0:00:02 > 0:00:06The natural world is full of extraordinary animals with
0:00:06 > 0:00:09amazing life histories.
0:00:09 > 0:00:12Yet certain stories are more intriguing than most.
0:00:15 > 0:00:19The mysteries of a butterfly's lifecycle,
0:00:19 > 0:00:23or the strange biology of the Emperor penguin,
0:00:23 > 0:00:26some of these creatures were surrounded by myth
0:00:26 > 0:00:30and misunderstandings for a very long time.
0:00:30 > 0:00:34And some have only recently revealed their secrets.
0:00:34 > 0:00:38These are the animals that stand out from the crowd.
0:00:38 > 0:00:42The curiosities I find most fascinating of all.
0:00:51 > 0:00:56The bodies of some animals stretch and shrink in extraordinary ways.
0:00:57 > 0:01:02Constrictor snakes can swallow prey twice their own size.
0:01:02 > 0:01:06While the camel's hump can almost double in weight,
0:01:06 > 0:01:10giving it the energy to travel huge distances across deserts.
0:01:10 > 0:01:15What is the secret behind such expandable bodies?
0:01:20 > 0:01:24Also in this programme, we meet two animals whose extraordinary
0:01:24 > 0:01:27body shapes are determined by their diet.
0:01:27 > 0:01:29The blue whale grows enormous
0:01:29 > 0:01:33by feeding on tiny shrimp-like creatures,
0:01:33 > 0:01:38while flamingos spend their lives eating with their heads upside down.
0:01:38 > 0:01:42And yet, both ways are curiously similar.
0:01:50 > 0:01:54We've long been fascinated by the camel's ability to live in the
0:01:54 > 0:01:59harshest of deserts, places where during summer temperatures
0:01:59 > 0:02:02can soar up to 50 degrees Celsius.
0:02:02 > 0:02:07While in winter, they can drop to 30 degrees below freezing.
0:02:09 > 0:02:12With little in the way of food or water,
0:02:12 > 0:02:17camels can sometimes go without eating or drinking for over a week.
0:02:18 > 0:02:22Most other animals couldn't survive conditions like this.
0:02:22 > 0:02:25How does the camel do it?
0:02:28 > 0:02:32The camel's secret was thought to lie in its hump.
0:02:32 > 0:02:36In a healthy camel, it can be big and firm, like this one, and
0:02:36 > 0:02:40weigh as much as 30 kilos, which is the weight of a ten-year-old child.
0:02:40 > 0:02:44But if the camel goes without food, and particularly water,
0:02:44 > 0:02:48for any length of time, then the hump can get floppy
0:02:48 > 0:02:53and even droop over on one side, as that one has done.
0:02:53 > 0:02:58So, people used to think that the camel stored water in its hump.
0:03:02 > 0:03:07In fact, there are two different kinds of camel - the one hump,
0:03:07 > 0:03:12or dromedary, and the two-humped, or the bactrian.
0:03:12 > 0:03:15Nearly all camels alive today are the domesticated
0:03:15 > 0:03:17descendants of one or the other.
0:03:21 > 0:03:26The wild dromedary almost certainly doesn't exist.
0:03:26 > 0:03:28And only a few bactrian camels remain,
0:03:28 > 0:03:31roaming the deserts of central Asia.
0:03:31 > 0:03:36The camel is a very tough animal, but in the wild today,
0:03:36 > 0:03:38it's rarer than the giant panda.
0:03:41 > 0:03:45It's hard to say where the idea of a water storing hump came from.
0:03:45 > 0:03:49The Ancient Romans were the first to suggest that the
0:03:49 > 0:03:52camel may have in a built-in water reservoir.
0:03:52 > 0:03:57And then, later on, people got the idea that it had two stomachs -
0:03:57 > 0:03:59one for food and one for water.
0:04:01 > 0:04:06In the 18th century, an eminent anatomist, John Hunter, decided to
0:04:06 > 0:04:09investigate the truth behind these assertions,
0:04:09 > 0:04:11and he dissected a camel.
0:04:11 > 0:04:15He found that the stomach consisted of three or four compartments,
0:04:15 > 0:04:18similar to those of a cow or a sheep.
0:04:18 > 0:04:22But inside one of those compartments, he discovered these
0:04:22 > 0:04:27pocket-like structures, which are not found in any other large mammal.
0:04:27 > 0:04:31Hunter didn't know what the pockets were for, but others after him
0:04:31 > 0:04:35proposed that they were special water storage cells.
0:04:35 > 0:04:39And then, despite any kind of evidence to prove that this
0:04:39 > 0:04:44was true, for another 250 years, books on natural history,
0:04:44 > 0:04:48like this one, featured illustrations of water
0:04:48 > 0:04:50storage cells in the camel's stomach.
0:04:52 > 0:04:55We now know that that's not true, even though
0:04:55 > 0:04:59we don't know exactly what the strange pockets are for.
0:04:59 > 0:05:03But the camel's hump is certainly not filled with water,
0:05:03 > 0:05:06it's made entirely of fatty tissue.
