0:00:04 > 0:00:06Planet Earth.
0:00:06 > 0:00:09Millions of different species.
0:00:11 > 0:00:13But a few are special.
0:00:17 > 0:00:18Thriving.
0:00:20 > 0:00:21Dominating.
0:00:26 > 0:00:28These are the opportunists...
0:00:32 > 0:00:34..the collaborators...
0:00:36 > 0:00:37..the survivors.
0:00:40 > 0:00:43What makes these animals so successful?
0:00:45 > 0:00:48By delving deep beneath the skin,
0:00:48 > 0:00:52we'll reveal the unique features that set some species apart.
0:00:59 > 0:01:02In this series, new behaviour
0:01:02 > 0:01:05and the very latest scientific research
0:01:05 > 0:01:09will throw fresh insight into the wonder of animals.
0:01:26 > 0:01:27At first sight,
0:01:27 > 0:01:31penguins seem ill-suited to their environment.
0:01:33 > 0:01:36But this humble bird
0:01:36 > 0:01:40has actually conquered an extraordinary range of habitats.
0:01:42 > 0:01:43From deep forests...
0:01:51 > 0:01:52..to tropical waters.
0:01:59 > 0:02:00Bustling cities...
0:02:03 > 0:02:04..to busy beaches.
0:02:11 > 0:02:17And most impressive of all, the toughest place on the planet.
0:02:19 > 0:02:20Antarctica.
0:02:20 > 0:02:23Where they not only survive,
0:02:23 > 0:02:25they thrive.
0:02:42 > 0:02:47So exactly what is the secret to their success?
0:03:00 > 0:03:03Now penguins have a unique body shape.
0:03:06 > 0:03:10A rotund abdomen, stubby little legs
0:03:10 > 0:03:14and stiff wings may not seem like the perfect recipe
0:03:14 > 0:03:16but I've got to tell you that sometimes
0:03:16 > 0:03:18appearances can be deceptive.
0:03:20 > 0:03:22These very characteristics
0:03:22 > 0:03:25are central to the penguin's success,
0:03:25 > 0:03:27starting with those legs.
0:03:35 > 0:03:37These are Chinstraps.
0:03:42 > 0:03:44Residents of Deception Island
0:03:46 > 0:03:47in Antarctica.
0:03:49 > 0:03:55After spending the day 60km out at sea hunting krill,
0:03:55 > 0:03:59they now need to get the much-needed food back to their chicks.
0:04:00 > 0:04:05Like all penguins, they spend a lot of time at sea
0:04:05 > 0:04:09but surprisingly half of their time is spent on land.
0:04:11 > 0:04:16So their bodies have to operate effectively in both environments.
0:04:19 > 0:04:23Their short legs, positioned right at the end of their bodies,
0:04:23 > 0:04:26seem to work against them,
0:04:26 > 0:04:27forcing them to waddle.
0:04:36 > 0:04:39For every penguin species,
0:04:39 > 0:04:45this bizarre rocking motion is the only way they can walk,
0:04:45 > 0:04:48but it actually works in their favour.
0:04:52 > 0:04:59Like a pendulum, the motion stores energy at the end of each swing,
0:04:59 > 0:05:02energy that can be spent in the next step.
0:05:06 > 0:05:11The percentage of energy retained is known as the recovery rate.
0:05:13 > 0:05:17Humans have a recovery rate of about 65%,
0:05:17 > 0:05:22in penguins however, this can be up to 80%.
0:05:28 > 0:05:32But for our Chinstraps, walking is only half the challenge.
0:05:35 > 0:05:40Their nesting site is 160 metres high above them,
0:05:42 > 0:05:45on the rim of a volcano.
0:05:48 > 0:05:50It's a near-vertical climb.
0:05:56 > 0:06:00Compounded by wet and slippery volcanic ash.
0:06:13 > 0:06:18The Chinstraps' feet may be short, but they're also very strong
0:06:18 > 0:06:20and they're armed with sharp claws.
0:06:21 > 0:06:23Their anatomy wins over.
0:06:30 > 0:06:34Against the odds, penguins' legs work well on land.
0:06:38 > 0:06:43But it's beneath the waves where they really come into their own.
0:06:46 > 0:06:51They can swim faster and deeper than any other bird...
