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00:10The gigantic giraffe boasts some impressive stats.
00:21It's the tallest mammal on earth, nearly three times the height of a professional basketball
00:29player. And as heavy as a car. But have you ever considered what it takes to feed such a massive
00:39frame? Or how this giant overcomes the rather difficult problem of drinking?
00:59Being one of Earth's big beasts has its advantages, but also comes with sightable challenges.
01:12How they overcome life's big problems can be truly jaw-dropping. Whether it involves a total meltdown,
01:29a brutal battle, or maintaining their own air conditioning. It seems they've got it licked.
01:40It's time to meet a remarkable group of animals. Nature's biggest beasts. From the behemoths of a bygone age.
01:54To the leviathans of our modern world. It's the biggest beasts that capture our imagination.
02:08But size is relative. And there are surprising giants lurking in places you might not expect.
02:20Animals whose claim to fame is simply being amongst the biggest of their kind.
02:30But whether they're a titan in a tiny world, or a giant among other giants, they all share the same
02:38basic challenges.
02:42They all share the same things.
02:43Moving their massive bodies.
02:47Surviving extreme temperatures.
02:52Having huge babies.
02:57And not least, the need to eat.
03:01A lot.
03:17Let's begin with an incontestable big beast.
03:26Those giraffes.
03:27Those giraffes.
03:39Nearly six metres of mostly leg and neck.
03:44Perched on feet the size of dinner plates.
03:57Being head and shoulders above the rest does have its perks.
04:04Seeing for miles around.
04:15Reaching 35 miles an hour with its ground-eating strides.
04:29Reaching 35 miles an hour with its ground-eating strides.
04:34Means it can reach the food its competitors can't.
04:46Just as well.
04:48Because a giraffe has a super-sized appetite.
04:53Which it needs to satisfy by eating foliage.
04:57Foliage.
05:02To get enough nutrients from just a few leaves per bite, a large male must consume up to 65 kilograms
05:09daily.
05:14To eat through that many leaves a day can take up to 18 hours.
05:23But never mind feeding.
05:28In dry times, a giraffe can need up to 38 litres of water every few days.
05:35But how to get it, when it's seemingly so hard to come by?
05:43Well, it has a neat trick.
05:47By eating at dawn when condensation is high, it can absorb most of its moisture from leaves.
06:03It also wastes no water sweating or panting.
06:07Instead, its temperature fluctuates with the surrounding air.
06:19But when beaten by the heat, giraffes must join their fellow beasts at the watering hole.
06:29Being tall, it's tricky.
06:35In this pose, the pressure is, quite literally, on.
06:48Pumping blood against gravity up to the head takes a powerful heart.
06:54It beats up to 170 times a minute.
06:57That's twice as fast as ours.
07:14This huge blood pressure, the highest of any mammal, should give a drinking giraffe a bad head rush.
07:25But instead, a clever system of valves regulates blood flow to the brain.
07:38The giraffe controls blood pressure so well that NASA has taken inspiration from these humble goliaths for the design of
07:47its spacesuits.
07:54It seems this big beast can even teach us a thing or two.
08:10The unique physical characteristics of a giraffe allow it to feed with relative ease.
08:18Many big beasts, though, have to fight for their food.
08:29This remote Indonesian island is home to an illustrious lizard.
08:44It owes its prehistoric good looks to its age.
08:48It's one of the few living species to have been around for over three million years.
09:04The Komodo dragon.
09:11Earth's largest lizard.
09:14Big enough to hog a king-size bear.
09:17And then some.
09:32Despite their intimidating credentials, these dragons don't have it easy.
09:39Around 6,000 remain, making them vulnerable to extinction.
09:50To add to their woes, these ferocious beasts have, for their size, a bite that is weaker than that of
09:58the average house cat.
10:05Their survival, though, relies on satisfying their insatiable hunger.
10:18These dragons have set their sights on this buffalo.
10:29At ten times a dragon's size, it's a very dangerous dinner option.
10:39One well-aimed kick, and a dragon could die hungry.
10:49So how does a Komodo, with its measly nip, take on such a formidable adversary?
10:56Its bite may be weak, but it's bolstered by around 60 backward-facing serrated teeth.
11:09The grip, and rip-bite.
11:23The grip, and rip-bite.
11:29On prey this size, it just draws a bit of blood.
11:35It's more deadly than it looks, though.
11:45The bite has set the dragon's next weapon in motion.
11:51Tucked either side of this lizard's weak jaw are venom glands.
12:00A bite releases the poison, preventing the prey's blood from clotting.
12:13Stage two takes days, and days, of patience.