0:05:06 > 0:05:11It is, in fact, an energy reserve for times when food is scarce
0:05:11 > 0:05:14and it can expand to such a degree that it makes
0:05:14 > 0:05:17up 80% of the camel's body fat.
0:05:17 > 0:05:23This enables a camel to go for two weeks without feeding, if necessary.
0:05:23 > 0:05:26But there's a twist to the story.
0:05:29 > 0:05:34When fat is broken down in the body, it produces not just energy,
0:05:34 > 0:05:36but also water.
0:05:36 > 0:05:39In fact, each gram of fat broken down during metabolism
0:05:39 > 0:05:42produces one gram of water.
0:05:42 > 0:05:47So could the camel's hump provide it with extra water after all?
0:05:49 > 0:05:53A fatty hump that contains both food and water would seem to be
0:05:53 > 0:05:58just what a desert animal needs, but it's not as simple as that.
0:05:58 > 0:06:03To consume its fat, an animal needs more oxygen,
0:06:03 > 0:06:07so it has to breathe more, so when living on the fat in its hump,
0:06:07 > 0:06:12the camel actually loses more water through its airways than it gains.
0:06:12 > 0:06:18So the camel doesn't have a secret store of water.
0:06:18 > 0:06:21How then can it survive in a waterless desert?
0:06:21 > 0:06:25Camels can go without drinking for more than a week
0:06:25 > 0:06:30because they have an extraordinary ability to retain the body moisture.
0:06:31 > 0:06:35We ourselves lose over a litre of water a day
0:06:35 > 0:06:38through our moisture-laden breath.
0:06:38 > 0:06:41But the camel has nostrils which it can shut tight.
0:06:41 > 0:06:44And that not only keeps out the sand,
0:06:44 > 0:06:48but retains the breath within the nose, and there,
0:06:48 > 0:06:52the moisture can be reabsorbed by the linings of the nostrils.
0:06:55 > 0:06:58Most mammals also lose a lot of water
0:06:58 > 0:07:00when they cool their bodies by sweating.
0:07:03 > 0:07:08But camels can endure a rise in body temperature that would kill
0:07:08 > 0:07:10most other mammals without sweating.
0:07:15 > 0:07:18If our temperature goes up by as little as one degree, it's a
0:07:18 > 0:07:20sign of illness.
0:07:20 > 0:07:25While three degrees causes vital organ damage and eventually, death.
0:07:27 > 0:07:31The camel can cope with as much a six degree rise,
0:07:31 > 0:07:33with no ill effect.
0:07:35 > 0:07:38This means that camels don't have to sweat
0:07:38 > 0:07:40until conditions get very hot indeed.
0:07:41 > 0:07:43And if necessary,
0:07:43 > 0:07:47they tolerate losing more of their body water than other mammals.
0:07:49 > 0:07:53When animals become dehydrated, their blood becomes thicker
0:07:53 > 0:07:56and more difficult to pump through the body.
0:07:56 > 0:08:00If we lose 10% of our body water, we start to go dizzy and blind.
0:08:00 > 0:08:05At 15%, our internal organs start to fail.
0:08:05 > 0:08:09Camels however can lose a third of their body water with no ill
0:08:09 > 0:08:13effect, something that would kill most other animals.
0:08:13 > 0:08:15How do they do it?
0:08:15 > 0:08:20Well, some of the answers may lie in the shape of their blood cells.
0:08:20 > 0:08:24These are the red blood cells from a human being,
0:08:24 > 0:08:28which are disc-shaped, like that of most mammals.
0:08:28 > 0:08:32These, on the other hand, are from a camel
0:08:32 > 0:08:35and are slimmer and more oval in shape.
0:08:36 > 0:08:40It may be that the oval, streamlined shape makes it
0:08:40 > 0:08:43easier for the blood to flow when the animal is dehydrated.
0:08:45 > 0:08:50Certainly, a camel's blood is less thick and sticky than ours.
0:08:50 > 0:08:55The cells also have particularly strong walls.
0:08:55 > 0:08:57This prevents them from rupturing
0:08:57 > 0:09:01when the animal suddenly drinks large amounts of water, and when
0:09:01 > 0:09:05they do find water, camels have the ability to drink it very quickly.
0:09:07 > 0:09:10A single camel can take the contents of all these bottles,
0:09:10 > 0:09:14that's 100 litres, in a mere 10 minutes.
0:09:14 > 0:09:17For any other animal to do that, it would be extremely dangerous,
0:09:17 > 0:09:21but the camel has the ability to hold the water in the stomach
0:09:21 > 0:09:25and only release it into the bloodstream very slowly,
0:09:25 > 0:09:27in a way that does no damage.
0:09:30 > 0:09:35We now understand how camels can survive harsh desert conditions.
0:09:35 > 0:09:39And yet, surprisingly, new research suggests that they first have
0:09:39 > 0:09:42evolved to live in the cold Arctic.
0:09:44 > 0:09:49Scientists have recently discovered the fossil bones of giant shaggy
0:09:49 > 0:09:53camels that roamed the forests of the Canadian Arctic
0:09:53 > 0:09:55some 3.5 million years ago.
