- 7 hours ago
Category
📺
TVTranscript
00:08Survival of the fittest isn't merely a contest of strength.
00:12It often comes down to a chess-like game of stealth,
00:16where predators and prey try to outwit each other
00:19by hiding in plain sight,
00:22by moving unseen and unheard.
00:25Humans have used stealth for hunting and war
00:29for millennia.
00:30But it's still nothing compared to the natural world.
00:34Millions of years of evolution have engineered the bodies of some animals
00:38to make them the stealthiest creatures on the planet.
00:41Nature has built these incredible creatures from the cells up to avoid detection,
00:46but other creatures have evolved to find them.
00:49In the evolutionary arms race between the masters of deception
00:53and the masters of detection,
00:55the lives of both predators and prey hang in the balance.
01:00How has nature equipped these creatures for a deadly game of hide-and-seek?
01:05And what might we learn from their clever adaptations?
01:29Consider the chameleon.
01:32These slow-moving, tree-dwelling insectivores
01:35are instantly recognizable for their helmet-shaped heads,
01:39prehensile tails,
01:41independently mobile eyes,
01:44and deadly projectile tongues.
01:49But they're most famous for one evolutionary superpower,
01:53their ability to change color.
01:56Chameleons are one of the first creatures that come to mind
01:58when people think of animals that depend on stealth for survival.
02:01In fact, we use the word chameleon
02:03to refer to people who can change their behavior or appearance to blend in.
02:08It's one of the most unique tricks in the animal kingdom.
02:11So how does this master of disguise
02:13pull off such a breathtaking transformation?
02:17And more importantly,
02:19why is it needed?
02:25Found mainly in tropical rainforests and scrub savannas,
02:29the chameleon habitat extends from the Canary Islands
02:32all the way across southern Europe
02:34and through sub-Saharan Africa.
02:38Nearly half of the 200 species
02:41are found in one place,
02:44Madagascar.
02:45Chameleons vary in size.
02:46Some can be as small as your thumbnail
02:48and others can be as large as a house cat.
02:51Here, the lizard stealthily moves
02:54among the trees and leaves
02:55with the help of a powerful grip.
02:58Chameleons have very highly adapted feet.
03:02They're called zygodactylus feet.
03:04That means the orientation of the toes
03:06are forwards and backwards,
03:08so it looks more like a pincer grip.
03:11And where its toes reach their limit,
03:13the chameleon's grasp is aided by a long, sturdy tail.
03:18Chameleons are an arboreal animal,
03:20and being able to maintain their position in the trees
03:24is really important.
03:25And prehensile tails really act like a fifth limb,
03:28if you would.
03:29When we think about humans and climbing trees,
03:32we always give ourselves a safety tether.
03:35We have a harness and we clip on
03:37to some type of attachment point.
03:39Really, the prehensile tail of a chameleon
03:41is a simpler thing in that it gives you
03:43an additional safety mechanism as a chameleon
03:46to make sure that if something goes wrong,
03:49you're still going to remain attached to the branch.
03:52Blending in is crucial to the chameleon survival.
03:55Lacking defensive capabilities like speed, armor, or venom,
04:00they must rely on stealth to keep them safe from predators.
04:05Chameleons are predators,
04:06but they're pretty low in the food chain.
04:08Trikes, hornbills, eagles, and castrels
04:10all prey on chameleons,
04:12as do snakes like the boomslaying and vinesnake.
04:15These are all highly capable predators,
04:18fast-moving, equipped with flight,
04:21lightning-fast strikes, or deadly poison.
04:24The chameleon would seem to be outmatched,
04:27except for one thing,
04:29its incredible defense of camouflage.
04:32Some chameleons look just like leaves.
04:34Their bodies can have a bit of a curve.
04:37Sometimes they have a ridge down their back
04:39to make it look like a variegated leaf.
04:41And some of them have the crest on their head
04:44that looks like the point of a leaf.
04:46The colors they can change into
04:47can look like variations of leaf color.
04:50They can make themselves look like shaded leaves,
04:53bright leaves,
04:54and sometimes they can even look like
04:56leaves that have some sunshine hitting it.
05:00Most chameleons' natural resting color
05:02is brown or green, depending on their habitat.
05:06Some chameleons also have horns and spikes on their back.
05:11In addition to providing some defense against predators
05:14or even other chameleons,
05:16they break up their silhouette
05:18and help them resemble the irregular shapes
05:20of twigs and branches.
05:24Even when they're on the move,
05:26the chameleon won't break character.
05:29Chameleons have a very interesting walk.
05:31They walk slowly, and as they walk,
05:34they kind of sway back and forth.
05:36It's like a little bit of a strut.
05:37They're trying to trick predators and prey
05:38to thinking that they're a leaf blowing in the wind.
05:41Even with all this,
05:43chameleons still need a leg up
05:45to stay ahead of their enemies.
05:47And this is where the most famous adaptation comes in,
05:51their ability to change color.
05:53But it doesn't work quite the way many people think.
05:57Chameleons have this reputation
05:59where people think that they can change
06:00into any background they want.
06:01For example, if they walk over a chessboard,
06:03they think that they can look like the chessboard,
06:05but that's just not true.
06:07But some species of chameleon can change color
06:08based on the type of predator that they detect.
06:11It turns out chameleons need
06:13a slightly different stealth strategy
06:15depending on who they're trying to hide from.
06:19Some animals use countershading for survival.
06:21For instance, a shark will be dark on the top
06:24and light on the bottom.
06:25That's advantageous because when you're looking
06:27from the ocean surface and you're looking down,
06:29you see the ground, which tends to be darker.
06:31However, if you're down below and you look up,
06:33you see the sunlight, you see the surface,
06:35which tends to be lighter.
06:36Chameleons can actually go one step further.
06:38They can change color depending
06:40on where the predator is situated.
06:42So if there's a predator that's coming from the top,
06:44it'll darken.
06:45And if the predator's coming from the bottom,
06:47it'll change into a lighter color.
06:48It's incredible that nature has engineered
06:50these species to change their color
06:52based on the predator that's looking at them.
06:56Chameleons lighten and darken their skin
06:58by manipulating special pigment cells
07:00called chromatophores.
07:03Chromatophores are found
07:04only in cold-blooded animals
07:06like octopus, reptiles, and some fish.
07:13Chameleon's skin has several layers of chromatophores.
07:16The bottom layer are melanophores,
07:18which contain the brown pigment melanin.
07:21This is really similar to the melanocytes
07:23that we have in our human skin,
07:25which affect the coloration of hair, skin, and eye color.