12:29The buffalo's wound is not healing.
12:42Three weeks later, and it's finally time to eat.
12:55These ravenous reptiles can polish off 80% of their body weight in a single city.
13:10No energy gets wasted on chewing, either.
13:14A tube running from the base of the tongue to the lungs,
13:17means a dragon can breathe while it swallows each mouthful.
13:21In one.
13:32This combination of clever adaptations means this big beast can take down even bigger beasts
13:39to satisfy its need to eat, and ensure its survival.
13:54It's the most important thing to eat.
13:57It's the most important thing to eat.
13:58It's the most important thing to eat.
13:59It's the most important thing to eat.
13:59It's the most important thing to eat.
14:01Enormous appetites have led many sizeable species to target prey that should be out of their league.
14:10And the big bugs of the undergrowth are no exception.
14:17Imagine an insect that's big enough to take on a bird.
14:28Meet the Kalahari's armoured ground cricket.
14:40This hulk of the insect world puts its tiny European cousins to shame.
14:49As an omnivore, it eats plants, insects and crops.
14:53But there's one more thing it really needs.
15:02Red-billed Quilia follow the rain, gorging on crops that spring up in the now fertile ground.
15:20They're feeding not just themselves, but another million tiny mouths back at their nests.
15:30And that is precisely where these immense invertebrates are headed to.
15:42You see, life as a giant cricket is tough.
15:50Protein is crucial for these goliaths to sustain their huge frames.
15:59So they must seize any opportunity to eat meat.
16:19It's hard to slip under the radar though, when you're massive.
16:32So they've evolved some nifty defences.
16:42A spiny, beak-proof armoured shell protects its insides.
16:50And it can fire blood from pores in its exoskeleton.
17:02Temporarily blinding its assailant.
17:04Temporarily blinding its assailant.
17:08Temporarily blinding its assailant.
17:14With security out of the way, the meat feast is finally within reach.
17:20Work is feeling as tall as much as a young man.
17:22In it's large bones, it's hard to produce a quantic acid.
17:32It's kind of a little societal one.
17:35We're foods in pain to eat wirklich with смотрите.
17:35This big beast has evolved to use its brawn and its weapons to get the meal it needs to stay
17:41alive.
18:03the leaf litter is rife with oversized invertebrates with appetites to match
18:13the Kinabalu giant red leech would span the whole length of a grown man's thigh it maintains its
18:22full figure by eating its next-door neighbor the Bornean blue earthworm it's even bigger than the
18:34leech stretching to below a grown man's knee in this battle of the Titans though it's the smallest
18:48that wins the leech's muscular mouth crushes the worm taking the phrase down in one to the extreme
19:05New Zealand's carnivorous poelephanta is the sumo wrestler of the snail world the largest can grow
19:14to the size of a fist and that is just the shell
19:24their unfortunate prey is scraped into the gullet by a rasp like structure embellished with 6,000 teeth
19:44Japan's finger-length giant Hornet is one of the largest heaviest and deadliest insects in the world
19:54it feeds on the larvae of the humble honeybee to get to its meal it must fight its way into
20:04the hive
20:11a team of 30 can decimate a 30,000 strong hive in just three hours
20:19a time to figure out how to make the
20:49Beasts may have got their dining options sorted, but for some size poses another challenge
20:56when nature turns up the thermostat.
21:07The Australian outback.
21:08Temperatures here can hit 50 degrees Celsius.
21:22The red kangaroo is the world's largest marsupial.
21:34It can grow to a towering height of almost two metres.
21:41A single leap can cover seven metres, allowing them to hit a top speed of 35 miles per hour.
21:55But any exercise generates heat.
22:01Big bodies like these have comparatively small surface areas, making it hard for heat to escape.
22:11As the temperature soars, they head for shade.
22:27To cool their overheating bulk, they pace themselves in their own refreshing saliva.
22:37Their forearms are covered in a cobweb of capillaries.
22:41As the saliva evaporates, their blood cools.
22:47The blue parts of this thermal image are the coldest, showing just how effective their saliva bath can be.
23:05They also dig down beneath the scorching earth, to the cooler soil below, to sit out the worst of the
23:12day's heat.
23:18Sometimes the simplest solutions are the cleverest.
23:37In Australia's Northern Territory, a famously sun-averse mammal is also wrestling with the temperature.
23:48Staying cool just requires escaping the jaws of death.
24:05The little red flying fox is not so little.
24:14It's a species of megabat, with a body as big as a rat, and heavier, and a wingspan of a
24:27metre.
