fly?

How about shedding your skin and dissolving your own muscles? Now, believe it or not, that gruesome process is how caterpillars earn their wings. Here's what you might not know about what's inside a caterpillar's "cocoon."

Contrary to popular belief, this is not a cocoon. Only certain moths build cocoons, which are like a silky sleeping bag that covers the insect. This, on the other hand, is what's called a chrysalis. It's not a sack or a pouch; it's actually the caterpillar's own body.

When it's time for the transformation to begin, the caterpillar's body ramps up production of a hormone called ecdysone, and that causes it to cast off its outer coating, sort of like how a snake sheds its skin. And underneath is a hard shell similar to the exoskeleton of a beetle.

After that, life for the little caterpillar gets oozy. First, it releases enzymes called caspases. These rip apart and dissolve cells in its muscles, digestive system, and other organs. But the enzymes don't quite liquefy all of the caterpillar. They leave key structures intact, like breathing tubes. At the same time, specialized cells called imaginal discs start waking up.

Before the chrysalis stage, these discs were kept dormant by a series of hormones in the caterpillar's body. But once the transformation begins, those hormone levels take a nosedive, giving these discs the opportunity to do what they do best: build a butterfly. You see, each disc contains the genetic recipe to form a different adult body part, starting from the inside out.

After one week, the digestive system of the butterfly is well on its way. And by day 16, the adult's legs, wings, eyes, and mouth are all present and in working order. Now, two weeks is a remarkably short time for all of this to happen, since each imaginal disc starts out with only about 50 cells and must multiply those into thousands just to form a single wing.

And if you checked out the chrysalis around day 16, you might even be able to see those brilliantly colored wings. Because for some species, their chrysalis turns transparent in their final days of metamorphosis.

Now, fully formed, it's time to hit the road. The chrysalis splits open down the center, and the butterfly escapes. Meanwhile, a reddish liquid spills out. That's all the waste the butterfly, ne caterpillar, produced during its stay. Once its wings expand and harden, it's ready to mate, pollinate, and slurp nectar to its heart's desire.

But one of the most interesting parts of all? Research suggests that butterflies and moths can remember their caterpillar days. In one study, researchers trained moth caterpillars to associate an odor with an electric shock, so whenever the larvae smelled it, they'd move away. But even after they transformed into adult moths, they still avoided the scary smell. It makes you wonder what else they could recall from their younger days.

When it comes to deadly predators, plants generally don't come to mind. After all, they're typically at the bottom of the food chain. But the Carolinas are home to one vicious vegetable: The Venus flytrap.

Using its famous trap, it can catch prey faster than you can blink. But what happens next ... inside a Venus flytrap?

Funny thing about Venus flytraps:They don't usually trap flies. In fact, winged insects only make up 5% of their diet.

Sorenson: We really ought to be calling it the Carolina spider trap. Because it's only found in a little piece of the Carolinas, and it mostly eats spiders and ants.

Narrator: But regardless of the species, that bug is going to have a bad day. It all starts when the victim wanders into the trap, possibly lured by the bright-red hue or fragrant scent. Or maybe they're just unlucky.

Sorenson: We think the spiders mostly just blunder.

Narrator: That trap itself looks like an open mouth.It's made of two pads attached to a hinge.

Sorenson: On each one of those pads there are usually three little trigger hairs in a triangle. And those trigger hairs are very, very sensitive to being disturbed.

Narrator: The first time the spider knocks into a hair, it sets off an electrical signal, sort of like the electrical currents in your brain. That signal starts the countdown.

If the bug escapes within 20 to 30 seconds, nothing else happens. That way, the plant doesn't waste energy. But if the bug brushes against another hair ... SNAP! In just 100 milliseconds about four times faster than you can blink the trap slams shut.

Sorenson: The trap rapidly goes from convex to concave on each side, and the long little spikes on the rims of the pads interlock to form kind of a cage.

Narrator: Now, the spider isn't happy with this turn of events. So, it tries to escape, which is exactly what the plant wants.

The more the spider struggles, the more it knocks into the trigger hairs, the tighter the trap closes.And after an hour or two, the trap locks completely.Cells on the edges of the pads secrete moisture, which glues the edges together to form an airtight seal.Suddenly, that trap isn't a mouth anymore.

It's a stomach.Digestive juices flood into the closed compartment, dissolving the spider's soft organs. And the trap's lining sucks up that nutrient-rich slushy.

After about a week, all that's left is an empty husk the spider's exoskeleton.Next, the trap opens and the husk tumbles out.The trap's now ready for its next meal.

But bugs aren't the only food the trap captures.Just like leaves on other plants, the trap's surface contains a green pigment that lets it convert the sun's energy to sugar through a process called photosynthesis.So then, why bother with the bugs?