07:29These star-shaped cells can move
07:31to manipulate their concentrations of melanin
07:34to adjust the shade of a chameleon's skin,
07:38pulling it inward to lighten the lizard's hue,
07:40or pushing it out to the cell's extremities
07:43for a darker effect.
07:45They can do this rapidly,
07:46which allows for a rapid defense mechanism
07:49when the species are threatened.
07:52The exact biochemical mechanism
07:54that allows these changes to take place
07:57isn't fully understood,
07:58but it's believed to result from an interaction
08:01between the chameleon's hormones
08:03and autonomic nervous system.
08:05Imagine if you can turn a suntan on or off in an instant.
08:09That's what the chameleon does.
08:11Evidently, the chameleon's stealthy approach
08:14has been a successful strategy.
08:16After all, they've been around
08:18since the time of the dinosaurs.
08:20Based on fossil evidence,
08:22the chameleonidae family likely evolved in Africa
08:25around 100 million years ago,
08:28during the late Cretaceous period.
08:32For a family of animals to exist that long
08:35means they have to be doing something right,
08:37and stealth might very well have been
08:40one of the keys to their survival.
08:44But chameleons aren't just prey.
08:47They're formidable hunters, too.
08:49While keeping one eye open for predators,
08:52the other eye searches for their next meal.
08:54When we think about chameleon's eyes,
08:57they can act independently or together.
08:59And basically, that means they can be monocular
09:02or binocular.
09:04In monocular view,
09:06the eyes work independently of each other,
09:08and they're able to scan essentially 360 degrees
09:12around the chameleon looking for predators and prey.
09:16But then when the chameleon wants to focus on its prey,
09:20it uses its binocular vision.
09:22Basically, both eyes point at the prey,
09:24and by doing so,
09:26it can judge the distance to its prey.
09:28And that's the advantage of having binocular vision,
09:31is that you can judge distance.
09:32But how can a slow-moving chameleon
09:35catch a fast-moving bug
09:37without giving itself away
09:39and making it vulnerable to attack?
09:41The solution is the chameleon's incredible tongue.
09:45It allows the chameleon to launch an ambush
09:48while remaining hidden.
09:49As its weapon and its prime means of hunting,
09:53the chameleon has this exceptionally fast tongue.
09:57This tongue has a huge amount of muscles in it
10:01that allow it to propel it very quickly forward,
10:05and the sticky end of the tongue
10:07then sticks on its prey and pulls it back.
10:09It's really like a tethered harpoon
10:12that gets fired from the chameleon
10:14to capture its prey.
10:19The chameleon's tongue
10:20is a marvel of evolutionary bioengineering.
10:23It can be two and a half times
10:25as long as the animal's body
10:27and reach speeds of up to 8,500 feet per second.
10:31The chameleon tongue is fascinating.
10:35Inside the tongue is a long, skinny, tubular bone
10:39wrapped in layers of elastic tissue made of collagen.
10:43All of this is surrounded by a layer of muscle.
10:45The chameleon loads its tongue
10:47by squeezing the collagen fibers,
10:50compressing them like coiled rubber bands.
10:52When it launches the tongue,
10:54the collagen slides off the end of the bone and expands.
10:57This gives the tongue muscle
10:58a kind of springy turbo boost
11:01and allows it to achieve its incredible speed and power.
11:07After snagging its prey,
11:09the chameleon reels its tongue back into its mouth,
11:13where sharp teeth make quick work of its meal.
11:19For all its stealthy capabilities,
11:22there are times that the chameleon actually wants to be seen.
11:26Yet, why would a creature so intent on remaining hidden
11:29suddenly feel the need to reveal itself?
11:33Certain chameleons are capable of jaw-dropping changes
11:37in colors and patterns.
11:39Some, like the panther chameleon of Madagascar,
11:42are well known for their vibrant array of amazing colors.
11:47Chameleons can change color to display their emotions
11:50and communicate with other chameleons.
11:53Male chameleons are highly territorial
11:55and they'll engage in battles,
11:57displaying their colors to establish dominance.
12:00They'll face off with these dazzling colors,
12:03almost like warring billboards in Times Square.
12:06When the loser is determined,
12:08their color will fade and dull
12:10and they'll slink off in defeat.
12:12Additionally, chameleons can change color for thermoregulation.
12:16As cold-blooded animals,
12:18their body temperature is mainly determined by the sun
12:20and by changing to darker colors,
12:23they can absorb more sunlight and heat up their bodies.
12:26On the other hand, if it's getting too hot,
12:28they can use their color-changing abilities
12:30to reflect more sunlight and stay cool.
12:32So how does a chameleon change its color?
12:36It does so by manipulating a group of chromatophore cells
12:40called iridophores.
12:42Iridiophores are full of tiny, plate-like nanocrystals
12:46and these have the ability to reflect light
12:48in different wavelengths depending on how bunched up
12:51or spread apart they are.
12:53When a chameleon relaxes its skin,
12:56these nanocrystals are bunched together
12:58and this tends to reflect shorter wavelengths of light,
13:01like blues.
13:02But first, this blue light has to travel
13:05through a layer of yellow-tinted cells on its way out.
13:09Like mixing paint on a palette,
13:11the blue light pierces the yellow cells
13:14and creates the chameleon's signature green hue.
13:17But when danger strikes or the chameleon gets excited,
13:21something even more incredible happens.
13:23The nanocrystals move further apart
13:25and this is what reflects longer wavelengths of light,
13:28like red, yellow, and orange.
13:30This is what gives the chameleon its miraculous ability
13:33to change colors from greens and browns and blues
13:37to bright yellow and pink and orange.
13:41The chameleon has long inspired scientists
13:44trying to develop innovative
13:46and adaptive camouflage systems.
13:49Engineers and scientists look to nature
13:52to produce technologies.
13:54This is called biomimicry.
13:56We're mimicking what's done in biology.
13:59If you want to try and camouflage things,
14:02producing something that mimics a chameleon
14:05is really ideal.
14:06The color-shifting properties of the chameleon's skin
14:09has inspired scientists to invent fabric
14:12that changes color when pulled or stretched.
14:15These experiments are in the early stage,
14:18but you can imagine applications
14:19where fabrics change color for camouflage,
14:22fashion, or just to reflect the wearer's mood.
14:25The chameleon isn't the only stealth expert
14:28living among the trees.
14:33The ninja of the bird world, long-eared owls,
14:36are stealthy killers who strike silently and unseen.
14:40Hunting at night, the mice and voles they prey upon
14:43never see them coming.
