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00:08Survival in the Animal Kingdom is a high-stakes game of strategy and strength,
00:14where defensive capabilities are essential.
00:18Nature has bestowed some species with the gear of a defensive warrior.
00:23Evolution has equipped them with some incredible tools
00:26to both defend themselves from the environment and from other animals.
00:30In the dangerous dance between predator and prey,
00:34bearing these adaptations can mean the difference between life and death.
00:38The predator lunges and gets a face full of quills.
00:41Imagine facing a bird that could deliver a roundhouse kick with its full body weight.
00:47From impenetrable shells to razor-sharp scales,
00:51these adept survivors are some of planet Earth's best at defending themselves.
00:56I would run away if it was running at me.
00:58How have these creatures adapted to thrive in a world of danger?
01:03And what can we, in our own fragile existence,
01:07learn from their incredible adaptations?
01:31In nature's arena, where predator and prey are at constant odds,
01:35one unlikely warrior has mastered the ultimate art of defense.
01:42Beneath a deceptively harmless demeanor, the porcupine is a walking fortress
01:47that can cripple enemies several times its size.
01:52Its name comes from the Latin terms porcus and spina, meaning spiny pig.
01:59But this creature is actually one of the largest rodents on Earth.
02:03Like all rodents, the teeth grow continuously, so they need to keep gnawing,
02:08they need to keep chewing to kind of grind those teeth down.
02:10The physiology of their teeth is very similar to a beaver.
02:13Rodents have ever-growing teeth, but the incisors, which are the two front top and two front bottom,
02:19rub up against each other so much that they become razor-sharp, and they can bite through anything.
02:25But it's not the sharp incisors that make this creature one of nature's best in combat.
02:31It's the payload of deadly spears bristling from its skin.
02:37Porcupines are notorious for their unique coat of quills that can be easily ejected into an unsuspecting victim.
02:43Not only do they protect the animals, they can also act as a weapon in their own right.
02:49So why have they evolved such a dangerous arsenal?
02:53And what are the consequences of a porcupine's pierce?
02:57All species fall within two distinct groups.
03:01Old-world porcupines can be found in Asia, Africa, and Europe.
03:05New-world porcupines are found in the Americas.
03:08Like old-world porcupines, they're mostly herbivorous and nocturnal,
03:12but they also spend a fair amount of time climbing trees in search of food.
03:17There are over two dozen species across every continent except Antarctica,
03:22where they seek out territory rich in vegetation.
03:26Yet, it's in these very sanctuaries where danger also tends to thrive.
03:32Porcupines have evolved a number of characteristics to survive in their respective territories.
03:38Because this animal lives in so many diverse environments,
03:42it comes up against a range of fierce predators, from lions to wolverines to coyotes.
03:48The way to get at a porcupine, if you're a predator, is to go under.
03:53Porcupines are covered in quills everywhere except their face and their belly.
03:57So if you can flip one over, they're a little bit defenseless.
04:00And yet, very few animals will risk such an attack because one false move could prove detrimental.
04:10Hidden amongst the fur of all porcupine species is a biological superweapon,
04:16the sharp extractable quill.
04:20Porcupine quills are very sharp, so once an animal goes to bite the porcupine,
04:26the quills stick into their face, into their muzzle, and become embedded there.
04:30And this dissuades the animal from further attacking the porcupine.
04:35It's a really amazing defence mechanism because it's extremely effective.
04:39So, what is a quill exactly?
04:42And how does this thin structure ward off such a wide range of predators?
04:47From the moment they're born, porcupettes, or baby porcupines,
04:52are adorned with a protective layer of soft quills,
04:55that begin to harden within a few days.
04:58Porcupine quills are actually hollow hairs,
05:02held in place by special hair follicles and connected to adductor muscles.
05:06So porcupines have some ability to control how these kind of rays and appear on the body.
05:11Normally, porcupine quills will be pretty flat when a porcupine is threatened.
05:15In the same way that a human being might get goosebumps and feel their hair raise up on their arms,
05:20a porcupine can raise up these quills to make itself appear more threatening and more dangerous.
05:26For some species, these erect spines can measure upwards of 50 centimetres in length.
05:33But before it puts these deadly spears to use,
05:36the porcupine employs clever evasion techniques
05:39that all begin with its inconspicuous coat.
05:43While porcupine species vary in appearance,
05:46they often sport darker coats that are a little harder to see at night when they're most active.
05:50Especially for arboreal porcupines in North America,
05:53their kind of shaggy, lumpy bodies often resemble things like squirrel nests and bird nests.
05:59And this also gives them a little bit of camouflage when they're up in those trees
06:02to help avoid predators.
06:05Many species of porcupine rely on their ability to climb trees aided by strong claws and vestigial
06:12thumbs to avoid ground-dwelling dangers.
06:23But sometimes a swift ascent is not an option.
06:29This spiky rodent is also ready for combat at ground level.
06:33The quill is the porcupine's pièce de résistance.
06:38But the creature also comes equipped with postures and sounds that are meant to frighten other creatures away.