24:32If temperatures hit a tipping point of 40 degrees Celsius, hundreds of these big bats can die.
24:46It's 38 degrees, dangerously near the death zone.
24:53300,000 bats are dehydrating.
24:58Their burly bodies are producing more heat than make and release.
25:04What they really need is water.
25:16Skimming the river's surface with their chests is refreshing.
25:20But more importantly, it collects water in the hairs, to lick off back at the roost, and quench their thirst.
25:31But they're not the only ones making the most of the river.
25:43This is the Australian freshwater crocodile, or fresh sheep to the locals.
25:53The sun makes these cold-blooded reptiles alert and ready to hunt.
26:18This deadly game of tag is non-negotiable.
26:23If they don't risk becoming fodder for a fresh sheep, they'll die in the heat.
26:43Fortune favours these brave bats.
26:48Most of the time.
27:04So being big is not so great when it's hot.
27:10But can a bulky frame help stave off the cold?
27:17Well, if you're warm-blooded, the answer is yes.
27:23Mammals tend to be beefier in cooler climes.
27:29Take the biggest bear on earth, the polar bear.
27:35Its huge volume stores the heat in temperatures as low as minus 37 degrees Celsius.
27:44And their 10-centimetre blubber layer is such an effective insulator,
27:49these mighty mammals sometimes need a good rub in the snow to cool down.
28:02But if you're cold-blooded, you rely on a daily dose of sun to warm up your insides.
28:09So reptiles and insects generally fare better in the cold when they're small.
28:17Some species, though, just can't help but defy convention.
28:24Remember the gargantuan bird-eating cricket of the Kalahari?
28:29Well, it has a distant cousin that beats it hands down in the size stakes.
28:38This colossal beast is the mountain stone wetter.
28:44An insect that's grown as big as a mouse.
28:48For one simple reason.
28:54Wetters evolved back when there were no native mammals.
28:58So they took the ecological niche normally reserved for small rodents
29:02and matched them for size.
29:10Being a massive insect is fine when it's warm.
29:14But this monster species lives high in New Zealand's southern alps.
29:31It had to evolve a way to survive being big in the cold.
29:37By doing something no other insect this large can.
29:46Even in the shelter of a cave, it can be below zero.
29:51When ice sets in around it, this ingenious hulk of an insect does something very strange indeed.
30:00It freezes itself to death, nearly.
30:14This wetter species actually encourages ice to form in its body.
30:22Ice crystals are sharp.
30:24If they form inside a cell, they'd tear through the membrane like razor blades in a balloon.
30:34So the key to survival is to ensure ice only forms outside its cells.
30:43First, the wetter dehydrates the cells, drawing water out.
30:49There, the combination of water and special proteins trigger the formation of ice crystals.
31:06In this state of suspended animation, a mountain stone wetter can survive temperatures as low as minus ten degrees Celsius.
31:19An extraordinary 80% of its body can be frozen solid.
31:34When temperatures rise and the ice thaws, a wetter can gradually re-enter the land of the living.
32:03Having got their temperature under control, our big beasts can go about their day.
32:09But the simple act of moving can be challenging in itself.
32:18Generally, the bigger the beast, the more it weighs.
32:25And the heavier the beast, the harder it finds lifting its weight against the downward pull of gravity.
32:39Take Earth's largest land animal, the six-ton African elephant.
32:48Tracking down food in the Namibian desert can mean lugging its eye-watering load for 25 miles a day.
33:02Two-thirds of an elephant's weight is channelled through its front legs.
33:13The solution? Fatty pads in its dustbin-sized feet to absorb the shock.
33:24With each step, they spread the load, protecting the skeleton from the impact of its monumental weight.
33:37Even with the health of ingenious evolutionary adaptations, though, the fact remains that gravity limits how big a land animal
33:46can get.
33:55So how do big beasts fare...
34:03...beneath the waves?
34:10Down here, water's buoyancy helps support nature's heavyweights.
34:21Which is why this is the domain of the most enormous animal ever to have existed.
34:32The 150-ton blue whale outdoes even the biggest dinosaurs for size.
34:43Its tongue alone weighs as much as its largest land rival, the elephant.
34:52Its heart is almost as big as a golf buggy.
34:58Its major artery is as wide as a human head.
35:04And it's thought they're still growing.
35:10As long as the blue whale has enough food, this species may just keep on getting bigger.
35:21Despite its eye-popping stats, the blue whale can move with ease.
35:31Which is more than can be said for excessively heavy beasts that want to get airborne.
35:43Some birds have found benefits to growing big.
35:47But in the process, they've lost the ability to fly.