14:45The long-eared owl is a stealth predator,
14:47and if you ever watch an owl hunt,
14:50you would have to watch them
14:51because you can't hear them.
14:57Owls are unique among birds of prey
14:59because they're capable of near-silent flight.
15:03They're considered the quietest birds in the world.
15:06Nature has basically engineered them
15:08to be the stealth fighters of the animal kingdom.
15:11Standing around 38 centimeters tall,
15:15with a wingspan of approximately one meter,
15:18the long-eared owl is itself vulnerable to attack
15:21from larger aerial predators,
15:24such as hawks and eagles.
15:27So how does this bird of prey evade detection
15:30while still ensuring a successful hunt of its own?
15:37The long-eared owl is particularly fascinating
15:39because not only does it have silent flight,
15:41but it has these anti-stealth capabilities
15:43to find hidden prey,
15:44and it can camouflage itself from predators.
15:47Long-eared owls are found
15:48across North America and Eurasia.
15:52They roost in dense forests with heavy canopies.
15:55They're also found at the edges of open fields
15:56and grasslands where they hunt.
15:58Sitting on a tree branch,
16:00its whitish-gray and tawny-brown speckled plumage
16:03allows the long-eared owl to nearly vanish
16:06against a background of bark and branches.
16:09They can make themselves look so skinny.
16:11They can make themselves look just like a branch.
16:14They have the coloration of wood,
16:15and if they close their eyes,
16:17you could not tell the difference
16:18if it was a branch or an owl.
16:21The long-eared owl is built for stealth.
16:24Even the tuft-like projections
16:26that give the owl its name
16:27are part of their disguise.
16:29Long-eared owls' ear tufts
16:31are actually not their ears.
16:33They're just feathers.
16:34Their ears are on the side of their head
16:36like all other birds.
16:37The feathers resemble twigs
16:39and help the owls blend in with the surrounding foliage,
16:43especially when they're standing in the tall, thin position.
16:47The camouflage hides them not only from predators,
16:51but conceals them from their prey.
16:56Although the long-eared owl is a master of stationary camouflage,
17:00it's in the air that its stealth capabilities come fully online.
17:05Long-eared owls will fly over grasslands
17:07in search of mice, shrews, voles, and other small mammals.
17:12They'll also eat small birds, bats, lizards, and snakes.
17:17Like a radar-avoiding aircraft,
17:20the owl flies low,
17:22sometimes barely more than two feet above the ground.
17:25Relying on its keen vision and superlative hearing,
17:29it zeroes in on its prey with razor-like precision.
17:33Watching an owl hunt is breathtaking.
17:36They'll glide silently across the field
17:39and then pivot, swerve, dive suddenly to catch some prey.
17:43And the long-eared owl can even do this in the dark.
17:47The long-eared owl's preferred time to hunt is at night,
17:50when it's practically invisible to prey that relies on sight.
17:54But mice and voles have keen hearing.
17:58Fortunately, long-eared owls
18:00are the undisputed masters of acoustical stealth.
18:04The sound of the long-eared owl in flight
18:06is about 18 decibels quieter than other birds.
18:15Aerodynamically, if you want to move really slow through the air,
18:18you need very large wings.
18:20The amount of lift produced by wings
18:23is a function of how fast the air flows over the wings.
18:27And the slower and slower you want to go,
18:30the larger your wing surface has to be
18:32because you're going to get less and less lift
18:34as the speed goes down.
18:36But the true secret of the owl's stealthy flight
18:39is hidden in the composition and structure
18:42of its flight feathers.
18:44When feathers rub against each other,
18:47especially if they're stiff,
18:49they vibrate and create noise.
18:51The velvety structure of the long-eared owl's feathers
18:55makes these feathers much quieter
18:58when they do move with respect to each other.
19:02Bird wings and airplane wings
19:04are designed to make air move faster
19:06over the top of the wing.
19:08When air moves faster,
19:10the pressure of the air decreases.
19:12This creates lift,
19:14which is what allows birds and airplanes to fly.
19:17But when the upper and lower streams of air
19:20meet behind the wing,
19:21they create turbulence.
19:23And this produces sound,
19:25the characteristic whoosh of a bird in flight.
19:30Nature has provided the long-eared owl
19:32with an innovative solution to this problem.
19:35The long-eared owl has serrated
19:37or comb-like feathers
19:39at the leading edge of its wings.
19:41These comb-like or serrated structures
19:44break the flow of air up into smaller streams.
19:48Because the feathers at the trailing edge
19:50are very velvety and downy,
19:52basically those fine little bits of feather
19:55absorb sound
19:57rather than allowing aerodynamic sound to develop.
20:01A pinnacle of aeronautical stealth,
20:04it's no wonder human engineers
20:06have long looked to owls
20:07as a model for aviation design.
20:09A lot of what we're trying to do
20:12in designing airfoils and wings
20:13is make them more efficient.
20:16And the owl's ability to be silent
20:19is really a testament
20:21to how efficiently their wings operate.
20:24The long-eared owl's
20:26exquisitely bioengineered stealth capabilities
20:28also have applications outside of flight.
20:32Engineers look to birds like the long-eared owl
20:35to help innovate in airfoil design.
20:40Aerofoils refer to things
20:41that have the shape of wings
20:43and wind turbines are a great example of that.
20:47One of the drawbacks of wind turbine blades
20:49is that they make a large whooshing sound
20:51as they go by.
20:56That's a loss of energy.
20:58Not only is it a loss of energy,
20:59but it's quite annoying to residents in the area
21:03and potentially a distraction for animals
21:05that may drive local wildlife away.
21:08Putting serrated leading edges
21:10on wind turbine blades
21:12like owls have on the leading edge of their wings,
21:14we can make them not only more efficient,
21:17but quieter.
21:18The long-eared owl's incredible ability
21:21to fly silently
21:22means it can employ another one of its superpowers,
21:26super hearing.
21:27Quiet flight means there's no acoustical noise
21:29to hamper the long-eared owl's hearing.
21:31The long-eared owl's hearing isn't only precise.
21:34It's ten times more sensitive
21:36than human hearing
21:37in the middle and upper frequencies,
21:40exactly the range
21:41that its prey's movement
21:42and vocalizations fall into.
21:46Owls are nocturnal animals,
21:47so they can't rely solely on their sight
21:50to find their prey.
21:51It's just too dark.
21:53So owls rely on their hearing.
21:55The feathers on the long-eared owl's face
21:58act very much like a parabolic dish.
22:01Basically, the feathers funnel sound to the ears.