0:09:57 > 0:10:01The Arctic camel was a third larger than the modern bactrian,
0:10:01 > 0:10:04but otherwise looked very similar.
0:10:04 > 0:10:06And that may be no coincidence.
0:10:07 > 0:10:11The wide, flat feet that stop the camel from sinking into desert
0:10:11 > 0:10:16sand could also have helped its ancestors walk in deep snow.
0:10:17 > 0:10:21And a fatty hump provided the food reserve a camel would need to
0:10:21 > 0:10:23survive long cold winters.
0:10:25 > 0:10:30We may never fully understand the mysteries of the camel's hump,
0:10:30 > 0:10:35whether it evolved first as a way of keeping warm or staying cool.
0:10:35 > 0:10:39But we have unravelled many other mysteries of the animal's
0:10:39 > 0:10:42body that enable it to endure conditions that few other
0:10:42 > 0:10:45animals would be able to withstand.
0:10:47 > 0:10:51The camel's expandable hump was a mystery to us for centuries.
0:10:51 > 0:10:56Our second curiosity can stretch its body in even more
0:10:56 > 0:11:00extraordinary ways and devour prey many times its own size.
0:11:02 > 0:11:07This is a green anaconda, one of the largest snakes in the world.
0:11:07 > 0:11:12It's about four metres long and weighs 70 kilos,
0:11:12 > 0:11:14and it's only half grown.
0:11:14 > 0:11:16They can grow to a length of six metres
0:11:16 > 0:11:19and weigh twice as much as this one.
0:11:19 > 0:11:24But it's their ability to be able to swallow enormous prey that's
0:11:24 > 0:11:26really grabbed our imagination.
0:11:26 > 0:11:30Could one of these really bite a man
0:11:30 > 0:11:33and swallow him whole and alive?
0:11:35 > 0:11:39In the 16th century, European explorers venturing in to the
0:11:39 > 0:11:43Amazon jungle were fascinated by tales of a huge river monster.
0:11:45 > 0:11:49It was said to devour cattle and deer and to spit out
0:11:49 > 0:11:52water like shot from a cannon, knocking animals out of trees.
0:11:54 > 0:11:58These fantastic stories led people to go in search of this
0:11:58 > 0:12:01marvellous beast.
0:12:01 > 0:12:07In 1907, a British explorer, Colonel Percy Fawcett,
0:12:07 > 0:12:13claimed to have encountered an enormous snake on the Amazon River.
0:12:13 > 0:12:16A huge head, he said, rose up from the water,
0:12:16 > 0:12:22dangerously close to his canoe, and a colossal anaconda emerged.
0:12:22 > 0:12:26Greatly alarmed, he shot the snake dead.
0:12:26 > 0:12:31He claimed that when measured, it proved to be nearly 19 metres,
0:12:31 > 0:12:33over 60ft, long.
0:12:33 > 0:12:39But Fawcett's account was met with disbelief and he never provided
0:12:39 > 0:12:42convincing proof because soon after that, he
0:12:42 > 0:12:46vanished into the Brazilian jungle and was never seen again.
0:12:48 > 0:12:51The creature that Fawcett encountered was almost
0:12:51 > 0:12:54certainly a green anaconda.
0:12:54 > 0:12:57Despite their massive proportions,
0:12:57 > 0:13:00these huge snakes are seldom seen because they spend
0:13:00 > 0:13:04most of their time in water, waiting in ambush for their prey.
0:13:07 > 0:13:11In this murky world, they're certainly well camouflaged
0:13:11 > 0:13:14and so some people believed that somewhere,
0:13:14 > 0:13:18another real monster might still be lurking unseen.
0:13:23 > 0:13:26In the 1960s, a snake was brought to the
0:13:26 > 0:13:29Museum Of Zoology at the University College London.
0:13:29 > 0:13:31This is it.
0:13:31 > 0:13:34It had lived in London Zoo for some years before it died
0:13:34 > 0:13:37and it was five metres long.
0:13:37 > 0:13:39A lot of work went into preparing the skeleton.
0:13:39 > 0:13:43It had to be carried out on to the flat roof of the museum
0:13:43 > 0:13:47and it was finally displayed in this rather unusual way -
0:13:47 > 0:13:50wrapped around the branch of a tree.
0:13:53 > 0:13:58For years, the museum displayed it as an anaconda,
0:13:58 > 0:14:00but in 2012,
0:14:00 > 0:14:03a member of the public saw an old photo of the snake
0:14:03 > 0:14:06on the museum's website and pointed out that it
0:14:06 > 0:14:10looked like an African rock python and not an anaconda.
0:14:10 > 0:14:14It's unclear how the mistake came about.
0:14:14 > 0:14:17The markings on the two snakes are quite different.
0:14:17 > 0:14:21But both are giants and there's much controversy as to which
0:14:21 > 0:14:23species is the largest snake of all.
0:14:25 > 0:14:30Anacondas, pythons, and boas, like this one, don't kill with venom.
0:14:30 > 0:14:35They're constrictors. They squeeze their prey to death.
0:14:35 > 0:14:38And their coils can exert a very strong pressure indeed,
0:14:38 > 0:14:42as I can feel with this one on my arm.