Well, Venus flytraps live in acidic, waterlogged soil that doesn't have many nutrients.So instead of slurping up nitrogen and phosphorus through its roots, it needs to borrow some from the bugs.That explains why it shares its home with other hungry carnivorous plants like pitcher plants and sundews.

Which means one thing: North Carolina is not a fun place to be a bug.

Narrator: If there's one thing you know about puffer fish, it's that they can do this. When aggravated by a predator, they, you know, puff up. Some puffers, like the porcupine fish, become a bona fide spike ball, moving through the water seemingly out of control.

But if you peer inside a puffer, you'll learn that puffing up isn't the only trait that makes these fish one of the most threatening creatures in the sea.

Contrary to what it looks like, puffer fish are not like balloons. Because what's normally inside them isn't air. It's water.

Elizabeth Brainerd: What they do is they actually take water into their mouths in a big mouthful of water, and then they pump it down into their stomach.

Narrator: That's Elizabeth Brainerd, a biologist and puffer fish expert at Brown University.

Brainerd: And they do that anywhere 10 or 15 times, pump, pump, pump, pump, pump, pump, until they inflate completely, and then they hold it and they'll just be a big, spiny ball.

Narrator: And as you might expect, this requires some pretty sophisticated biology, starting with the stomach. It's made of dozens of tiny folds, kind of like an accordion. These folds are important because when the stomach fills up with water, it can expand without rupturing. And puffer fish expand a lot. Up to three times their size. That's like if an average human man could inflate his waist to a circumference of 3 meters.

But there is a drawback to these amazing skills. Brainerd suspects that puffer fish stomachs have actually lost the ability to digest food, which means their intestines have to do all the work.

Brainerd: You know, given the apparent importance of this defense mechanism, they've given up the advantages of having a stomach where some digestion can start.

Narrator: But the stomach? It's just one of many bizarre features inside a puffer. For example, they have specialized muscles that you won't find in most other fish. Some in their mouth, which pump all that water into their stomach; some in their esophagus, to seal off their stomach like a drain plug once it's full; and some in the base of their bellies, which contract to squeeze out water when they're ready to deflate. But what you won't find inside is even more bizarre.

Brainerd: There are a couple characters that are really helpful in their ability to puff up, and one of those is that they don't have any ribs, and another one is they don't have any pelvis.

Narrator: In other words, puffers are essentially missing bones. And that's a good thing, because otherwise they'd get in the way of inflation. In fact, according to Brainerd, if it weren't for these missing bones, puffer fish would probably have never evolved this way in the first place. And that would be a shame, since puffing up really is a good defense.

Consider one old study in which researchers watched birds go fishing. The birds caught 11 puffer fish, but they dropped nearly half of them because the fish started to inflate. But what's more surprising is that the birds left with empty beaks might have been the lucky ones.

Because puffers have another, more potent defense up their sleeves. Their bodies are laced with a neurotoxin called tetrodotoxin. It's up to 1,200 times more poisonous than cyanide. So poisonous that one puffer fish can kill 30 adult humans. So poisonous that puffers are reportedly the second most poisonous vertebrate in the world, which is why it's also surprising that us humans? We actually eat them. That's right. In Japan, puffer fish is actually a delicacy called fugu, which only trained chefs can prepare.

And considering that these fish are basically spike balls filled with poison and we're still serving them in restaurants, they must be seriously delicious.

Narrator: If you're hiking pretty much anywhere in the US, this is one sound you don't want to hear...[Audio of rattlesnake rattle.]

The warning of a rattlesnake.

Now, just because a rattlesnake's tail sounds like a built-in maraca doesn't mean it works like one. There are no beads rattling about in here. So what's really going on inside?

If you opened up a rattlesnake's rattle and shook it, absolutely nothing would fall out. After all...

Colston: Rattlesnake rattles are hollow.

Narrator: That's herpetologist Tim Colston. He says the secret to that rattling sound comes from the shell itself. It's made of keratin, the same hard substance as your fingernails.

The keratin is arranged in a chain of interlocking rings , which are hooked together by tiny grooves along their edge. Now, watch what happens to those rings when Colston shakes the rattle.

Colston: Whenever I shake them really fast, they bump together, producing a sound.

Narrator: Because the rattle is hollow inside, sound waves can bounce off the walls and echo the same way shouting in a cave amplifies the sound. And the bigger the "cave," or hollow rings in this case, the more amplification, so the louder the rattle.

But a big, hollow chamber can't get the job done on its own. That's where the tail muscles come in. Rattlesnakes are equipped with three powerful shaker muscles at the base of their spine. These can contract so fast, they vibrate the rattle up to 90 times a second.