0:06:55 > 0:06:59..accelerating to 15mph in less than a second...
0:07:02 > 0:07:06..and reaching depths of up to 500 metres.
0:07:10 > 0:07:12The position of their legs is vital.
0:07:16 > 0:07:18Most other swimming birds
0:07:18 > 0:07:21use their legs to propel them through the water.
0:07:22 > 0:07:25But, sticking out of the middle of their bodies
0:07:25 > 0:07:28these legs cause unwanted drag.
0:07:36 > 0:07:40Penguins, on the other hand, are different.
0:07:41 > 0:07:47Their feet and legs are tucked away at the very end of their bodies
0:07:47 > 0:07:49minimising drag significantly.
0:07:52 > 0:07:56In this position, they act as an effective rudder system.
0:07:58 > 0:08:03Controlling both lateral and vertical motion.
0:08:03 > 0:08:08This enables these birds to make a perfect 180 degree turn
0:08:08 > 0:08:11in as little as a fifth of a second.
0:08:19 > 0:08:25So penguins' legs can allow them to climb volcanoes
0:08:25 > 0:08:27and manoeuvre through water with ease.
0:08:30 > 0:08:32But where does their power come from?
0:08:34 > 0:08:38Well, it's all in the wings.
0:08:39 > 0:08:40For most birds,
0:08:40 > 0:08:43wings are highly specialised pieces of apparatus
0:08:43 > 0:08:45that have evolved to allow them to fly.
0:08:45 > 0:08:47And if we look at this pheasant skeleton
0:08:47 > 0:08:50you can see that the main joints in the wing,
0:08:50 > 0:08:53here at the shoulder, the elbow and the wrist
0:08:53 > 0:08:56are shaped to allow it to flex, to flap
0:08:56 > 0:08:59so the bird can eventually get into the air.
0:08:59 > 0:09:03Penguins, on the other hand, lost the ability to fly
0:09:03 > 0:09:04some 60 million years ago
0:09:04 > 0:09:07and two of the joints in their wing,
0:09:07 > 0:09:10here at the elbow and the wrist have fused.
0:09:10 > 0:09:14In fact, these days the wing can only move at the shoulder
0:09:14 > 0:09:19and it's this that gives penguins their characteristic posture.
0:09:22 > 0:09:24And although a hindrance on land,
0:09:24 > 0:09:28they are fundamental for underwater propulsion.
0:09:39 > 0:09:42The fused joints and rigid flattened bones
0:09:42 > 0:09:44create the perfect paddle.
0:09:45 > 0:09:48Faultlessly adapted for "flying"
0:09:48 > 0:09:50through the water.
0:10:13 > 0:10:17A penguin's wings and legs may appear cumbersome,
0:10:17 > 0:10:21but, when combined with a torpedo-shaped body,
0:10:21 > 0:10:24adapted to glide through water,
0:10:24 > 0:10:28these birds make the most exquisite swimmers.
0:10:40 > 0:10:45It's a body plan that has enabled around 17 species to thrive,
0:10:45 > 0:10:47right across the southern hemisphere.
0:10:49 > 0:10:54They occur wherever nutrient-rich cold waters are found,
0:10:54 > 0:10:58but can also be seen as far north as the equator
0:10:58 > 0:11:016,000 miles from the South Pole.
0:11:07 > 0:11:08The seas here in the Galapagos
0:11:08 > 0:11:13are refrigerated by currents flowing all the way from Antarctica.
0:11:16 > 0:11:19The warmer waters of the equator create a thermal barrier...
0:11:21 > 0:11:25..preventing the penguins from conquering the northern hemisphere.
0:11:25 > 0:11:28In those tropical conditions,
0:11:28 > 0:11:30their rounded, blubber-filled bodies
0:11:30 > 0:11:32would simply overheat.
0:11:39 > 0:11:42But it's exactly this body shape
0:11:42 > 0:11:46that allows penguins to survive year round
0:11:46 > 0:11:49in a place that no other animal can.
0:11:54 > 0:11:55Antarctica.
0:11:57 > 0:11:59Dark,
0:11:59 > 0:12:03barren
0:12:03 > 0:12:06and locked in ice for much of the year.
0:12:06 > 0:12:09This is a desert like no other.