06:46When a porcupine's threatened, it'll typically engage in some aposematic defense tactics.
06:52The goal of this is to try to appear as threatening as possible,
06:56make it seem like the least attractive type of snack to eat.
07:00With its quills on full display, the animal then draws from a repertoire of strategies to frighten its opponent.
07:08What they will do is whip their tails to both try to ward off predators and also give themselves a
07:14little space.
07:15The animal then turns its backside to the enemy, showing off an area known as the rosette,
07:20which is the most densely packed with spears.
07:23Yet, what if a brave foe fails to be stopped by this visual display?
07:29Locked in the porcupine's rosette is a unique set of quills known as osmotrichia,
07:35under which the porcupine's sebaceous glands release a potent,
07:39almost suffocating odor that few predators can ignore.
07:43When these quills are bristled in the presence of danger,
07:46their upright posture helps spread smelly odorants throughout the air.
07:51Similar to the tactic of a skunk, this smell is meant to turn off predators
07:55and convince them that they're not a tasty meal.
07:58The odor of porcupines isn't really like a skunk, it's more of a deep funky smell,
08:04like a really old stinky cheese.
08:07What the porcupine's trying to do with this stink is deter predators from approaching it.
08:12This smelly tactic used by animals like porcupines and skunks is so potent,
08:18in fact, that it has inspired human-made deterrence.
08:22To this effect, police forces are starting to use similar compounds,
08:26starting to adapt this type of odorant to disperse crowds and displace people.
08:32If these fearsome postures and olfactory cues fail to scare the enemy,
08:38the porcupine will have no choice but to deploy its mightiest weapon of all.
08:44Some species carry an arsenal of over 30,000 sharpened quills,
08:49and in a single attack, can eject several hundred at a time.
08:54But this daring move requires a close encounter.
08:58A lot of people think that porcupines can shoot out their quills,
09:00but that's not actually true, that's a myth.
09:02We know the porcupine doesn't shoot its quills like bullets or like throwing knives,
09:08but they will detach upon contact.
09:10Imagine it like a spring.
09:12When a quill is touched, it slightly retracts into the follicle,
09:16tearing a spool of connective tissue and releasing it from the porcupine.
09:20In a single attack, the porcupine can eject several hundred spears,
09:25and for some, each one is tipped with lethal power.
09:30Species like the North American porcupine have quills containing nearly 800 barbs in just a few
09:35millimeters nearest to their tip, ensuring that what easily pierces stays in with unforgiving grip.
09:43For animals lacking thumbs or strong jaws, quills can be incredibly difficult to remove.
09:49These barbs on the quills are a lot like a fishing hook.
09:51The barbs at the end of the quills grip the flesh like anchors.
09:55The quills can work their way into a victim at the rate of one millimeter per hour.
10:00This means that if they're left untreated, a quill could eventually puncture a vital organ.
10:07So how exactly does this creature protect itself from the dangerous payload on its own back?
10:12Or from the spikes of other territorial porcupines?
10:17Porcupine quills are coated in fatty acids that essentially act as a natural antibiotic.
10:23These fatty acids feel almost greasy to the touch, and they inhibit the growth of several forms of bacteria.
10:29Which is not at all what you would expect from, you know, a really fearsome animal covered in needles.
10:35But they're covered in this antibiotic property.
10:37Of course, these porcupines are carrying around this jacket of needles 24-7.
10:41And every now and then they fall off a tree.
10:43Every now and then they'll hit themselves or hit a mate or something.
10:46So if the porcupines get injured by a quill, then they're very unlikely to get an infection.
10:51Scientists are looking to the compounds on porcupine quills to actually improve healing properties.
10:58Porcupine quills also have very interesting barbs in that they're very tiny.
11:03And this property can allow two pieces of tissue to stay bonded together.
11:09So scientists and engineers are looking at the structures on porcupine quills to replace sutures.
11:16In comparison to modern surgical staples that curve under the flesh to stay put,
11:22new quill-inspired designs could be inserted straight, allowing for a less invasive insertion.
11:28It's a wondrous example of the potential of biological engineering to both deter and protect.
11:35The porcupines have a great defense with their quills, and if a predator would try to bite them,
11:40they would hopefully run away and then the porcupine can escape.
11:44The porcupines are a little bit like reluctant warriors.
11:47They're covered in these spines, but they really try not to use them.
11:53Many defensive warriors are reluctant to deploy their weapons, preferring to threaten rather than fight.
12:01But others have evolved to be quick to defend themselves with a lethal kick.
12:07One such species is not just a visual echo of the dinosaurs, but a direct descendant
12:13of Earth's prehistoric giants. Deep in the tropical forests of Oceana is a magnificent feathered creature
12:21known as the cassowary. Cassowaries are actually very beautiful. They have a blue face. Their eggs
12:27are bright green, which is shocking. They look like a bright green avocado.
12:32But behind this rare beauty is a bird that's supremely equipped for battle.
12:37These birds are actually pretty dangerous to be near.
12:41It has famously earned the title of the world's most dangerous bird. But why?