22:05In addition, the ears are offset vertically
22:08on the owl's head.
22:10This basically gives the owl
22:13better spatial resolution vertically
22:15to determine where its prey is.
22:18So when the owl changes the position of its face,
22:22it can detect increases or decreases
22:24in the sound level.
22:29So if the owl locates a prey,
22:34it can actually,
22:35by moving its head slightly in all directions,
22:39basically determine the location of that prey
22:42so that when it does choose
22:44to take its flight to attack the prey,
22:47it's well locked in it
22:48and it knows where it needs to go.
22:50Once this bird is locked in
22:52on the source of its meal,
22:54it swoops in for the surprise attack,
22:57a silent hunt unlike any other.
23:07The long-eared owl's mastery
23:09lies in this hushed approach,
23:11disappearing into the dark canopy of the trees
23:15until it's time to strike.
23:18But far from the dense forests
23:21and open fields
23:22where these clever birds hunt,
23:25another stealth expert contends
23:28with an entirely different environment,
23:31one barren and uniform
23:34where any wrong move
23:35could be spotted with ease.
23:38This sneaky mammal uses the winter wasteland
23:41to its advantage,
23:43masterfully matching itself to the snow.
23:46But what is one to do
23:47when the winter snow melts
23:49and spring arrives on the tundra?
23:54Arctic foxes sit in a tricky spot
23:56as stealth experts.
23:58Because they don't hibernate,
23:59they need to hunt year-round,
24:01and so they rely on their camouflage
24:02to catch their prey.
24:04But they're also prey for larger animals
24:06like bears, wolves, golden eagles,
24:09even their larger cousins, the red fox.
24:12Because of this,
24:13they need to use their camouflage
24:15both for offense and defense.
24:17The Arctic fox solves these challenges
24:20by changing its coat of fur.
24:22So if one coat doesn't work,
24:24why not use two?
24:25The Arctic fox can change the color
24:27and thickness of its fur
24:28in different seasons.
24:29Just like how we might switch
24:31a heavy parka in the winter
24:33to a light jacket
24:34in the spring and summer.
24:36This amazing ability
24:38is called seasonal coat color malting,
24:40and it's the key
24:41to what makes the Arctic fox
24:43an elite stealth predator
24:45and survivor
24:46in a harsh and unforgiving biome.
24:51Smaller than their southern red cousins,
24:53Arctic foxes range in size
24:55from 46 to 68 centimeters.
24:58and weigh from 3 to 8 kilograms.
25:01The Arctic fox is found
25:02in tundra and coastal regions
25:04across its circumpolar range,
25:06including the northernmost parts
25:08of North America,
25:09Europe, Asia, Greenland, and Iceland.
25:13There are few places to hide
25:15in the Arctic tundra,
25:16even in the summer.
25:18Here, survival depends
25:20on a single desperate strategy,
25:22becoming invisible.
25:25In the spring and summer months,
25:26the face, legs,
25:28and upper parts of the Arctic fox
25:30are covered a gray-brown,
25:31and its abdomen
25:32is a yellowish-white.
25:34This allows it to easily blend in
25:36into the rocks, dirt, and sand
25:38of the tundra environments.
25:40But as the seasons begin to change,
25:42the landscape is transformed.
25:45The muted grays and browns
25:47slowly surrender
25:48to the bright white snow of winter.
25:51Luckily, the Arctic fox
25:53is already one step ahead.
25:55From September to October,
25:57the Arctic fox begins its autumn molt.
26:00White fur grows in,
26:01and the darker fur coat falls out.
26:03This new coat allows the Arctic fox
26:05to practically vanish
26:07into the snowy-white landscape.
26:12There's a lot of analogies
26:13between the Arctic fox
26:14and combat gear,
26:16in that if you look at soldiers
26:18that are deployed to the Arctic,
26:20they'll wear very, very white snowsuits
26:23to help them blend in
26:24with their environment.
26:25And soldiers deployed to a desert,
26:28they'll wear very brown,
26:30very beige outfits.
26:32Light camouflage donned by the military,
26:34the Arctic fox uses its coat
26:37to seamlessly blend
26:38into the background.
26:40But this layer of fur
26:42does far more than cloak
26:44this creature from prying eyes.
26:46It also offers protection
26:48from the harsh Arctic winter environment,
26:51where temperatures can reach
26:52an almost unbearably cold
26:54minus 50 degrees Celsius.
26:57In the dead of winter,
26:59Arctic foxes must endure
27:01incredible temperature differences
27:03of almost 100 degrees Celsius
27:05between their internal core temperature
27:07and the temperature outside.
27:10Fortunately, Arctic foxes
27:12wear the warmest coats
27:13in the animal kingdom.
27:15Their winter fur is longer
27:16and twice as dense
27:18as their summer coat.
27:19The coat is formed
27:21of two separate layers of fur.
27:23The long outer layer
27:25is called the guard hairs.
27:26It overlaps a thicker layer
27:28called the undercoat.
27:29This works exactly
27:31like a winter parka,
27:32which combines
27:33an outer protective layer
27:35with an insulating inner layer.
27:37They even wear little boots,
27:39which is just adorable.
27:42Their foot pads
27:43are covered in fur,
27:44which is unique
27:44among wolves, dogs,
27:46and other foxes.
27:47Even the coat's white color
27:49helps keep the fox warm.
27:51Because it lacks pigment,
27:53white hair contains
27:54extra space in the cells
27:55to trap air.
27:57This makes it more efficient
27:58at retaining heat
27:59than darker hair.
28:01But how does the Arctic fox
28:02know when to change
28:03its dark summer coat
28:04for a light winter one?
28:06And how does it do it?
28:08It's not the cold
28:09or the snow
28:10that causes the Arctic fox
28:11to change the color
28:12of its fur.
28:12It's actually the amount
28:14of light
28:14or the lack of light.
28:16Shorter daylight hours
28:17stimulates the secretion
28:18of hormones,
28:19which promote the growth
28:20of white hair
28:21and the loss
28:22of a summer coat.
28:23Here's how it works.
28:26Daylight affects
28:27the production
28:27of the hormone melatonin,
28:29which occurs
28:30in the pineal gland
28:31located deep
28:31in the fox's brain.
28:33The more hours
28:34of darkness,
28:35the more melatonin
28:37is produced.
28:38As the days shorten
28:39with the oncoming
28:40of winter,
28:41increased melatonin
28:42reduces the production
28:43of another hormone
28:44called prolactin.