0:14:42 > 0:14:47But a big anaconda can squeeze with the force of around 4,000 kilos,
0:14:47 > 0:14:51that's like having a bus on your chest.
0:14:51 > 0:14:55And that can certainly crush the spine of a deer or a capybara.
0:14:58 > 0:15:03And yet, constrictor snakes don't usually crush their prey.
0:15:03 > 0:15:05In most cases, they simply squeeze it
0:15:05 > 0:15:09so hard that the animal can't breathe.
0:15:09 > 0:15:12Every time its prey tries to inhale,
0:15:12 > 0:15:16the snake's powerful muscles squeeze harder.
0:15:16 > 0:15:19The unfortunate victim then either dies
0:15:19 > 0:15:22because its blood can no longer circulate, or suffocates.
0:15:33 > 0:15:37An anaconda, or a python, can kill prey that is not only
0:15:37 > 0:15:42twice its own body size, but many times bigger than its head.
0:15:42 > 0:15:45So how does it manage to swallow its victim whole?
0:15:49 > 0:15:53Popular folklore has it that anacondas
0:15:53 > 0:15:59and pythons unhinge or dislocate their jaws to swallow large prey.
0:15:59 > 0:16:01That is not true.
0:16:01 > 0:16:05They do, however, have the ability to open their mouths wider than
0:16:05 > 0:16:07most animals.
0:16:07 > 0:16:11Pythons and anacondas have this additional bone
0:16:11 > 0:16:14attached to the back of their jaws.
0:16:14 > 0:16:18This provides a double hinge at the joint and allows them
0:16:18 > 0:16:25to open their jaws extremely wide, both downwards and sideways.
0:16:25 > 0:16:29In addition, the two sides of the lower jaw are not fused
0:16:29 > 0:16:33together, but joined by an elastic ligament.
0:16:33 > 0:16:38This gives the jaws a lot of stretch and they can even move apart
0:16:38 > 0:16:41when the snake is swallowing large prey.
0:16:41 > 0:16:46It also allows each side of the jaw to move independently of the other.
0:16:46 > 0:16:49When eating a meal,
0:16:49 > 0:16:52particularly one that is much larger than itself,
0:16:52 > 0:16:57the snake can alternately move its jaws on either side of its head
0:16:57 > 0:17:00and walk its prey into its mouth,
0:17:00 > 0:17:03even while its victim is still alive.
0:17:05 > 0:17:11As the jaws open wide, the snake's elastic skin stretches.
0:17:11 > 0:17:15But the mobility of the skull comes with a price.
0:17:15 > 0:17:19Many of the joints that in other snakes are solid have been
0:17:19 > 0:17:22replaced by mobile ones.
0:17:22 > 0:17:25So the skull has less crushing power.
0:17:25 > 0:17:27As a consequence,
0:17:27 > 0:17:31the snake has to use its entire body to overpower its prey.
0:17:36 > 0:17:41Getting large prey into the mouth is one problem, but how does the snake
0:17:41 > 0:17:44push it all the way down the length of its body, into its stomach?
0:17:47 > 0:17:53This is a Burmese python and it hasn't fed for a long time.
0:17:53 > 0:17:56So I'm hoping to give it a little breakfast.
0:17:56 > 0:17:59With a dead rat.
0:17:59 > 0:18:01What about that?
0:18:12 > 0:18:16Saliva from the salivary glands in the mouth has moistened
0:18:16 > 0:18:19the prey, so it's easier to swallow.
0:18:19 > 0:18:22And now, it's moving its jaws,
0:18:22 > 0:18:26drawing the rat farther down its throat,
0:18:26 > 0:18:28until eventually the muscles of the flanks take over,
0:18:28 > 0:18:33squeezing the prey and pushing against the ribs, so that it
0:18:33 > 0:18:38looks as though the snake is, as it were, crawling around the rat.
0:18:41 > 0:18:44And that will continue for some time,
0:18:44 > 0:18:49as the prey is worked down, in to the snake's body, until
0:18:49 > 0:18:53eventually it reaches the stomach, which is around the middle here.
0:19:00 > 0:19:04Equally remarkable is what happens inside the snake.
0:19:04 > 0:19:08After months of fasting,
0:19:08 > 0:19:11it has to restart its digestive system quickly.
0:19:13 > 0:19:17Within a day, some of the internal organs double in size.
0:19:17 > 0:19:20The heart expands,
0:19:20 > 0:19:23pumping greater volumes of blood around the body
0:19:23 > 0:19:27and special cells in the lining of the stomach produce powerful
0:19:27 > 0:19:30enzymes that break down flesh and bones.
0:19:34 > 0:19:37And when the prey is entirely digested,
0:19:37 > 0:19:40the python's organs return to normal again.
0:19:44 > 0:19:48Anacondas and pythons are able to take in enormous
0:19:48 > 0:19:49meals in a single mouthful.
0:19:52 > 0:19:55But how do they then survive fasting for months on end?
0:19:59 > 0:20:01Like all coldblooded animals,
0:20:01 > 0:20:03snakes get much of their heat from the sun,
0:20:03 > 0:20:07so they need less food to fuel their bodies
0:20:07 > 0:20:11and most of what they eat is converted directly into body mass.