12:48Well, compared to its avian cousins, the cassowary boasts a number of threatening adaptations
12:54that would make any potential predator think twice. I wouldn't be near a cassowary, but they're
13:02very interesting to look at. They have very large feet and claws, and it looks like a raptor. It's tall.
13:09In fact, the southern cassowary stands out as the second heaviest and third tallest bird in the world.
13:16A creature that, as one of the oldest avian species today, traces back around 60 million years.
13:23Cassowaries are like living dinosaurs. They're believed to be the closest living descendants
13:27to a group called theropods. Theropods were carnivorous dinosaurs from which all bird species evolved.
13:33It bears a striking resemblance to its ancient ancestors, including its three sharp toes.
13:39Bearing muscular legs and dagger-like talons reminiscent of its giant ancestors,
13:45the brightly colored bird likely evolved on the ancient supercontinent of Gondwana.
13:50And as the land fragmented over time, it diverged into the three distinct species we see today.
13:57Today, there are three known species of cassowary. The northern, the southern, and the dwarf.
14:03All of these birds roam the forests of Australia, New Guinea, and other islands throughout Indonesia and
14:10the Pacific, where they must contend with a perilous ecosystem full of enemies, like crocodiles, snakes,
14:17and wild dogs. For this creature, biological weaponry is especially essential,
14:23because it belongs to a grouping of birds that are bound to the land.
14:27A cassowary is a bird that is known as a ratite. It has a flat breastbone without a keel. The
14:33keel is
14:33a ridge in the breastbone that is typically used for flight. Therefore, ratite birds can't fly.
14:39Without the ability to fly, how does such a large, flashy bird evade encounters with land-dwelling
14:45carnivores? It begins with the unmatched power of their formidable legs.
14:52The bird is very skilled in both swimming and jumping. It can actually launch itself
14:57in the air up to two meters, often higher than its own height, which allows it to stomp out potential
15:03threats. Cassowaries have rear-facing knees. Basically, instead of their legs bending towards
15:09the front, they bend towards the back. This design gives the cassowary a very stable
15:15center of gravity. When you have knees like a human, it's very difficult to maintain stability.
15:24This hinge mechanism that faces backwards is much more stable, because when the foot comes down,
15:31it essentially remains under the center of gravity. Generally speaking, knees which face backward,
15:38it's a preferred design for more stable robots.
15:43The leg power of the cassowary has inspired an American bipedal robot, aptly known as Cassie,
15:50which takes full advantage of these backward-facing knees. The powerful legs and joints of the cassowary
15:58enable devastating kicks in both forward and downward direction, deterring adversaries from multiple angles.
16:06These sturdy limbs make up for what appear to be a glaring weakness. Wings that span barely 30 centimeters,
16:14nowhere near large enough to carry the bird's weight. So if they cannot be used in flight,
16:21why evolve wings at all? The true advantage is what lies beneath.
16:26Beneath its wings are long quills made of keratin that extend around its body and its upper legs. The bird
16:33is
16:33covered in coarse, double-shafted feathers, quite shaggy in appearance. Collectively, these features act like
16:41a shield as it zips through the thick undergrowth at incredible speeds. The southern cassowary has robust,
16:48muscular legs that allow it to run really fast, up to 50 kilometers per hour. To put this in perspective,
16:55the human speed record is 44.72 kilometers per hour. Imagine facing a bird that could charge at you at
17:0250
17:02kilometers per hour, jump two meters in the air, and deliver a roundhouse kick with its full body weight.
17:09This is definitely an animal you want to be cautious around. Though armed with the speed of a supreme hunter,
17:17the cassowary is an opportunistic eater, preferring whatever is easiest to find. The majority of its diet,
17:24about 90 percent, comes from fruit. This fruit-based meal plan is incredibly beneficial to the bird's
17:30ecosystem. Because it eats fruit whole and has a relatively short digestive tract, it actually excretes a
17:37lot of seeds still intact. In fact, some species of seeds rely upon passing through the bird's digestive
17:44system to sprout. This flightless gourmand's favorite snack is large seeded fruit, of which it can eat
17:52around five kilograms per day. Yet lacking hands, teeth, or even a tongue, how does it forage and feast?
18:01The large talons on its innermost toes serve as the bird's most effective culinary
18:06tools. These hooked nails can grow up to 12 centimeters long, allowing this omnivore to dig
18:13through soil, pierce fallen fruit, and eviscerate potential prey, like insects, fish, and small rodents
18:21and reptiles. Most birds of prey have very strong serrated beaks that they use to cut up their prey.
18:29Cassowaries don't have that strong serrated beak, so they really rely on these sharp claws to cut their food up.
18:37The bird's personal butcher knife is also a useful tool for battle. The cassowary is fiercely
18:44territorial, known to aggressively guard its feeding grounds. Should any neighboring bird or hungry
18:50opportunist attempt to steal a bite, these mighty appendages will be put to detrimental use.
18:56The talons of the cassowary are sharp enough to slice through the skin and flesh of medium-sized mammals.
19:03When backed by the kick of their powerful legs, this bird could easily break bones and even rupture organs.