35:55Take the kakapo, the world's heaviest parrot.
36:08To reach the fruit and leaves that maintain its full figure, it has no choice but to climb.
36:21The ostrich has a similar problem.
36:27It's the largest living bird, nearly three metres tall.
36:32With a vast two metre wingspan that is useless for flying.
36:39Instead, it's perfected the art of running away from predators.
36:49With a top speed of over 40 miles per hour, it's the fastest two-legged animal on earth.
36:55It could complete a marathon in 45 minutes.
37:10Being big, though, doesn't have to make air travel impossible.
37:18Over 65 million years ago, a beast far larger and heavier than an ostrich proudly displayed its aerial skills in
37:26the skies above what is now Europe.
37:35Hats-a-got-tricks may well be the largest flying animal ever known.
37:49If it were alive today, it would be tall enough to peer into a first-floor window.
37:59And they could take off from a standing start, owing to the sheer power of their wing muscles.
38:10Despite their impressive aerial antics, it seems they didn't hunt on the wing, but fed on the ground.
38:19Supporting their great weight with extra feet on each wing.
38:39Back in the 21st century, the bird that comes closest to a Hatsi is the albatross.
38:55At 3.5 metres, the wandering albatross has the longest wingspan of any bird alive today.
39:08And an albatross can do something Hatsi apparently couldn't.
39:14Hunt from the air.
39:15Hunt from the air.
39:18These big birds spend most of their lives at sea, scouring the ocean's surface for food.
39:26Hunt from the air.
39:40They only come into land to breed.
39:48this royal albatross has made a pit stop on New Zealand's South Island where her
39:54two-month-old chick is waiting for food
40:08this big baby can polish off half a kilo of fish in a single sitting
40:19to find its next meal mum will have to scour a mere 600 miles of ocean
40:29so given she weighs as much as a small dog how does she manage to fly
40:39her enormous wings get her big body airborne the secret to the albatross staying up there though
40:47is in its nostrils
40:54special sensory organs measure the speed of the surrounding air what they're searching for are
41:01changes in airspeed but the water's surface the air is almost still slowed as it hits the waves
41:1710 meters up it's windy as an albatross climbs into the faster air it gets free lift then turning
41:30sharply it plunges down into the slower air gravity has helped it accelerate to over 70 miles per hour
41:56downward momentum catapults it back up again like a roller coaster into the lift of the faster air
42:06it's called dynamic soaring and crucially it means they can fly without flapping their wings
42:25by exploiting the energy of the wind they expend almost none of their own
42:33this aerial efficiency is what makes such a big body capable of flying non-stop for over 10,000 miles
42:41without the need to set foot on dry land for years at a time
42:56for a mother though it's straight back to the nest to satisfy the big appetite of her chunky chick
43:14the demands of rearing massive offspring is something many a big beast can appreciate
43:24the challenges often begin at birth
43:38because of her size a hippo keeps cooling water
43:43it's here that she'll usually deliver her 45 kilo meter long baby
43:54which leaves her with a problem
44:00her little one can't breathe underwater
44:03giving mum just 40 seconds to get her newborn to the surface for its first gulp of air
44:25elephant babies spend nearly two years in the womb to reach their record-breaking 100 kilo birth weight
44:36they take so long to grow that mum has to nurse them for up to four years
44:54for some big beasts though the trials of the mating game begin long before the birth
45:08it's the breeding season on the beaches of northern Patagonia
45:18over 15,000 female southern elephant seals have flocked here to find themselves a truly massive mate
45:34a bull seal can be a staggering eight times his suitors size
45:41he can weigh as much as six dairy cows
45:53and yet she's not the one in danger of getting injured in this game
45:58he is
46:00to secure his legacy
46:02a male must mate with as many lucky ladies as possible
46:14these females are all under the watchful eye of one bull
46:23he's the beach master of a harem that can number 150
46:31to protect his exclusive mating rights he has to stay on his beach territory 24 7 without food or drink
46:40for three months
46:45luckily for him he's really fat
46:49his 15 centimeter blubber born of a diet of just seafood provides him with energy and water
47:03for an extra boost while napping he holds his breath for minutes at a time
47:09every ounce of energy must be saved
47:21competitors are always nearby
47:30so
47:37so
47:38so
47:39so
47:55it's a battle of bulk
47:57and team
47:59so
48:09his fat suit can't protect him from his rivals eight centimeter canines
48:15so
48:34but even after months of fasting the beach master defeats his challenger