0:20:13 > 0:20:18Snakes continue to grow throughout their lives and anacondas get
0:20:18 > 0:20:23bigger than any other species because they live mostly in water.
0:20:23 > 0:20:26Their massive body is supported by its buoyancy.
0:20:29 > 0:20:33So it's certainly possible that an anaconda could grow to
0:20:33 > 0:20:34an enormous size.
0:20:36 > 0:20:40But how large can a snake really get?
0:20:44 > 0:20:48In 2009, further light was shed on this question with
0:20:48 > 0:20:52the discovery of the fossils of a super snake.
0:20:52 > 0:20:54It was given the name titanoboa
0:20:54 > 0:20:58and it suggests that snakes can get very large indeed.
0:20:59 > 0:21:04Titanoboa was nearly 13 metres long, the length of a bus,
0:21:04 > 0:21:06and must have weighed over a tonne.
0:21:06 > 0:21:08It lived around 60 million years ago,
0:21:08 > 0:21:12shortly after the extinction of the dinosaurs.
0:21:12 > 0:21:13We don't know for sure,
0:21:13 > 0:21:15but it may be that the warmer climate of the Earth
0:21:15 > 0:21:20at the time allowed coldblooded snakes to grow much larger in size.
0:21:20 > 0:21:25What is certain is that for at least 10 million years,
0:21:25 > 0:21:28titanoboa was the largest predator on the planet.
0:21:32 > 0:21:33Both the camel
0:21:33 > 0:21:38and the anaconda can withstand extreme periods of fasting,
0:21:38 > 0:21:42but it's only by looking inside the camel's hump
0:21:42 > 0:21:45and the anaconda's stomach that we've discovered
0:21:45 > 0:21:49the truth behind their amazing expandable bodies.
0:21:56 > 0:22:00The blue whale weighs almost 200 tonnes.
0:22:00 > 0:22:03It's the largest animal on Earth and it's rarely seen.
0:22:03 > 0:22:08I didn't glimpse one until I had been filming animals for almost
0:22:08 > 0:22:1250 years and when I did, it was one of the greatest thrills of my life.
0:22:21 > 0:22:24I can see its tail, just under my boat here.
0:22:24 > 0:22:27And it's coming up... It's coming up...
0:22:27 > 0:22:28There!
0:22:28 > 0:22:34The blue whale is 100ft long.
0:22:34 > 0:22:3530 metres.
0:22:37 > 0:22:40Nothing like that can grow on land
0:22:40 > 0:22:43because no bone is solid enough to support such bulk.
0:22:44 > 0:22:47Only in the sea can you get such
0:22:47 > 0:22:51huge size as that magnificent creature.
0:23:10 > 0:23:14The blue whale was a mystery to science for a long time.
0:23:14 > 0:23:16Living out in the deep oceans,
0:23:16 > 0:23:20people rarely caught sight of more than the spout of this giant.
0:23:20 > 0:23:25The first published description comes from a physician, Robert
0:23:25 > 0:23:31Sibbald, who found a whale stranded off the coast of Scotland in 1692.
0:23:31 > 0:23:34It was first named after Sibbald,
0:23:34 > 0:23:39but later given the scientific name Balaenoptera musculus.
0:23:39 > 0:23:44the Latin "musculus" means both muscle and little mouse,
0:23:44 > 0:23:48an ironic double meaning for the largest animal on Earth.
0:23:51 > 0:23:55When the first blue whale specimens were washed up on our shores,
0:23:55 > 0:23:59they must have caused quite a stir and excitement.
0:23:59 > 0:24:02Here was a colossal animal, weighing over 150 tonnes,
0:24:02 > 0:24:06nothing as big had even been seen before.
0:24:06 > 0:24:09A giant of this scale must be a predator,
0:24:09 > 0:24:11at the top of the food chain.
0:24:11 > 0:24:14But what kind of creature was it?
0:24:14 > 0:24:16And what was it feeding on to make it so big?
0:24:19 > 0:24:23The first blue whale specimens were found at a time
0:24:23 > 0:24:26when scientists were just starting to classify animals, not
0:24:26 > 0:24:30only by their external appearance, but by their internal structures.
0:24:31 > 0:24:35And few animals proved as problematic as the whales.
0:24:37 > 0:24:40From the outside, they looked and behaved like fish,
0:24:40 > 0:24:44but their internal organs were like those of a large mammal.
0:24:47 > 0:24:50The bones of the whale's front fins are very similar to
0:24:50 > 0:24:53those in our own arms.
0:24:53 > 0:24:56The five digits on the hand are clearly visible.
0:24:56 > 0:24:59But they've been modified in to paddles for swimming.
0:25:03 > 0:25:07What kind of creatures were these truly extraordinary animals?
0:25:11 > 0:25:15The controversy as to whether whales were fish or mammals came to
0:25:15 > 0:25:18a head in a New York courtroom in 1818.
0:25:18 > 0:25:20A jury was asked to pass
0:25:20 > 0:25:25judgement on the question for the purpose of the New York state law.