19:13Fortunately, this claw-bearing cassowary prefers a life of solitude, only crossing territory with other
19:21birds to mate and rear their young. It takes nine months for a cassowary chick to grow and become
19:28independent of their parents. As the young cassowary leaves the nest to become its own bodyguard,
19:33a striking feature atop its skull begins to take shape. All species of cassowaries grow what's called
19:40a cask on the top of their head. This is a tough tricorn shaped enlargement that grows on the upper
19:47mandible. It's made of a bony core composed of keratin. At first glance, it appears this helmet-like
19:55cask could be a crucial component of the cassowary's defensive arsenal. The cask looks like the bird's
20:02very own gladiator gear, like a helmet attached to their body. However, while the cask appears quite
20:07formidable, the bone is not entirely solid. The hardened shell is only two to three millimeters thick,
20:13and within that is a porous honeycomb-like structure that's actually quite soft. Though this seemingly
20:19sturdy headpiece may not be ideal for direct combat, it could help the cassowary ward off threats by
20:26heightening its acoustic abilities, like a giant megaphone. The cassowary communicates through a range of
20:34sounds, from hisses and grunts to powerful calls called booms that are meant to ward off threats or to
20:42attract other birds. Remarkably, these birds produce the deepest sounds of any avian species, reaching
20:48sound frequencies as low as 24 hertz. Their calls approach the threshold of infrasound, which is
20:56actually below the level that humans can detect. Some theories suggest that the cavernous pockets
21:01inside the bird's cask actually acts like a sound amplifier, helping amplify the sound throughout the
21:08forest to other birds. This porous crest is connected to the ear cavity, leading some researchers to
21:16believe it may also enhance the bird's ability to detect the deep calls of others. An unmistakable
21:22rumble that may warn of a looming conflict. Some researchers have reported that the birds' calls are
21:30so powerful that they can actually feel it in their bones. This booming rumble makes the cassowary's
21:37connection to the dinosaurs all the more believable. From head to toe, the cassowary stands as one of
21:44the fiercest-looking birds in the animal kingdom. Accordingly, it has no natural predators aside from
21:51humans, who in parts of Indonesia and Papua New Guinea hunt the creature for its feathers and meat. On the
21:58rare occasion, they can find the elusive bird. The cassowary is often dubbed the world's most dangerous bird,
22:04but this reputation comes solely from its capabilities and not from its actions. According to available
22:11statistics, only two human deaths have been recorded that can be attributed to cassowaries. When we compare
22:17this to other large birds like ostriches, which typically kill two to three humans per year, this
22:24reputation really isn't warranted. In fact, recent research suggests that the cassowary may have been the first
22:31bird domesticated by humans around 18,000 years ago in New Guinea, several millennia before we raised the
22:39common chicken. It's hard to believe that these fearsome birds could have been the chickens of ancient
22:45tribes. Even in a domesticated setting, cassowaries have the ability to inflict serious harm. This is
22:52probably why we don't see very many domesticated cassowaries today. They're probably best left alone in the wild.
23:02Beneath the cover of a sturdy shell with a powerful beak and long menacing claws,
23:07lurks another of nature's warriors, thought to be the most dangerous snapper to exist.
23:14This is the alligator snapping turtle, a creature often regarded as the dinosaur of the turtle world.
23:22The alligator snapping turtle gets its name from its strong jaws and its textured shell, strikingly
23:27resembling the tough hide of an alligator. The alligator snapping turtle has been roaming the earth for
23:34between three and nine million years. Today, it's endemic to the freshwater rivers and streams of the
23:42southeastern United States that feed the Gulf of Mexico. When you're seeing an alligator snapping turtle swim
23:48out of the murky water, it looks like you're seeing an animal come out of a whole different time.
23:54This lumbering heavyweight is the largest freshwater turtle in North America.
24:00In the wild, male alligator snapping turtles tend to grow between 70 and 90 kilograms.
24:05Females are generally smaller, only reaching around 30 kilograms.
24:08One of the biggest specimens ever recorded weighed in at 135 kilograms. That's about the size of a newborn baby
24:17elephant.
24:20However, size alone may not be enough to fight off all hungry predators.
24:26Luckily, evolution has armed this reptile with a lightning-fast snap of incredibly powerful jaws.
24:33Their jaws are kind of like a bear trap. And just like a bear trap, when they shut, they're not
24:38going to let go.
24:41Though toothless, the turtle's mouth is aided by a pointed beak and jaw muscles that can deliver
24:47a bite force of 160 newtons, enough to tear through flesh and bone and dissuade most of the animal kingdom
24:55from trying their luck. Humans are thought to be the only known true predators of these snapping turtles.
25:02And if a human gets too close, their jaw is powerful enough to amputate a finger.
25:08These jaws are a crucial insurance policy for an animal with a top land speed of just four kilometers
25:14per hour. But before they put their bite to devastating use, this snapper relies on a sophisticated suit
25:22to shield it from attack. These are large, slow-moving animals, but what they lack in agility,
25:28they make up in armor. This near-full body covering can measure up to one meter in length.