28:48Prolactin is produced
28:49by the pituitary gland
28:51and is connected
28:52to hair growth
28:53and loss.
28:56Basically,
28:57an Arctic fox
28:57has a built-in
28:58light sensor.
28:59Instead of turning
29:00the lights on
29:00when it gets dark,
29:01it tells the fox's
29:02hormonal system
29:03to produce white fur.
29:04And when light
29:05returns in the spring,
29:06it tells the fox's fur
29:07to turn darker
29:07for the summer.
29:08Now draped
29:09in its perfectly
29:10timed disguise,
29:11the Arctic fox
29:12is ready to continue
29:14its ongoing hunt.
29:16Stealth is the key
29:17to the Arctic fox's
29:18hunting strategy.
29:20Foxes are omnivorous
29:22and very opportunistic
29:24feeders.
29:24They'll basically eat
29:25anything they can get
29:26their little paws on,
29:27from berries,
29:28eggs, insects,
29:30to birds, mice, voles.
29:33They'll even eat carrion
29:34left by bears
29:34or other hunters
29:35if they have a chance.
29:36Yet even for this
29:38cunning predator,
29:39the hunt is far
29:40from guaranteed.
29:42Some prey,
29:43like certain species
29:44of lemming
29:45and many northern stoats,
29:47have also evolved
29:48the ability
29:48to change color
29:49with a shifting season.
29:53Their small size
29:54lets them disappear
29:55beneath the snow,
29:58tunneling deep
29:59to evade capture.
30:01So, to outsmart
30:03these crafty critters,
30:05the Arctic fox
30:05has developed
30:06its own arsenal
30:07of anti-stealth adaptations.
30:10The Arctic fox
30:12in the winter environment
30:13is an environment
30:14that's all snow.
30:16So the Arctic fox
30:17really can't hunt
30:18by sight.
30:19It really has to rely
30:20on its other senses.
30:22So the Arctic foxes
30:23can smell their prey
30:24and get in relatively close
30:26by sensing their prey
30:27by smell.
30:28But then once they're there,
30:30they can't see it.
30:31So they need another mechanism
30:33to determine exactly
30:34where their prey is.
30:35The Arctic fox
30:38has highly directional
30:39and sensitive hearing.
30:41Just like a parabolic microphone
30:43uses a dish
30:44to focus sound waves
30:45and amplify faint noises,
30:47the Arctic fox's
30:48small, rounded ears
30:50minimize wind interference,
30:52making it easier
30:53to focus on the sound
30:55that matters.
30:56By rotating the ears
30:58and moving with respect
31:01to their prey,
31:02the Arctic fox
31:03can very accurately determine
31:05where their prey is
31:06even up to a half
31:07to three quarters
31:08of a meter
31:09below the snow.
31:10Once they zero in
31:11on their prey,
31:12they pounce.
31:13The Arctic fox
31:14has a unique strategy
31:15for hunting
31:16that's called mousing.
31:18Essentially,
31:19they'll jump
31:19several feet in the air
31:20and dive face first
31:22into the snow.
31:23The fox's rounded snout
31:25lets it penetrate the snow
31:26without resistance
31:28and without injury
31:29to itself.
31:30Yet,
31:30even as it stalks
31:31its prey,
31:32the Arctic fox
31:33must remain vigilant.
31:35In this environment,
31:37every hunter
31:38can just as easily
31:39become the hunted.
31:41Natural predators
31:42are a threat year-round.
31:44Basically,
31:44everything bigger
31:45than this fox
31:46is trying to eat it.
31:47Golden eagles,
31:48wolves,
31:49grizzly bears,
31:50polar bears,
31:51and wolverines
31:52are all constant threats
31:54on the winter landscape.
31:56Golden eagles
31:57are a particular risk.
31:58They can spot an animal
31:59the size of a fox
32:00from up to 5 kilometers away.
32:03If they see a fox,
32:04they'll hover above.
32:06They'll wait until
32:06the fox is distracted
32:07or looking down
32:08and then dive at it,
32:10reaching speeds
32:11of up to 193 kilometers per hour.
32:14These eagles have enough strength
32:16in their claws
32:17to puncture a car tire.
32:18An arctic fox
32:20doesn't stand a chance.
32:25Thanks to the stealthy benefits
32:27of their seasonally appropriate attire,
32:30adult arctic foxes
32:31are well-equipped
32:32to deal with dangerous predators
32:33and elusive prey.
32:35But what about pups
32:37who are just starting out?
32:39Pups are born in late May
32:40and early June.
32:42They're born blind,
32:43deaf,
32:43and toothless,
32:44so they're basically
32:45as helpless as can be.
32:47They don't start to fend
32:48for themselves
32:48until about 3 months old.
32:50A golden eagle
32:51can easily carry away a pup.
32:53Fortunately,
32:54the arctic fox's den
32:56is constructed
32:57with stealth in mind.
32:58Female foxes
32:59will stay in this den
33:00with the pups
33:01until they're old enough
33:02to venture out.
33:03During this time,
33:04they'll at least be safe
33:05from all aerial attacks.
33:06The dens often form
33:08a complex maze of tunnels,
33:10sometimes spreading
33:11as large as a football field.
33:13The dens have multiple entrances.
33:15Up to 150 have been recorded,
33:18which gives them plenty
33:19of opportunity
33:19to slip in and out unnoticed
33:21by both predators and prey.
33:23Foxes will return
33:25to the same den
33:26year after year.
33:27It's believed
33:28that some dens
33:29have been in use
33:30for centuries.
33:31Talk about a heritage home.
33:33The arctic fox's
33:35stealthy approach
33:36to offense and defense
33:37has made it
33:38a northern success story.
33:40But this animal
33:41now faces
33:42an unprecedented test.
33:44The arctic foxes,
33:46when they're in their winter coat
33:47with their white, white fur,
33:50normally would blend
33:51into a white landscape,
33:53assuming there's snow
33:54on the ground.
33:55And we all know
33:56with climate change,
33:56we're starting to see
33:57species like the arctic fox
33:59not able to camouflage
34:00as well
34:01because there's less snow.
34:02So they're finding
34:03a hard time
34:04being able to catch prey.
34:05Prey can see them
34:06coming a mile away
34:07if the ground is brown
34:09and they're bright white.
34:11While a changing climate
34:13poses a real threat
34:14to this small mammal,
34:16evolution has also equipped it
34:17with the valuable trait
34:18of adaptability.
34:21As it contends
34:22with these environmental changes,
34:24scientists hope
34:25it will unlock
34:26surprising new strategies,
34:28ensuring it can continue
34:30moving undetected
34:31against both food
34:33and foam.