0:25:25 > 0:25:28The issue had come up because a shrewd merchant who owned three
0:25:28 > 0:25:33barrels of whale oil had refused to pay tax levied on fish oil.
0:25:33 > 0:25:37He pointed out that, according to the latest scientific opinion,
0:25:37 > 0:25:39whales weren't in fact fish.
0:25:39 > 0:25:43The inspector collecting the tax had scorned the idea. "What?!
0:25:43 > 0:25:45"Whales not fish?!" he said.
0:25:45 > 0:25:47And slapped handcuffs on the merchant.
0:25:49 > 0:25:54The lead witness was a respected scientist called Samuel Mitchell.
0:25:54 > 0:25:57Mitchell entered the courtroom expecting to explain to
0:25:57 > 0:26:01everybody why whales were mammals, not fish,
0:26:01 > 0:26:05but instead, found himself being attacked by the most gifted
0:26:05 > 0:26:07lawyer in the country, William Sampson.
0:26:09 > 0:26:12Sampson argued that scientists didn't have the right to
0:26:12 > 0:26:16rename God's creatures and force them in to absurd groupings.
0:26:18 > 0:26:19The idea that humans
0:26:19 > 0:26:23and whales should be in the same category seemed to him grotesque.
0:26:26 > 0:26:30Mitchell and science never stood a chance.
0:26:30 > 0:26:33After deliberating for 15 minutes, the jury announced
0:26:33 > 0:26:37the verdict in favour of Sampson and the fish oil inspector.
0:26:37 > 0:26:41According to New York state law, whales were deemed to be fish,
0:26:41 > 0:26:44not mammals.
0:26:46 > 0:26:49Although the general public still considered whales to be fish,
0:26:49 > 0:26:53scientists were by now largely agreed that they were indeed
0:26:53 > 0:26:56mammals that had taken to living in the sea.
0:26:59 > 0:27:03But what was the blue whale feeding on to allow it to grow to
0:27:03 > 0:27:04such an extraordinary size?
0:27:06 > 0:27:09The answer can be found by looking inside the mouth,
0:27:09 > 0:27:12which contains some very bizarre looking structures.
0:27:15 > 0:27:18This is the skeleton of a right whale
0:27:18 > 0:27:22and its mouth parts are very similar to those of the blue whale.
0:27:22 > 0:27:26Instead of teeth, it has these strange plate-like structures
0:27:26 > 0:27:28hanging from the upper jaw.
0:27:28 > 0:27:32The plates are aligned alongside each other and the inner
0:27:32 > 0:27:37edges fray because the large tongue continually rubs up against them.
0:27:37 > 0:27:42And then, the frayed edges entangle to form a thick mat that
0:27:42 > 0:27:44acts like a gigantic sieve.
0:27:45 > 0:27:49And when early naturalists opened up the gigantic gut of these whales,
0:27:49 > 0:27:52they found not fish or other large prey,
0:27:52 > 0:27:56but tiny shrimp-like creatures called krill.
0:27:56 > 0:27:58To everyone's astonishment,
0:27:58 > 0:28:01it turned out that these whales feed on some of the smallest
0:28:01 > 0:28:07prey in the sea and these strange plates serve to filter
0:28:07 > 0:28:08the krill out of the water.
0:28:11 > 0:28:15The rows of plates are called baleen and we now know that they
0:28:15 > 0:28:18form a highly specialised filter feeding system.
0:28:21 > 0:28:24The giant animal dives deep beneath the surface,
0:28:24 > 0:28:26in search of swarms of krill.
0:28:28 > 0:28:30The pleated skin on the throat
0:28:30 > 0:28:34and belly expand and the mouth balloons outward to four
0:28:34 > 0:28:38times the size, taking in an enormous mouthful of water.
0:28:43 > 0:28:46The tongue then forces the water out through the baleen
0:28:46 > 0:28:49and thousands of tiny krill are left behind.
0:28:52 > 0:28:56Today, we know a lot more about this unusual feeding structure.
0:28:58 > 0:29:02This is baleen.
0:29:02 > 0:29:06It's often referred to as whale bone, but it's not bone at all.
0:29:06 > 0:29:10It's keratin, the same substance as our hair and fingernails.
0:29:10 > 0:29:14And it's both strong and slightly elastic.
0:29:14 > 0:29:17The plates emerge from the whale's jaws instead of teeth
0:29:17 > 0:29:21and continue to grow throughout the whale's lifetime.
0:29:21 > 0:29:24These bands in it are much like the rings of a tree.
0:29:24 > 0:29:27Several may be laid down in the course of a year,
0:29:27 > 0:29:31so the baleen can give us an indication of the age of a whale.
0:29:31 > 0:29:34We also know from other evidence that blue whales can live to
0:29:34 > 0:29:36be over 100 years old.
0:29:39 > 0:29:44Recently discovered fossil whales have both teeth and simple filters,
0:29:44 > 0:29:48which suggest that early filter feeding whales may have
0:29:48 > 0:29:50sucked small animals from the sea floor.
0:29:52 > 0:29:57There is a whale alive today that feeds in just that way,
0:29:57 > 0:29:58the grey whale.