25:36Unlike animals like hermit crabs, when they grow, they have to leave their shell to find a new,
25:41larger shell. The turtle shell actually grows with the turtle. And the shell is actually an extension
25:48of its rib cage. If you imagine a cartoon, a turtle leaving its shell, it's not possible.
25:56This shell is part of the turtle's skeleton, containing nerve endings and over 50 ossified bones
26:03that are fused to dermal plates below the skin. As the creature grows, so too does its shield.
26:10So how exactly does this biological armor work? The secret is its scoots, overlapping plates that
26:18form a hardened exterior, which shields the bony shell from scrapes and punctures. Hundreds of species
26:25of turtles and tortoises grow these tough scoots atop their shell. However, the alligator snapper boasts
26:32an especially frightening design. Unlike smooth-shelled turtles, the alligator snapping turtle has three rows
26:39of spikes called keels, and they're arranged from head to tail along the turtle shell.
26:45These enlarged spikes are made from keratin, a structural protein produced by all vertebrate species
26:53in the animal kingdom. Keratin, which is what horns and hair and fingernails are made of, is a very
27:01versatile, naturally occurring polymer. Polymer is essentially the base material, the plastic, very much
27:09like we would use in engineering and science. Keratin's really an amazing material because it's tough and strong.
27:19And yet, despite that strength and flexibility, cracks and fissures can leave all turtles vulnerable
27:25to deadly infections and opportunistic predators. Luckily, however, this turtle shell has an astonishing
27:33ability to self-repair. When you look at a turtle shell under the microscope, it has a texture. So it's
27:41kind
27:42of like the entire shell of the turtle is made of microscopic chain links to give it flexibility. It's very
27:49difficult for a predator to puncture that carapace because instead of breaking and cracking, it will tend
27:56to flex first. Despite this sophisticated shell and bone-crushing bite, the turtle's slow speeds and
28:04top-heavy build still leaves it vulnerable to attack. So this ancient predator prefers a life on the murky
28:12riverbed where its rugged carapace becomes virtually invisible. You can get algae or other vegetation growing
28:20on their shells, which is perfect camouflage, and if they could sit and wait for prey to come near them,
28:26it's even better. Alligator snapping turtles spend the vast majority of their lives in the water. They eat
28:32there, they mate there, and they even sleep there. They stay underwater for upwards of 50 minutes at a time.
28:39Even when they do surface, their noses act like little snorkels so they don't have to come fully out of
28:44the
28:44water to breathe. But this aquatic refuge cannot provide for all of the alligator snapping turtle's
28:51needs. Each year, driven by instinct and necessity, the turtle must emerge from its watery haven to ensure
28:59the continuation of its lineage. The only time they'll really leave the water is to change habitat or during
29:06nesting period. Though mating occurs in the water, eggs must be laid on land, a domain where
29:14carnivores may lurk just beyond shore. The female first locates a suitable site of sandy soil,
29:22usually within 50 meters of the shore, before excavating a nest with her claws. Time is of the
29:29essence. The longer she remains on dry ground, the greater the chances of encountering trouble. Soon,
29:36she deposits her precious cargo and makes a swift return to the river. Turtles lay their eggs and they
29:43leave. From this clutch, not all make it through the incubation period. The eggs take between 100
29:51and 140 days to incubate. During this time, they're incredibly vulnerable to predators. For many species
29:59of turtle, hatching is just the beginning of their struggle for survival. Some of their main predators
30:05are carnivorous mammals, birds of prey, and even lots of fish. All of these animals will prey on the
30:11hatchlings. It's not until they reach full maturity that they're able to make use of those spikes on
30:16the backs of their shell. Once they make it to the water, however, the alligator snapping turtle will
30:22grow to dominate the current as an apex predator. Most turtles are scavengers. They're going and looking
30:31for dead fish carcasses, anything that's fallen to the bottom of the lake or river to scavenge.
30:38Alligator snapping turtles are a little different. In fact, they're hunters. Yet, rather than spending
30:44energy giving chase, it's an assassin that prefers to lie in wait for its victims. It opens its jaws,
30:52revealing a mouth coated in camouflage and a special tool on its tongue to secure the hunt.
30:58They have a really unique adaptation in that their tongue is variform. It kind of looks like a worm,
31:06and then fish or other aquatic species come to try and grab that worm-like structure.
31:13It almost looks like a human's fishing lure that we use to catch fish with,
31:17and that's exactly what they're doing.
31:22In mere fractions of a second, what was once a living creature becomes nothing more than a snag,
31:29sealed by a single devastating bite. These bone-crushing jaws, combined with its incredibly
31:37resilient exterior, grant this docile creature the status of one of nature's most powerful warriors.
31:50A well-built shield is a valuable asset for warriors big and small. No creature knows this better than
31:57an animal adorned with a unique coat of sharp, overlapping scales that form a near-unbreakable
32:03dermal armor. At first glance, this rather unusual-looking creature may be mistaken as a reptile. However,
32:11the pangolin is, in fact, a member of the mammalian family.