34:40The arctic fox's challenge
34:42of transforming
34:43against shifting terrain
34:44is one that echoes
34:45across the animal kingdom.
34:47And while some creatures
34:49prefer to blend
34:49into distant vistas,
34:51others might be hidden
34:53right below your feet.
34:55When it comes to mimicking
34:57the twigs and leaves
34:58of the forest floor,
34:59none is more talented
35:01than the stick insect.
35:03In fact,
35:04stick insects may be
35:05the true champion
35:06of Krypsis,
35:07the ability to blend
35:08into the background.
35:10Stick insects
35:11are incredible.
35:13They are found
35:13on every single continent
35:15except Antarctica.
35:16There's over 3,000 known species
35:18of these animals
35:19and they cover a huge variety
35:21of shapes and sizes.
35:23Some have evolved
35:24to look like moss
35:25or lichen,
35:26and some have even evolved
35:27to look like different types
35:29of leaves
35:29in their environments.
35:31Your classic stick insect
35:33looks like a twig or a branch.
35:35It is perfectly adapted
35:36to blend into its surroundings.
35:38It's either brown
35:39or maybe green in color.
35:41It has an elongated body
35:43with six skinny, skinny legs
35:45hanging off of it.
35:47Their size ranges
35:48from only a few centimeters
35:49in length
35:50to truly nightmarish proportions.
35:54Stick insects
35:54might look really freaky,
35:56a bit alien-like,
35:58but they're actually
35:58very peaceful.
35:59They're herbivores.
36:00They eat leaves.
36:02These solitary creatures
36:03form the phasmid order
36:05of insects.
36:06The word phasmid
36:07comes from the Greek word
36:09phasma,
36:09which means phantom.
36:11And like ghosts,
36:12stick insects
36:13have the ability
36:14to seemingly disappear.
36:16Stick insects
36:17are really amazing.
36:18They just blend in
36:19with their environment
36:20so perfectly.
36:21They're kind of
36:22the ultimate camouflage.
36:24Over my life,
36:25I've been lucky enough
36:25to see many of them,
36:27but it's only in situations
36:28where they're no longer
36:30in their prime habitat.
36:31They've fallen out
36:32of the tree
36:32onto a walkway
36:34or onto a deck
36:35where they're quite obvious.
36:37But I don't think
36:38I've ever actually
36:39found one
36:39when it's been in a tree.
36:41They just blend in
36:42so perfectly.
36:43Stick insects depend
36:45on their brilliant disguises
36:46because they're a popular item
36:48on the dinner menu
36:49for so many other animals.
36:51They have to watch out
36:52for small mammals,
36:53reptiles, birds,
36:55you name it.
36:56Lots of things
36:57like to eat stick insects.
37:00Perfectly evolved
37:01to fill their niche
37:02as nocturnal herbivores,
37:04stick insects
37:04have been stealthily
37:05fooling predators
37:06for over 100 million years.
37:09The first fossilized record
37:10of a stick insect
37:11is from the Cretaceous period
37:13about 126 million years ago.
37:15It's believed
37:16that stick insects
37:17evolved their stealthy form
37:19around the time
37:20that the first
37:20flying birds evolved.
37:22It's thought
37:23that these early birds
37:24hunted insects
37:26just like they do today.
37:27Stick insects
37:28literally look
37:29like walking sticks
37:30and leaps.
37:31These distinct,
37:33stealthy features
37:34would have allowed
37:34phasmids to survive
37:36until the present day.
37:38Stealth is more
37:39than just a means of defense
37:41for stick insects.
37:43It's an entire way of life.
37:46Even their eggs
37:47are camouflaged.
37:48Their eggs tend to look
37:49like teensy-tiny little scenes.
37:51A female will lay
37:52between 2 and 15 eggs
37:54every single night.
37:56Some stick insect mums
37:58will hide their eggs
37:59underneath little leaves.
38:00Other ones will just
38:01scatter them along the ground.
38:03This is actually
38:04an excellent strategy
38:05for ensuring
38:06some of the babies survive.
38:08Even if a bird
38:09or other insect
38:10finds some of the eggs,
38:12they won't get
38:12the entire clutch.
38:14The eggs are coated
38:16with a hard substance
38:17called calcium oxalate crystals.
38:19This is the same substance
38:21that makes up kidney stones.
38:23This coating allows
38:24the eggs to survive
38:25in stomach acid,
38:26so they may hitch a ride
38:28in the digestive tract
38:30of a bird.
38:31Eggs can travel
38:32hundreds of kilometers
38:34this way.
38:35Once they hatch,
38:36stick insect juveniles,
38:38called nymphs,
38:39are stealthy
38:40from the get-go.
38:41Most juvenile stick insects
38:42are born as tiny versions
38:44of their adult selves.
38:46They're born camouflaged.
38:48Stick insects
38:49don't just depend on shape
38:50for their disguises.
38:51They have the incredible ability
38:53to match their color
38:54to their surroundings
38:55by literally chewing
38:57the scenery.
38:58Stick insects eat the leaves
38:59off of trees, shrubs,
39:01and plants.
39:01In so doing,
39:02they eat a pigment
39:03called carotenoids.
39:04When they eat that carotenoid,
39:06it turns them the same color
39:07as the leaf.
39:08If the leaf is green,
39:09they will turn
39:10a green color.
39:11It's very similar
39:12to if humans eat carrots,
39:14and they eat too many carrots,
39:15their skin will turn
39:16an orange tinge.
39:18So how do these
39:19conscious eaters make use
39:20of the carotenoids
39:21they consume?
39:23In the summer,
39:24stick insects accumulate
39:25a carotenoid called beta-carotene,
39:27which gives them
39:28their green color.
39:29In the fall,
39:29some stick insects
39:30will convert the beta-carotene
39:32into a reddish pigment,
39:33which allows them
39:34to blend in
39:35with the autumn foliage.
39:37The problem, however,
39:38is that leaves and sticks
39:40don't walk around,
39:41and stick insects
39:42can give themselves away
39:43if they move.
39:45To counter this,
39:46evolution has bestowed
39:47an unusual superpower.
39:49Stick insects can freeze
39:51and remain motionless
39:52for long periods of time.
39:54This is called catalepsy,
39:55and it can confuse predators
39:57who often use motion
39:58to zero in on their prey.
40:01Stick insects can even
40:02take their immobility
40:04one step further.
40:05When they detect a predator,
40:07some stick insects
40:08will fall off a branch
40:09and play dead.