0:29:58 > 0:30:03It stirs up the sediment and scoops it in to its mouth
0:30:03 > 0:30:06and then filters out small food particles with its baleen.
0:30:16 > 0:30:19Krill is abundant in the oceans
0:30:19 > 0:30:24and blue whales can eat enormous quantities of it with each mouthful,
0:30:24 > 0:30:28soon swallowing 90 times more than they immediately need.
0:30:28 > 0:30:32The surplus is then stored in the form of blubber
0:30:32 > 0:30:36and this helps them cope with periods when food is scarce.
0:30:40 > 0:30:44The blue whale was a mystery to us for a long time.
0:30:44 > 0:30:48But we now know that its enormous body is fuelled with vast
0:30:48 > 0:30:53quantities of the tiniest of prey. Over the course of its lifetime,
0:30:53 > 0:30:59a blue whale will consume around 50,000 tonnes of krill
0:30:59 > 0:31:02and unlike teeth, which fall out with old age,
0:31:02 > 0:31:06the baleen never stops growing and is constantly replaced.
0:31:06 > 0:31:10Maybe this unusual body design not only helps the blue whale
0:31:10 > 0:31:16grow to this enormous size, but also to such a formidable old age.
0:31:17 > 0:31:21The blue whale has become a giant by filtering tiny creatures
0:31:21 > 0:31:23out of the ocean.
0:31:24 > 0:31:27Our second curiosity, the flamingo,
0:31:27 > 0:31:31also has an unusual body that has been shaped by its diet.
0:31:35 > 0:31:40For a long time, the flamingos were birds of myth and mystery.
0:31:40 > 0:31:44Travellers in Africa saw them shrouded by the hazy mists,
0:31:44 > 0:31:49rising from volcanic soda lakes and believed that they were firebirds.
0:31:51 > 0:31:54In Egyptian mythology, the firebird, or phoenix,
0:31:54 > 0:31:58was a sacred creature with beautiful red plumage that was
0:31:58 > 0:32:03consumed by magical fire and then rose again from its own ashes.
0:32:05 > 0:32:08The flamingo's scientific name, Phoenicopterus,
0:32:08 > 0:32:11reflects some of its legendary past.
0:32:11 > 0:32:14It means phoenix wing.
0:32:14 > 0:32:15These beautiful
0:32:15 > 0:32:20and elegant creatures are some of the most curious looking of birds.
0:32:20 > 0:32:24No other bird has a beak shaped quite like this.
0:32:24 > 0:32:27Or indeed such glorious pink colours.
0:32:27 > 0:32:29And yet, we're so familiar with them that we
0:32:29 > 0:32:33rarely think about their strange appearance.
0:32:33 > 0:32:37Why is it that the flamingo is so different from all other birds?
0:32:39 > 0:32:41In that classic children's book,
0:32:41 > 0:32:46Alice In Wonderland, Lewis Carroll has fun with the flamingo's oddity.
0:32:48 > 0:32:52Alice plays croquet with the Red Queen, using them as mallets,
0:32:52 > 0:32:55holding their heads and necks upside down,
0:32:55 > 0:32:59in much the same posture as the birds take when feeding.
0:33:02 > 0:33:06When you look at the skeleton of a flamingo, the thing that strikes
0:33:06 > 0:33:11you most is the extraordinary length of the legs and the neck.
0:33:11 > 0:33:14The neck has 17 bones in it,
0:33:14 > 0:33:18which is no more than in other birds, but each is greatly
0:33:18 > 0:33:24elongated, giving the flamingo its extra long neck and flexibility.
0:33:24 > 0:33:28But the flamingo's most curious feature is surely its beak.
0:33:28 > 0:33:30And the reason it looks
0:33:30 > 0:33:36so strange is that it is the only beak adapted for use upside down.
0:33:36 > 0:33:41In most birds, the upper part of the bill is larger than the lower
0:33:41 > 0:33:45one, but in the flamingo's, it's the other way round.
0:33:45 > 0:33:47The lower bill is much bigger
0:33:47 > 0:33:51and has a deep central groove in it that holds the flamingo's tongue.
0:33:53 > 0:33:59The upper jaw is thin and moveable, so when the bird's head is
0:33:59 > 0:34:05upside down, the flamingo's jaws work, as it were, normally.
0:34:10 > 0:34:15When feeding, the flamingo gently sweeps its bill back and forth,
0:34:15 > 0:34:19sucking water in at the front and squirting it out from the sides.
0:34:26 > 0:34:30The water that goes in is murky, while that which flows out is
0:34:30 > 0:34:34clear and that gives us a clue to what it's feeding on.
0:34:38 > 0:34:42The beak has tiny bristles all along its edges,
0:34:42 > 0:34:43much like the whale's baleen.
0:34:47 > 0:34:51And the tongue has two rows of horny spikes along its length.
0:34:56 > 0:34:59When feeding, the bristles and spikes form a sieve,
0:34:59 > 0:35:01trapping any particles inside.
0:35:04 > 0:35:09And the large tongue acts as a pump, pushing water in and out.
0:35:12 > 0:35:17It's a unique design for a beak. No other bird has one like it.