32:15Pangolins are the only mammals that are completely covered in scales. They look like a walking artichoke.
32:21They resemble anteaters as well, but they're actually more closely related to bears and cats.
32:28There are eight species of this creature, which are native to regions of sub-Saharan Africa and Asia.
32:34Here, apex hunters like leopards, lions and hyenas roam the terrain, all hungry and eager to snag a bite.
32:44Like some carnivores, the pangolin wields long claws and a powerful tail. But it's the impenetrable
32:51barrier of scales covering its body that equip it best for battle.
32:55Pangolins, for defense, they curl up into a tight ball and the scales act as very hard armor.
33:03Derived from the Malay word pungoling, meaning one who rolls up, the pangolin's defensive tactic is used
33:10when all else fails. Pangolins have an incredible defense tactic that we call
33:15volvation. This is basically them rolling up into the tightest ball they can.
33:20When this relatively small creature encounters danger, it takes mere seconds to react,
33:26pulling all of its limbs, including its head, into the protective embrace of its dermal shield.
33:33Even predators willing to breach the tough exterior of other prey, such as the shell of turtles,
33:39will be reluctant to contend with the hundreds of razor-like plates between its jaws and the pangolin's
33:45flesh. The best offense really is a good defense. But before it resorts to this rigorous role,
33:54it often digs a hideout below the cover of the earth. Pangolins are exceptional diggers. Some ground
34:01dwelling species of pangolin will dig tunnels to a depth of 3.5 meters. Within these burrows,
34:08they'll create spacious chambers for nesting, for sleeping, and escaping the heat on a hot day.
34:14Some discovered chambers have been so large that an adult human could crawl inside and be pretty
34:21comfortable. In some Chinese legends, these creatures are said to journey across the entire
34:26planet beneath the ground. So how does such a small creature create such vast underground chambers?
34:35Assisting in this subterranean endeavor are the rough-edged plates across its body.
34:41This specialized armor transforms the pangolin into both a fortified tank and a tunnel boring machine.
34:48Animals that dig need protection from the soil that they're digging through.
34:52The scales on the pangolin are corrugated and they have anti-adherence properties, which means the soil doesn't
35:00stick to them. And the tough, hard scales also protect them against abrasion from the soil.
35:06The overlapping plates account for around 20 percent of the pangolin's mass.
35:12Yet it takes time for this defense to form. In their first moments on earth, baby pangolins are adorned
35:20with soft, delicate scales that offer little protection.
35:24Pangolins give birth to one to three pups and they're called pango pups. When pangolins are born,
35:30their scales are actually very soft. They require their mother's protection for about two years.
35:36Many young pups prefer to stay shielded behind their mum, often hitching a ride on her incredibly long
35:42tail, which can measure up to 70 centimeters, sometimes twice the length of the rest of their bodies.
35:48The aptly named long-tailed pangolin boasts an astounding 46 to 47 vertebrae in its tail alone.
35:57For some species, this tail is prehensile, meaning it can act as an extra limb as they travel through the
36:03canopy.
36:04Above all, the tail is the pangolin's lifeline, an anchor that provides protection, stability,
36:11and grip as the animal evades danger and pursues its next meal.
36:17Pangolins are insectivores. They stick their tongues down into termite mounds. They need some
36:22method to actually capture the insects. The pangolin's tongue is covered in a very thick,
36:28sticky saliva that acts very much like flypaper. Living alone, these mammals can afford to be fussy,
36:36and despite their limited diet, they often perform an integral service to their ecosystem.
36:42These animals can eat up to 20,000 insects per day, with some species consuming more than 10% of
36:49their
36:49body weight in a single meal.
36:53This makes pangolins kind of a natural pest control. They can eat up to 70 million insects per year,
36:59and protect an area of up to 31 football fields from the impacts of termites.
37:05To locate these delectable critters, the pangolin relies on its keen senses of smell and sound,
37:12often standing on its hind legs to catch a promising sensory clue.
37:17This hard-of-sight mammal then tears into mounds and bark, before unfurling an absurdly long tongue to
37:25sop up its supper.
37:26Pangolins have an exceptionally long tongue. It can reach half of their body length when it's fully
37:31extended. Rather than being anchored to the bones of the neck, like most mammals, the root of the
37:37pangolin's tongue is attached to the end of its sternum, between its last rib and its pelvis. The
37:43pangolin's tongue is not only exceptionally long, but it's also very thin, only about a centimeter in
37:48diameter. This allows the pangolin to probe insect mounds and nests.
37:52But how does this toothless creature digest a meal without the ability to chew? For one,
37:59it ingests small stones known as gastroliths, rocks that reside in the gizzard and help grind up its
38:06feast. Remarkably, the gizzard is lined with the same abrasive scales that cover its exterior,
38:13further enhancing its ability to break down prey. And whether inside or outside, these resilient
38:20structures have an astonishing ability to self-repair. When a pangolin's shield does
38:27sustain minor damage on nature's battleground, all it needs is a splash of water.