40:10This behavior
40:11is called phanatosis.
40:12This is an effective
40:14defense strategy
40:14because lots of animals
40:16don't like to eat dead prey.
40:17But staying still
40:19on a leaf or the ground
40:20for too long
40:21can pose a risk,
40:22particularly if the world
40:24around you is moving.
40:25When you see a stick insect
40:27and you see it actually move,
40:29they don't really walk
40:30in the traditional sense.
40:32They kind of rock,
40:33and it very much looks like
40:35a twig blowing in the wind
40:37in that they're moving
40:38back and forth.
40:40When we think about
40:41the gait of most animals,
40:43especially multi-legged animals,
40:46almost invariably,
40:48there's a pattern
40:48to the movement
40:49of the legs.
40:50Stick insects
40:51don't follow that pattern
40:53in that they can move
40:54each of their legs
40:55independently.
40:57It's almost like
40:58each leg of the stick insect
40:59is moving
41:00and thinking for itself.
41:03Scientists have turned
41:04to stick insect locomotion
41:05as a model for six-legged robots
41:08called hexapods.
41:10When we think about
41:11robotic-limbed vehicles,
41:14it's very difficult
41:15for them to actually move.
41:17And the act of moving
41:19more than one leg at a time
41:21is complex technologically
41:24to synchronize it.
41:25So when we design robots,
41:27we use the stick insect's
41:29mode of locomotion
41:31in that we tend
41:32to want to move
41:33one leg at a time
41:34because that way
41:35we ensure stability
41:37for the robot as a whole.
41:39Shape, color,
41:40and movement
41:41all make stick insects
41:43masters of krypsis.
41:45But if a predator
41:46sees through
41:47their stealthy defenses,
41:48some stick insect species
41:50still have a few surprises
41:51up their sleeves.
41:54The Australian walking stick
41:56has an incredible defense.
41:57It can curl its tail up
41:59to look like a scorpion's tail
42:00if it's threatened
42:01by a potential predator.
42:03Several species of stick insects
42:05actually have some wings.
42:07They're weak flyers,
42:08but these wings
42:08are often brightly colored
42:10and they can be used
42:11in predator defense.
42:12If the stick insect
42:13is detected by a predator,
42:15it can flash the bright colors
42:17and startle the predator,
42:18allowing the stick insect
42:19a little bit of time
42:20to escape.
42:21This is called
42:22a startle display.
42:23And if a predator
42:24is still determined
42:25to take a bite,
42:26some stick insects
42:28can even deploy
42:29a chemical defense.
42:30Several species
42:31of stick insects
42:32can actually excrete chemicals
42:34when threatened
42:35by a predator.
42:36For example,
42:37the devil rider stick insect
42:38has glands
42:39at the front of his thorax
42:40from which it can shoot
42:42chemicals
42:42that are noxious to predators.
42:45It's almost like
42:45having a built-in bottle
42:47of pepper spray
42:47for defense.
42:50Having chased off
42:51its attacker,
42:53the stick insect
42:53can go back
42:54to doing what it loves most,
42:56munching on leaves
42:57and stealthily blending
42:59into the lush foliage
43:00it calls home.
43:05Just as the stick insect
43:07disappears among twigs
43:08and leaves,
43:09below the surface
43:10of the ocean
43:11lives a creature
43:12that takes its stealthy
43:13lifestyle
43:14to a whole other level.
43:17This may look like
43:18a piece of seaweed
43:19but it's not.
43:21It's an animal
43:22called the leafy sea dragon
43:23and it's one of the
43:25stealthiest
43:25and strangest looking fish
43:27on earth.
43:28Leafy sea dragons
43:29look crazy.
43:31They are actually a fish.
43:33They're in the group
43:34of bony fish,
43:34osteocthes,
43:35as opposed to
43:36chondrocthes,
43:37which would be
43:38our carnilaginous fish,
43:39our sharks,
43:41rays,
43:41and ratfish.
43:43But they are a fish.
43:45They're a bony fish
43:46just like a trout is
43:47but they are so highly
43:48adapted to camouflage
43:50that they look
43:51the way they do.
43:52Leafy sea dragons
43:53are masters
43:54of marine mimicry.
43:55They essentially evolved
43:56to look like
43:56floating pieces of seagrass.
43:58A relative of seahorses
44:00and pipefish,
44:02the leafy sea dragon
44:03is found in only
44:04one place in the world,
44:06the temperate waters
44:08off the coast
44:08of southern Australia.
44:10Leafy sea dragons
44:11live on rocky reefs,
44:13seaweed beds,
44:14or seagrass meadows.
44:16They're found at depths
44:17between 3 meters
44:17and 50 meters.
44:19They're solitary creatures.
44:20They live alone.
44:21They don't travel
44:22very far from where
44:22they were born,
44:23maybe a few hundred meters.
44:25Like seahorses,
44:26the male sea dragons
44:26carry the eggs.
44:27They incubate the eggs
44:28on a specialized
44:29sponge-like section
44:30of the skin
44:31under the tail
44:31called the brood patch.
44:35Once the eggs hatch,
44:37these young sea dragons
44:38will be forced
44:39to contend
44:40with dangerous seas
44:41where predators lurk
44:42around every rock
44:43and coral.
44:46Although leafy sea dragons
44:48have spear-like spines
44:50and are covered
44:50in bony armor-like plates,
44:52they lack other means
44:53of self-defense,
44:55such as sharp teeth
44:56or speed.
44:58Instead,
44:59they rely almost entirely
45:00on stealth
45:01to keep them safe.
45:03Nearly every aspect
45:04of this animal,
45:05from the way it looks,
45:05from the way it moves,
45:06from the way it eats,
45:07has evolved to hide itself
45:09from predators and prey.
45:11In fact,
45:12their disguise
45:12is so effective
45:13that leafy sea dragons
45:15seem to have outsmarted
45:16every potential predator.
45:18The leafy sea dragon
45:19shares its habitat
45:20with some formidable predators.
45:22Sharks,
45:23harlequin fish,
45:25groupers.
45:25But as far as
45:26marine biologists are aware,
45:28none of these feed
45:29on the leafy sea dragon.
45:31Obviously,
45:32looking like kelp
45:33pays off.
45:34Even though we don't know
45:36of any modern predators
45:37for the leafy sea dragon,
45:38there must have been
45:40very strong predation pressure
45:42on them in the past
45:43to drive such drastic
45:45physical features today.
45:48So,
45:48what makes the leafy sea dragon
45:50such a uniquely successful
45:51stealth expert?