0:12:12 > 0:12:15It's the coldest,
0:12:15 > 0:12:18windiest,
0:12:18 > 0:12:20driest continent on earth.
0:12:24 > 0:12:28It's hardly rained or even snowed for two million years.
0:12:31 > 0:12:35And yet, against the odds,
0:12:35 > 0:12:39six penguin species call this place home.
0:12:41 > 0:12:46And they all follow a similar, rounded body shape.
0:12:46 > 0:12:49Consisting of up to 30% blubber.
0:13:05 > 0:13:08But there's more to a penguin's cold-conquering anatomy
0:13:08 > 0:13:10than just fat.
0:13:11 > 0:13:17Beneath this rotund exterior, lies a complex system of mechanics.
0:13:22 > 0:13:27In the chill of Antarctica, the extremities are most at risk.
0:13:32 > 0:13:36Feet and wings are inevitably going to get cold,
0:13:36 > 0:13:39but it's vital for the penguin's survival
0:13:39 > 0:13:41that they can operate at any temperature.
0:13:50 > 0:13:53To work effectively, muscles require heat.
0:13:55 > 0:14:01So, instead of housing them in their exposed limbs
0:14:01 > 0:14:06a penguin hides these muscles deep inside its insulated body.
0:14:12 > 0:14:16Here, these warm muscles connect to tendons,
0:14:16 > 0:14:18which are much less susceptible to cold.
0:14:22 > 0:14:25And it's these tendons that then connect to the bones
0:14:25 > 0:14:27within the feet and wings.
0:14:33 > 0:14:36Working like a remote operation by wire,
0:14:36 > 0:14:40the penguin has complete control over their essential limbs
0:14:40 > 0:14:43even in the coldest conditions on the planet.
0:14:46 > 0:14:49But to keep this muscular powerhouse warm,
0:14:49 > 0:14:52their bodies need some serious insulation.
0:15:04 > 0:15:07Penguins may not be able to fly,
0:15:07 > 0:15:11but they have more feathers than any other bird.
0:15:13 > 0:15:18In fact up to three times the amount, densely packed together.
0:15:19 > 0:15:23The small, stiff feathers overlap so tightly,
0:15:23 > 0:15:26they form a protective seal,
0:15:27 > 0:15:29trapping a blanket of still air
0:15:29 > 0:15:33between the skin and a fluffy feather outgrowth.
0:15:34 > 0:15:38It's a highly sophisticated form of insulation.
0:15:40 > 0:15:44And yet, these same feathers have a very different purpose too.
0:15:47 > 0:15:51Here in South Africa, extreme cold is no longer an issue.
0:15:57 > 0:16:03For African penguins, their feathers hold the key to cooling off
0:16:03 > 0:16:04as well as warming up.
0:16:08 > 0:16:13The secret is a muscle attached to the base of each and every feather...
0:16:17 > 0:16:21..which opens up the densely packed layers
0:16:21 > 0:16:24allowing heat to escape from the swollen blood vessels.
0:16:26 > 0:16:30Penguin feathers offer complete climate control
0:16:30 > 0:16:33in both hot and cold weather.
0:16:34 > 0:16:40And it's so effective, they can even trick state-of-the-art technology.
0:16:45 > 0:16:48When scientists from Glasgow University
0:16:48 > 0:16:52recently studied Emperor penguins using a thermal imaging camera,
0:16:52 > 0:16:54something didn't quite add up.
0:16:57 > 0:17:01As warm-blooded animals in a freezing environment,
0:17:01 > 0:17:05they expected the birds to register hotter than their surroundings.
0:17:08 > 0:17:12But they actually clocked in at five degrees cooler.
0:17:16 > 0:17:18The very outer feather layers
0:17:18 > 0:17:22are losing a lot of heat to the clear sky above them,
0:17:22 > 0:17:25which makes the penguin's exterior edge appear colder
0:17:25 > 0:17:27than the surrounding air.
0:17:28 > 0:17:30You would expect this to be a problem
0:17:30 > 0:17:35but as we've seen, penguin plumage is special.
0:17:36 > 0:17:39In fact, the interlocking, densely packed feathers
0:17:39 > 0:17:42create such a strong barrier,
0:17:42 > 0:17:45that although the temperature of the outer layer
0:17:45 > 0:17:48was measured at minus 23 degrees centigrade,
0:17:48 > 0:17:54the penguin's actual body temperature was up to 60 degrees hotter.