For comparison, the human eye blinks 15 to 20 times a minute. By vibrating so quickly, the rattle makes a sound that hits a specific frequency: 489 to 24,380 hertz. And it just so happens that range is best heard by mammals. It turns out that tail is custom-designed to make predators like bears, raccoons, and weasels listen up.

Unfortunately, snakelets yes, that's what baby snakes are called don't have this warning signal.

Colston: When a rattlesnake is born, it just has a single button that looks similar to this one[points to rattle], if you can see this part on the end here.

Narrator: Without a second button to clack against, the baby rattle can't make any noise! But every time they shed their skin, they add another button to the base of the rattle, which grows into the segment above. Sort of like the structure of a Russian stacking doll.

The rattle will keep growing until ... SNAP. Just like your fingernails, those rattles are pretty fragile and can break off if they get too long. In fact, the rattles rarely make it past eight to 10 rings before snapping off. Luckily, snakes shed their entire lives. So the rattle will grow back, good as new.

Which is good news for you hikers. Because that handy tail can mean the difference between an exciting day on the trail and a painful trip to the hospital.

Narrator: Did you know that camels used to live in the Arctic tundra? Yes, camels! Walking around on ice and snow. It's true. In 2013, scientists announced they'd discovered mummified leg bones on Ellesmere Island, which belonged to the ancestors of modern-day one- and two-humped camels.

In fact, enduring the frigid tundra is how scientists think camels got their iconic hump in the first place, because what's inside helped them survive in an age when many other animals were wiped out.

John Hare: What's inside a camel's hump is fat, and a lot of people think it's water. But it's certainly not; it's fat, and it nourishes them when they're on long journeys.

Narrator: That's right, fat. Each hump can store up to 36 kilograms of it, which can sustain the camel for weeks or even months without food. And that sort of adaptation was especially important 3.5 million years ago, during the middle of an ice age, when the ancestors to modern camels were hanging out in the Arctic tundra.

Hare: Talking about the Ice Age, when a lot of mammals were killed during that time, and yet the camel managed to survive by developing this emergency food system, if you like: the hump.

Narrator: Eventually, camels migrated across the Bering Strait into regions of Asia and Africa, where the fat inside their humps helped them adapt yet again. This time, to the blistering-hot temperatures of deserts like the Gobi and Sahara.

You see, camels are one of the only animals in the world that store all their fat in one spot. And that's useful for keeping cool in a hot climate because heat can escape faster from the rest of their body, which helps them maintain a lower body temperature. Compare that to other mammals, like humans, who store fat all over, making it a lot harder to stay cool.

Today, camels still use the fat in their humps as a food reserve, but they're not the only ones. In extreme circumstances, the Turkana tribe in Kenya, for example, will eat camel fat to survive.

Hare: They suffer a lot from periods of extreme drought, and I have seen these people, they've been very, very short on food, and this is difficult to believe, but it's true, slit open the top of a camel's hump, take out the fat for their own consumption, and then put the top of the hump back on again.

Narrator: But don't worry, the camel makes a full recovery, and instances are rare. But this practice has started to generate some buzz around camel fat as a new superfood. Turns out, camel fat is loaded with fatty acids, vitamins, and minerals. Desert Farms, a company that sells camel fat, says that just 1 tablespoon contains 40% of your daily vitamin B12 needs and three times the amount of oleic acid than coconut oil, a superfood staple. And since all that nutritious fat is what fills the hump out, when a camel fasts for long periods, its hump can actually go limp.

Hare: The humps gradually diminish in size. If it's been in a very harsh environment, they go completely limp and flop over the side of the camel's backbone.

Narrator: Now, since we know that fat is what makes up the hump instead of water, that got us wondering: How do camels stay hydrated in such dry climates? Well, they have unique blood cells that run throughout their entire body, including a few in the hump itself. These blood cells are extremely elastic, perfect for holding a lot of water. Camels can drink up to 115 liters in about 10 minutes, expanding the cells up to 240% in the process.

Hare: There are capillaries throughout its body, and when it has a drink, it drinks and drinks and drinks, and it swells up, and it looks as though it's pregnant.

Narrator: If that's not impressive enough, the wild camel of China has even been known to survive on salt water.

So, whether it's surviving the harsh desert heat, weeks without food and water, or even the Canadian Arctic, the camel is one of the best adapters in the animal kingdom, and that's in large part thanks to its iconic hump.

Narrator: At first glance, a fire ant hill or mound, as it's properly called looksimpossiblysmall. And yet, a colony of up to 250,000 ants call it home.