45:53Sea dragons belong
45:54to a group called
45:55Tilios.
45:56They represent about
45:5796% of fish on the earth,
45:58anywhere from minnows
45:59to marlins.
46:01But they have evolved
46:02a radically different
46:03body shape
46:03from the regular fish design.
46:05They have a long,
46:06thin body
46:06with a kinked spine
46:07that looks like
46:08a stalk of seaweed.
46:09Instead of a jaw,
46:10they actually have
46:10a long snout,
46:11which adds to the illusion
46:12that they're a plant
46:13and not an animal.
46:14Instead of scales,
46:16sea dragons are covered
46:16with rigid plates
46:17that are made of bone,
46:18which limit their
46:19flexibility and movement,
46:20which gives them
46:21the appearance of a plant
46:22rather than a fish.
46:24Their most distinguishing
46:25feature are the leaf-like
46:27appendages
46:27that resemble kelp fronds.
46:29These aren't fins,
46:31but modified spiny projections
46:33made of bone.
46:34The lobes at the end
46:36are filled with collagen
46:37and connective fibers
46:38that make them look
46:39as flexible as real seaweed.
46:42Even their color
46:43is a perfect match
46:44for their surroundings.
46:45And like chameleons
46:47and stick insects,
46:48leafy sea dragons
46:49can manipulate pigment
46:50in their chromatophore cells
46:52to blend in better
46:53with the background.
46:57Mimicking its backdrop
46:58comes easy.
47:00But how does this fish
47:01move from place to place
47:03across the open ocean floor
47:04without drawing attention?
47:07Sea dragons use
47:08their pectoral fins
47:09and their dorsal fin
47:10for propulsion.
47:11They basically undulate
47:13these transparent fins
47:14to allow them to move.
47:16To maintain their position
47:18in the water column,
47:19they use an air bladder.
47:20The sea dragon's pectoral fins
47:22undulate it
47:2325 to 30 times a second
47:25gives them the ability
47:26to propel themselves
47:27through the water.
47:31Small fins mean
47:33the leafy sea dragon
47:34moves very slowly.
47:35But they also allow
47:37for very precise movement.
47:39Sea dragons
47:40are really interesting.
47:42Where fish are kind of
47:42like zeppelins
47:43that use their tail
47:44for propulsion
47:45and their pectoral fins
47:46for steering,
47:48sea dragons are more
47:49analogous to helicopters
47:50in that they use
47:51their pectoral fins
47:53to kind of hover
47:54in the water column.
47:56This undulating style
47:58of movement,
47:59common to both
48:00the leafy sea dragon
48:01and the weedy sea dragon,
48:02is so efficient
48:03it has inspired
48:05novel designs
48:05for aquatic robots.
48:08Scientists are starting
48:09to construct
48:10biomimetic robots,
48:11robots that mimic
48:13creatures like
48:13the leafy sea dragon.
48:15Traditional propeller-based
48:17marine robots
48:18can get tangled
48:19in sea weed
48:19and they can damage
48:21sea life.
48:22At slow speeds,
48:23they're not very
48:24maneuverable or efficient.
48:27Biomimetic robots
48:28that can mimic
48:29the undulating movement
48:30style of the leafy sea dragon
48:32can use less energy
48:33and be more precise
48:35at those slower speeds.
48:36This makes them useful
48:38for underwater research,
48:39mining, rescue,
48:41and exploration.
48:43But don't let their
48:44covert appearance
48:45fool you.
48:47Stealthily concealed
48:49among swaying kelp beds,
48:50this delicate-looking
48:52species
48:52are actually
48:53deadly ambush hunters.
48:56Sea dragons feed
48:57on larval fishes
48:58and amphipods,
49:00like small,
49:02shrimp-like crustaceans
49:03called sea lice.
49:04They'll hunt
49:05by lying in wait
49:06and waiting for prey
49:07to float on by.
49:09Like chameleons,
49:10they have independently
49:11mobile eyes,
49:12so they can keep
49:13a watch for prey
49:14in all directions.
49:18All sea dragon species
49:19hunt the same way,
49:21maneuvering themselves
49:22close,
49:23then striking
49:24with their tube-like mouths.
49:30Because the sea dragon
49:31is so adapted
49:32to camouflage,
49:33they don't have
49:34the moving jaw
49:35like a lot of other fish do.
49:37They have this long snout
49:38that looks like a straw
49:40and they use it
49:41to suck in their prey.
49:43Sea dragons
49:44are a marvel
49:45of evolutionary engineering
49:46and the genetic blueprint
49:48they are built from
49:49may explain
49:50their uniquely
49:50stealthy adaptations.
49:52The leafy sea dragon
49:54has been described
49:54as evolution gone crazy.
49:57They have a very unusual
49:58and interesting genome.
50:00They lack several
50:01key development genes
50:02that are responsible
50:03for growing things
50:04like teeth
50:04and face structure.
50:05That is why the sea dragon
50:06has a fused jaw
50:07and no rips
50:08but they also have
50:09an abundance of
50:10what are called
50:10transposins
50:11or jumping genes.
50:13These genes move around
50:14in the genome.
50:15They cause genetic diseases
50:16and mutations
50:17but they are also
50:18responsible for rapid
50:19genetic change.
50:28The leafy sea dragon's
50:29unique genome
50:30might explain
50:31why they developed
50:32such radically
50:33unusual characteristics
50:34in a relatively short time.
50:37They seem to have
50:38branched off
50:39from more conventional
50:40looking fish
50:40in the last
50:4150 million years or so.
50:43This is a pretty
50:44short amount of time
50:45at least in evolutionary terms
50:47for such a strange
50:49and unique looking creature.
50:52Sea dragons
50:53are so well equipped
50:54to hide
50:55that an entirely new species
50:57was only recently discovered.
50:58A new species
50:59of sea dragon
51:00called the ruby sea dragon
51:01was only spotted
51:02in the wild
51:02for the first time
51:03in 2015.
51:04That brings the total number
51:05of known sea dragon species
51:07to three.
51:08But they're so good
51:09at hiding
51:10that it's possible
51:11that there are species
51:11that we don't even know of yet.
51:13Could there be more
51:14of these tantalizing creatures
51:16hidden among our waters?
51:18One of the most
51:19stealthily camouflaged
51:20animals on Earth,
51:21the leafy sea dragon,
51:23is living proof
51:24of nature's
51:25inexhaustible creativity
51:27when it comes
51:28to survival
51:29and adaptation.
52:00Another nice
52:00journey
52:00is
52:00the
Comments