0:17:57 > 0:18:00Despite a thick layer of blubber,
0:18:00 > 0:18:04more than 80% of a penguin's insulation
0:18:04 > 0:18:06is down to their incredible feathers.
0:18:10 > 0:18:11And they need it.
0:18:22 > 0:18:25When the polar winter draws in,
0:18:25 > 0:18:27it gets darker
0:18:27 > 0:18:30and much, much colder.
0:18:33 > 0:18:35With the wind chill, temperatures can drop
0:18:35 > 0:18:39to an astonishing minus 70 degrees centigrade.
0:18:41 > 0:18:45But the Emperor penguin is the ultimate specialist
0:18:45 > 0:18:47in extreme survival.
0:18:49 > 0:18:54Its anatomy allows it to face an astonishing challenge.
0:19:01 > 0:19:04It doesn't just survive the winter,
0:19:06 > 0:19:09it's the only animal to breed here in the winter.
0:19:11 > 0:19:14Enduring these conditions makes sense,
0:19:14 > 0:19:17it means their chicks will fledge at the right time in spring
0:19:17 > 0:19:21when the seas are at their richest.
0:19:21 > 0:19:27To achieve this, the males must spend up to 120 days without food,
0:19:27 > 0:19:32each incubating a single egg in the middle of the Antarctic winter.
0:19:36 > 0:19:40Meanwhile the females are nearly 100km away,
0:19:40 > 0:19:42fishing on the edge of the ice sheet.
0:19:45 > 0:19:47For the males left behind,
0:19:47 > 0:19:51feathers, blubber and hidden muscles simply aren't enough.
0:19:55 > 0:19:59It's long been known that the males shuffle into "huddles"
0:19:59 > 0:20:02with their eggs safely stored on top of their feet.
0:20:08 > 0:20:11Sometimes these groups reach into the thousands.
0:20:12 > 0:20:15Strength in numbers against the bitter cold.
0:20:18 > 0:20:19It is effective.
0:20:20 > 0:20:22Temperatures can vary dramatically
0:20:22 > 0:20:25depending on a penguin's location in the huddle.
0:20:27 > 0:20:32Scientists have measured as high as 37 degrees centigrade
0:20:32 > 0:20:33in the heart of the group,
0:20:33 > 0:20:38which is up to 80 degrees hotter than on the outer edge.
0:20:40 > 0:20:41It had been thought
0:20:41 > 0:20:45that the penguins kept warm with all of this huddling tightly together.
0:20:46 > 0:20:52A recent discovery, however, has turned that theory on its head.
0:20:52 > 0:20:56Instead of squashing into one another's plumage,
0:20:56 > 0:21:00these penguins are barely touching.
0:21:08 > 0:21:13This prevents the feathers from being compressed,
0:21:13 > 0:21:17which would compromise their powers of insulation.
0:21:24 > 0:21:29So keen are they to protect this treasured outer layer,
0:21:29 > 0:21:33that an individual penguin only needs to move two centimetres
0:21:33 > 0:21:36for its neighbour to react,
0:21:36 > 0:21:40also performing a two centimetre step in the same direction.
0:21:44 > 0:21:47Just one penguin's movement
0:21:47 > 0:21:50creates a chain reaction throughout the huddle.
0:21:51 > 0:21:52Like a Mexican wave.
0:21:55 > 0:21:57Prior to this study,
0:21:57 > 0:22:01it was believed that these waves were caused by cold penguins
0:22:01 > 0:22:03pushing in to the warmer centre,
0:22:03 > 0:22:08but now we know they can originate from any bird
0:22:08 > 0:22:10in any position within the huddle.
0:22:15 > 0:22:20It could even be started by a warm bird in the centre
0:22:20 > 0:22:22travelling outwards to cool down.
0:22:31 > 0:22:36As the sun returns, so do the females.
0:22:38 > 0:22:40Allowing the males to head out to sea.
0:22:43 > 0:22:46Now they can feed and build up enough fat reserves
0:22:46 > 0:22:48for another gruelling breeding season.
0:22:52 > 0:22:57It's here that another fantastic feathery adaptation comes into play.
0:23:03 > 0:23:07The Emperor is the largest species of penguin.