48:55his
48:56prize
48:56to father most of the pups this season
49:04for the loser
49:05it's game over
49:06three quarters of bulls each year
49:09three quarters of bulls each year
49:10never get to mate
49:16it's the bigger the better
49:17in the elephant seal mating game
49:35the next generation is a risky business
49:38not just for males
49:40one beast
49:42one beast has grown so big
49:43that having babies means gambling with her life
49:54the humble hermit crab
49:56harmless
49:58and traditionally small
50:04except for this member of the family
50:11the
50:11the coconut crab
50:12or robber crab
50:15the largest land crab on earth
50:21the
50:21the south pacific islands of vanuatu
50:24are pretty hard to reach
50:29so
50:29having the place mostly to themselves
50:31it seems these critters
50:33have taken the opportunity to grow as big as medium sized mammals
50:39their legs can span a meter
50:43and they're strong enough to lift the equivalent
50:46of ten house bricks
50:51being big has allowed them to cultivate
50:54some rare talents
51:01true to their name they can crack a coconut
51:07and they'd be known to kill and eat rats
51:13but there's one thing these crabs simply can't do
51:17and that
51:18is swim
51:26this crab lives its adult life
51:28entirely on land
51:30so you'd think this wouldn't be too much of a problem
51:33and for most of their days
51:35it isn't
51:43but once a year
51:44the females of these colossal crustaceans
51:47have no choice
51:48but to brave the waves
51:50in order to pass on their genes
52:11this female has been nursing her fertilized eggs on her abdomen
52:15having mated some weeks ago
52:18but tonight's the night
52:20to release her precious cargo
52:29and like all crabs
52:31that's done in water
52:40she must tread carefully
52:43she's so well adapted to land
52:45that she's evolved a form of lung
52:47that can no longer breathe underwater
52:52and her great weight
52:53means if she gets out of her depth
52:56she'll sink
52:57and drown
53:04clinging for life
53:05she releases her eggs into the waves
53:16they'll hatch into swimming larvae
53:24but in a month's time
53:26they'll be back on land
53:31there they too
53:33will grow into terrestrial giants
53:52across the coral sea
53:54from the coconut crab's paradise isle
53:56is an immense sea beast
53:58that also reproduces
54:00just once a year
54:04when it does
54:05it gets even bigger
54:12this springtime full moon
54:15is the trigger
54:16for a submarine spectacular
54:20when the perfect tide height
54:22day length
54:23and sea temperature all align
54:25this happens
54:27this happens
54:36400 species of coral
54:38across 3,000 reefs
54:41reproduce over a series of nights
54:44the animals
54:50tucked inside their limestone armor
54:53millions of coral polyps
54:56release their eggs and sperm
54:58simultaneously
55:05you may be wondering what's big
55:07about these tiny floating jewels
55:09well together
55:11they're responsible for growing
55:13the world's largest single living structure
55:17the great barrier reef
55:30at 1400 miles long
55:32it's over twice the length
55:34of great britain
55:37making it the only living thing
55:39visible from space
55:45each time
55:46each time the reef reproduces
55:48its gigantic scale increases
55:56the resulting coral larvae
55:58travel back down to make their home
56:00on the reef
56:07this monumental structure
56:10once grew
56:11by several centimeters each year
56:20of course
56:21there's a twist to this tale
56:29in recent years
56:30it's thought that half the coral
56:32in this big beast
56:33has died
56:37it's believed
56:38it's believed rising sea temperatures
56:39are responsible
56:40for driving away the colorful algae
56:42that live inside coral
56:45without nutrients
56:47and its distinctive hues
56:48it's left bleached white
56:55it appears our modern world
56:57is taking its toll
56:59on this great beast
57:09we may not be amongst nature's biggest beasts
57:12but we do so often have the biggest impact
57:15on our planet
57:16and on the animals we share it with
57:22our fascination with the goliaths of our world
57:24can prove catastrophic for them
57:31and nature's giants can't survive
57:34without ample space to roam
57:36plenty to eat
57:37and prime habitat
57:47half the remarkable titans featured here
57:50are threatened with extinction
57:59when you consider the astonishing solutions
58:02nature's biggest beasts have come up with
58:04to life's big problems
58:13ingenious ways to find food
58:15to keep warm or stay cool
58:17to move around
58:18and to reproduce
58:23we should not only celebrate their success
58:26but also do what we can
58:27to ensure they stick around
58:30for generations to come
58:43monkeys protecting babies from a crocodile weighing a ton
58:47stunning locations with vast flooded forests
58:50borneo earth's tropical islands in half an hour
58:53don't tell me
58:54don't tell me
58:55it's next
58:56you
58:57you
59:08you
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