But here's the secret:That mound is just the tip of anenormousiceberg.So let's take a closer look at what's inside an anthill.

The mound is really the top of an enormous underground structure: the nest.Which is basically a giant nursery: a nice, cozy place to raise babies.

A lot of babies.Their mother, the queen, roams around the nest while laying 1,500 eggs a day!

Now, all those baby ants need to live in a narrow temperature range to grow, so that nest sports temperature-controlled rooms.And it does so without the help of an AC unit.

The secret's in the design.The nest is arranged like an ice cream cone.At the top, you have the mound the ice cream, as it were.Because it's above the surface, it warms up from the heat of the sun. So the babies can snuggle up in toasty chambers networked throughout the mound.

But they can't stay there all day, or they'd get TOO hot.That's where the cone part of the ice cream cone comes in. The mound is connected to several vertical shafts that plunge up to 2 meters beneath the ground,taller than most adult humans!

Throughout the day, adult ants ferry the babies up and down the shafts, chasing the perfect temperature for their young charges.

The nest also sports dozens of tapering tunnels that branch off from these main shafts.These connect to small chambers where the ants rest, eat, and feed the babies until it's time to move the little ones again.

Now, there's one more type of tunnel inside the nest, but only a few ants ever use it. You see, someone needs to find food for the rest of the colony.But running around outside the nest is dangerous business.

That's where forager tunnels come in.These are a couple of horizontal passages buried just a few centimeters from the surface.They run throughout the entire territory, which can cover up to 185 square meters of land!

By scurrying through these passageways, the scouts can stay underground as long as possible.But, unfortunately, the nest and all its roads can't protect the ants fromevery threat.It turns out, all sorts of critters sneakinsidefire ant nests.

And while many of them are harmless, others are horrible house guests.For example, beetles burrow into the nest and devour the eggs and larvae!

But invaders aren't the only threat to the colony.Occasionally, clueless humans or major floods disturb the nest.And when that happens, the fire ants have only one option: leave.

Once a year, on average, the colony will move out and build an entirely new nest from scratch. And best of all, they only need a few days to do it.

That's right. Practically overnight, meters upon meters of tunnels can pop up in your yard.

And all you'll notice is a tiny mound.

Narrator: A turtle's shell is as much a part of its body as our rib cage is of ours. In fact, it is their rib cage, and their spine, and their vertebrae, and their sternum. Basically, a turtle's skeleton is inside out. And just like you can't take a skeleton out of a person, right, you can't take a turtle out of its shell either. But if you could, you'd probably be surprised by what you'd discover.

Maria Wojakowski: Here's the inside of a turtle.

Narrator: That's Maria Wojakowski, a biologist who's been studying turtle ecology for more than a decade.

Wojakowski: Here's your shoulder girdle. Here's your hip girdle.

Narrator: Notice how those hips and shoulders are actually inside the turtle's rib cage? Turtles are one of the only land animals on the planet with this feature. They're also some of the only animals that can breathe with their butts. You see, inside a turtle shell is a very particular respiratory system.

Wojakowski: You will see the lungs towards the top here.

Narrator: Now, most land animals breathe by expanding and contracting their ribs, which creates a natural pump that guides air in and out of their lungs. But turtles can't do this because their rigid shells don't expand. So instead they rely on sheets of muscles within their shell to pump in oxygen through their mouths.

That is, most of the time. Then there are other times when turtles breathe out the other end, more specifically, through what scientists call the cloaca. It's the same opening that turtles use to urinate, defecate, and lay eggs. And in some cases, it can double as a set of gills, sucking in water and absorbing the oxygen within. Scientists think that turtles do this when they're spending long periods of time underwater, like when they're hibernating.

And if you look really closely at the inside of a shell, you'd discover another feature that helps with hibernating underwater: a scaffold-like structure that can store and release chemicals. That structure actually helps turtles breathe without any oxygen at all.

It works like this: Many turtles hibernate in frozen ponds that are starved of oxygen, and to survive, their metabolism switches over from aerobic to anaerobic. That means they stop using oxygen for energy and start using glucose instead via a process called anaerobic respiration. And the byproduct of that is lactic acid. Now, theoretically, this acid could build up in a turtle's body and kill it.

That's where the shell's structure comes in. It can absorb the lactic acid as well as release a bicarbonate to neutralize that acid. It's essentially Tums, but for turtles. So as it turns out, having a shell is pretty handy for certain situations. In fact, scientists think that turtles originally got their shells for digging, likely more than 200 million years ago.

Wojakowski: They dig, like, really, really complex burrowing structures underground.

Narrator: And of course, shells are incredibly useful for defense against predators, no matter how fierce they may be. Turtles are amazing.

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