0:23:07 > 0:23:10Weighing in at up to 38kg,
0:23:10 > 0:23:12a third of which is blubber.
0:23:14 > 0:23:16The more body fat,
0:23:16 > 0:23:19the more likely they are to survive the coming winter.
0:23:29 > 0:23:31But to maintain it,
0:23:31 > 0:23:32they need to hunt.
0:23:34 > 0:23:38Diving longer and deeper than any other penguin.
0:23:39 > 0:23:44They hold their breath for up to 20 minutes at a time
0:23:44 > 0:23:48to maximise their chance of finding food
0:23:48 > 0:23:51and building up their vital fat stores.
0:23:54 > 0:24:00But all that bulk comes at a price and poses an interesting problem.
0:24:04 > 0:24:08How does a bird the same weight as a baby hippo
0:24:08 > 0:24:11get itself back out of the water?
0:24:17 > 0:24:22A recent, revelatory study suggests an intriguing solution.
0:24:27 > 0:24:29A team of European scientists
0:24:29 > 0:24:32recently looked again in more detail
0:24:32 > 0:24:35at some long-observed penguin behaviour.
0:24:36 > 0:24:38At the end of a long dive,
0:24:38 > 0:24:41instead of jumping straight out of the water,
0:24:41 > 0:24:46many Emperors surface for a short time and then dive back down again.
0:24:49 > 0:24:53Only then do they shoot back up to the surface,
0:24:53 > 0:24:56this time accelerating clear of the water.
0:25:03 > 0:25:06So why do they have this temporary pit stop?
0:25:10 > 0:25:14The obvious answer is that they return for a much needed gulp of air
0:25:14 > 0:25:16and a bit of rest...
0:25:22 > 0:25:26..before diving back down to pick up enough speed for their grand exit.
0:25:31 > 0:25:34But what the research team now think is going on,
0:25:34 > 0:25:36is actually a lot more interesting.
0:25:44 > 0:25:48When the birds come to the surface, they appear to preen.
0:25:50 > 0:25:54In fact they're actively collecting air
0:25:54 > 0:25:57within a fine, downy mesh at the base of their feathers.
0:25:59 > 0:26:03As the penguins descend, the water pressure increases,
0:26:03 > 0:26:08reducing the volume of the trapped air by up to 75%.
0:26:10 > 0:26:14The birds again rely on their individual muscles
0:26:14 > 0:26:15at the base of each feather.
0:26:17 > 0:26:19This time, they clamp them shut,
0:26:19 > 0:26:23locking in the compacted air that they've collected.
0:26:26 > 0:26:30When it's time to exit, the penguin then swims upwards,
0:26:30 > 0:26:31as fast as it can.
0:26:32 > 0:26:34The trapped air in the plumage
0:26:34 > 0:26:38expands during their ascent and pours through the feathers
0:26:38 > 0:26:43producing the bubbly wakes we can see behind them.
0:26:43 > 0:26:47The tiny micro bubbles form a lubricating coat of air
0:26:47 > 0:26:49that surrounds the penguin.
0:26:51 > 0:26:55This drastically reduces drag
0:26:55 > 0:27:00and allows them to accelerate to twice their normal swimming speed
0:27:00 > 0:27:02at the point they leave the water.
0:27:12 > 0:27:14This flightless bird...
0:27:16 > 0:27:18..finally becomes airborne.
0:27:44 > 0:27:49Penguins possess a truly extraordinary anatomy,
0:27:49 > 0:27:53perfectly adapted to thrive in some extreme environments.
0:28:00 > 0:28:02Their feet reduce drag underwater
0:28:02 > 0:28:05and even allow them to climb volcanoes.
0:28:09 > 0:28:13Their wings are perfect for flying beneath the waves.
0:28:17 > 0:28:18And their rotund body
0:28:18 > 0:28:23is packed full of hidden mechanics and covered with feathers
0:28:23 > 0:28:25which keep them cool and warm.
0:28:30 > 0:28:34And even allow them to propel themselves out of the water.
0:28:36 > 0:28:38Thanks to their unique body plan,
0:28:38 > 0:28:41they're not just one of the great survivors
0:28:41 > 0:28:45they are one of the most successful animals on earth.
0:28:52 > 0:28:55And that is the wonder of penguins.