38:33Pangolin scales, when they're exposed to water, actually swell. So when a pangolin gets a tear or
38:41damage to their scales, when it's exposed to water, the scale itself expands, healing the damage to the
38:49scale. If we can do that with engineering materials, we'll basically have materials that can be damaged,
38:56but self-healing. And this is really important for stuff like military armour. The remarkable properties
39:03of these overlapping scales, both resilient and flexible, are serving as inspiration for advancements
39:09in human technology. Pangolin scales have really interesting structures that make them extremely
39:17lubricious. Basically, things flow very easily past the scale topography. So scientists and engineers
39:24are looking to the structures on pangolin scales to produce scalpels that cut more smoothly through tissue
39:31to produce cuts that heal more easily. Scientists are just beginning to understand the impressive
39:38biological armour that nature bestowed upon this creature millions of years ago. Pangolins have been around
39:46for about 60 million years, which points to their success as a species. But even as humans look to
39:51pangolins for new scientific inspiration, we also continue to pose its greatest threat. Greatest predators
40:00of pangolins are actually humans. Pangolins are actually the most trafficked animal in the world. People
40:05are targeting their scales. They're being used in traditional medicines. And this is decimating their wild
40:12populations. It's estimated that about 11 pangolins are taken from the wild every hour. However,
40:19as awareness of this extraordinary mammal grows, meaningful actions are being taken to protect those
40:25who remain. Observing and studying these incredible animals gives us some invaluable insights into their
40:32evolutionary success. This is a reminder of how much we can learn from nature and this wonderful planet we
40:38call home. Not every warrior is outwardly big and strong, covered in spikes and armour. Some are small,
40:49soft, and adorable. When you enter the rainforest and look for animals, most of them are camouflaged
40:56very well. They're very hard to see. But poison dart frogs are quite the opposite. They're brightly coloured so
41:02they stand out. They're really the jewels of the jungle. And my favourite one is the strawberry
41:10poison dart frog. It looks like a little spider man. But make no mistake, these colourful poison dart frogs
41:17are one of the deadliest creatures on the planet. They're miniature biochemical warriors. Poison dart frogs
41:26secrete super toxic poison from glands on their skin. And a big signal to their predators that they are
41:33poisonous is their very bright colours. You could touch a poison dart frog, but if you were to lick a
41:39poison dart frog, you would get sick and probably die. Some naturalists consider them among the most
41:45poisonous animals on the planet. For example, the golden poison frog is only five centimetres long, but it has
41:53enough toxins on its body to kill over 20,000 mice. Yet why would such a small inviting amphibian require
42:02such a deadly payload? It comes down to the perilous environment in which they call home. Approximately
42:09180 species of these amphibian assassins are found in the humid tropical rainforests of Central and South
42:16America. Here, the ecosystem is abundant in mammals, lizards, snakes and birds that would all consider
42:24frogs a tasty treat. We're not talking about something that's rare in the jungle. These are a very prolific
42:32species. Abandoning the treacherous waters where eels and caimans reside, poisoned dart frogs make a life in
42:40the forest canopy and undergrowth. But survival up here demands an evolutionary sacrifice. Instead of the webbed
42:49feet of their aquatic cousins, these amphibians boast long separate toes tipped with tiny suction cups.
42:56Poison dart frogs, like most tree frogs, are incredible climbers. They essentially spend the vast majority of their time in
43:03trees. Each of the pads on a frog's toes are made up of a large number of hexagonal cells. The
43:09poison dart frog can
43:11move the cells closer together or further apart to grip on the surfaces. The frogs also excrete a mucus,
43:18which further helps adhesion. We find it very interesting as engineers because being able to stick to a
43:25smooth surface and yet remove and reattach that adhesion is something that's very difficult to do.
43:32Scientists and engineers are looking to animals like poison dart frogs to develop technologies that have
43:39temporary adhesion. Yet even amongst the trees, potential predators lurk behind every branch and leaf.
43:48Or at least they would, if not for their secret weapon. But while other frogs depend on speed and
43:57camouflage for protection, poison dart frogs employ an entirely different strategy. One that belongs to
44:04their Dendrobatidae family. Frogs in the Dendrobatidae family host over 500 different types of poisons that
44:12they secrete through their skin. The deadliest is Batracotoxin, which is a fast-acting poison that
44:18affects the nervous system. A lethal dose for a human would only be the size of about two grains of
44:24salt.
44:24Should any predator be bold enough to take a bite? But Trachotoxin ensures it'll be their last,
44:31delivering convulsions, paralysis, and often death. It works kind of like a skeleton key that can force
44:38open the sodium channels on muscle and nerve cell membranes. It's the perfect tool for getting a
44:44predator to drop you or spit you out. Note to self, do not lick random frogs in the rainforest.
44:50The poison is so effective. Some South American indigenous tribes use it on their hunting weapons,
44:57which is where the frogs get their name from. The indigenous peoples of South America capture poison
45:03dart frogs using leaves to prevent them from coming in contact with the poison. They then take their dart
45:09and rub it on the frog. Once it hits the animal, the poison acts very quickly, causing paralysis,
45:15making it exceptionally easy to capture the animal. The poison dart frog's toxins are so feared,
45:22they have only one natural predator. One species of snake, fire-bellied snake,
45:28has adapted a resistance to the Batrachotoxins. They're able to prey on those poison dart frogs.
45:38But if Batrachotoxin is so deadly, what keeps the frogs from accidentally poisoning themselves?
45:45Poison dart frogs have a mutation on the protein receptors on the outside of their cells
45:50that prevents the toxins from interfering with them. Essentially, they have a lock that the skeleton key
45:56can't open. So how do these tiny biochemical warriors get so toxic in the first place?
46:04They don't manufacture poison themselves, but borrow it from what they eat. The toxins come from
46:11their diet. They eat toxic arthropods or bugs, a lot of ants. Poison dart frogs are themselves deadly
46:18hunters. And what's fascinating is that when they're raised in captivity and are fed diets of regular
46:24crickets or other crickets or other non-poisonous invertebrates, they won't produce poisons themselves.
46:28They literally are what they eat. But not all of the threatening cargo they produce is fatal.
46:35In fact, some poison dart frogs secrete compounds that could hold unexpected promise for human medicine,
46:42such as epibatidine. Epibatidine is excreted by Anthony's poison arrow frog,
46:49a species found in Peru and Ecuador. It has potential as a non-addictive painkiller,
46:56an alternative to opiates. It's too toxic in its natural form, but scientists are working on ways
47:01to synthesize a safe version. Few creatures have mastered the art of chemical warfare quite like the
47:07poison dart frog. Deadly toxin is an incredibly powerful weapon, but it only works as a deterrent
47:14if predators know which frogs to avoid eating. This crucial clue is in their color.
47:21Frogs have three layers of color-producing cells. The top layer are xanthophores,
47:27which produce yellow, orange, and red pigmentation. The middle layer are iridiophores,
47:33containing tiny plate-like nanocrystals that scatter different wavelengths of light. Below that are
47:39melanophores, which contain dark melanin pigment. In common frogs, these layers work together,
47:44to create a green color. But in poison dart frogs, variations in the level of pigment will create
47:50whole different shades and variations of color. And melanin distribution can give frogs dark spots
47:56or even stripes. They're not trying to hide. They want to be seen, because those predators have learned
48:01to associate the bright colors to very negative effects. This evolutionary adaptation is called
48:09aposemitism. They've adapted this aposemitism, this I'm very bright colored, I'm toxic, don't eat me
48:18approach. So it's a really great evolutionary advantage. But sometimes the most vibrantly colored
48:24frogs harbor a dark secret. They're not poisonous at all, but merely harmless imposters. This relates to
48:33mimicry, and some species are not poisonous. There's frogs that look like poison dart frogs,
48:40that are non-toxic, that animals won't eat, simply because they're brightly colored and look like the
48:46poison dart frog. The most common aposematic colors are yellow, red, and black. These colors provide an
48:53excellent contrast and visibility. And of course, humans use these same strategies too. Think of red stop signs, or high
49:01visibility vests. All of these are ways to tell people to watch out. What's interesting about these
49:06colors too, is that while they provide a lot of visibility close up, at long range they still tend
49:11to blend into the background. So for poison dart frogs, this provides a lot of visibility and warning
49:16at close ranges, but at longer ranges allows them to camouflage and blend into the environment.
49:22Why poison dart frogs have such an incredible range of colors available to them isn't fully understood.
49:28scientists hope to gain a better understanding by studying their genome. Humans have about three
49:35billion base pairs of DNA. Poison dart frogs typically have about double that. Basically,
49:42poison dart frogs have a lot of switches in their DNA associated with color. It's almost like a lighting
49:48console at a concert, and nature is controlling the intensity and mix of different colored lights.
49:55For the poison dart frog, aposemitism is utilized as more than a battle flare. It also unlocks hidden
50:03advantages in the shadows of the rainforest. Most normal frogs are active at night,
50:10to better avoid predators in the dark. But poison dart frogs need light for their warning colors to be
50:16visible, so they're mostly active in the day. And this actually opens up a whole new niche of food
50:21resources that are also only active in the day. In addition to warding off predators,
50:26having those bright colors also helps in finding mates and in defending territories, where the bright
50:32colors is a signal to how strong or dominant the male is. It shows how amazing evolution can be.
50:40Poison dart frogs are one of nature's most spectacular examples of survival of the flashiest.
50:46Animals have adapted two very different approaches to avoiding creditors when it comes to coloration.
50:53The vast majority of prey try to camouflage themselves and blend in. What animals have come to
51:00evolve instinct-wise is that dull, drab things are okay to eat, and brightly colored things are toxic,
51:07so don't eat them. Small but mighty, poison dart frogs are jewels of the rainforest. And the premier
51:15biochemical warriors on the planet. These defensive warriors, whether covered in toxic poison,
51:23tough armor, or terrible spears, all employ their own systems of survival. Natural engineering,
51:31engineering behind their impressive capabilities, continues to evolve and inspire.
51:36fire.
51:39So
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