0:35:21 > 0:35:25Although at first sight, they may look the same,
0:35:25 > 0:35:28flamingo beaks in fact come in two different shapes.
0:35:29 > 0:35:32This is because they eat slightly different food.
0:35:35 > 0:35:39This is the beak of a greater flamingo,
0:35:39 > 0:35:41which feeds on crustaceans,
0:35:41 > 0:35:45which are usually found near the bottom of a lake.
0:35:45 > 0:35:47It's long and shallow,
0:35:47 > 0:35:50so the birds can feed in water only a few millimetres deep.
0:35:52 > 0:35:56This beak, on the other hand, is from a lesser flamingo.
0:35:56 > 0:36:00Its bill is shorter, but more bulbous and deep-keeled.
0:36:00 > 0:36:05The lesser flamingo feeds on microscopic algae,
0:36:05 > 0:36:08which usually float just below the surface of the water,
0:36:08 > 0:36:13and the deep keel acts as a buoy, bobbing along just at the
0:36:13 > 0:36:16right depth, as the bird moves through the water.
0:36:21 > 0:36:25These different bills allow two species of flamingo to live
0:36:25 > 0:36:26side by side.
0:36:28 > 0:36:33In Africa's Rift Valley, greater and lesser flamingos are found on
0:36:33 > 0:36:38the soda lakes, having specialised on food that others can't reach.
0:36:41 > 0:36:44The waters are so hot and toxic that they would strip
0:36:44 > 0:36:48the flesh off any other animal, but flamingos thrive here.
0:36:53 > 0:36:56Their long spindly legs have tough scales
0:36:56 > 0:37:00and their webbed feet prevent them from sinking in to the soft mud.
0:37:02 > 0:37:05The birds can even drink the water, which is
0:37:05 > 0:37:07two or three times saltier than the ocean.
0:37:11 > 0:37:14But it's not just the mud and water which are poisonous.
0:37:16 > 0:37:19The blue green algae, which many of them feed on,
0:37:19 > 0:37:23actually contain nasty toxic chemicals.
0:37:23 > 0:37:27If that were to accumulate in the internal organs of the bird,
0:37:27 > 0:37:28they could be lethal.
0:37:28 > 0:37:31But the flamingo deals with that by directing these
0:37:31 > 0:37:36chemicals into the feathers and the skin, where they do no damage.
0:37:37 > 0:37:40The feathers of flamingos contain very high concentrations
0:37:40 > 0:37:46of toxins, but they also contain another chemical, carotene.
0:37:46 > 0:37:50Carotene is the reddish pigment that gives
0:37:50 > 0:37:53flamingos their distinctive pink colour.
0:37:53 > 0:37:57And it also comes from their diet. But carotene is not harmful.
0:37:57 > 0:38:00On the contrary, it's a source of vitamin
0:38:00 > 0:38:05and boosts the immune system, protecting against illness,
0:38:05 > 0:38:08so a pink bird is also a healthy bird.
0:38:13 > 0:38:17This glorious pink colour was probably an incidental
0:38:17 > 0:38:19by-product of their diet.
0:38:19 > 0:38:21Nonetheless over time,
0:38:21 > 0:38:26it's evolved to play an important role in the flamingo's social life.
0:38:26 > 0:38:29The flashes of colour are an integral part of their
0:38:29 > 0:38:34courtship display and recent research has shown that the pinkest
0:38:34 > 0:38:38flamingos are the most popular when it comes to finding a mate.
0:38:43 > 0:38:48When flamingos breed, much of the carotene in their diet gets
0:38:48 > 0:38:50channelled into the developing young.
0:38:50 > 0:38:53Even the eggs receive pigments.
0:38:53 > 0:38:58So much, in fact, that the yolk can be virtually blood red in colour.
0:38:58 > 0:39:03These eggs are from captive flamingos and are infertile.
0:39:03 > 0:39:05Let's have a look.
0:39:06 > 0:39:07There.
0:39:10 > 0:39:14Well, it's nothing like the colour or any other bird yolk that
0:39:14 > 0:39:17I've ever seen.
0:39:17 > 0:39:20Flamingos are so efficient at collecting their specialised
0:39:20 > 0:39:24food that the yolk is actually packed full of protein and fat.
0:39:24 > 0:39:28And this allows the chick to grow particularly quickly
0:39:28 > 0:39:30and gives it a good start in life.
0:39:35 > 0:39:37Despite the colour of the yolk,
0:39:37 > 0:39:40the chicks hatch with fluffy grey feathers.
0:39:41 > 0:39:45They're fed on special milk from their parents' crop.
0:39:45 > 0:39:48This is not regurgitated food,
0:39:48 > 0:39:53but a secretion produced by the lining of the digestive tract.
0:39:53 > 0:39:55And it's deep red in colour.
0:40:04 > 0:40:09The flamingo chick relies on this for the first few weeks of its life.
0:40:10 > 0:40:13And it will eventually enable it to grow its glorious pink plumes.
0:40:18 > 0:40:21We now know that much of the flamingo's bizarre
0:40:21 > 0:40:24appearance has been shaped by its diet.
0:40:24 > 0:40:27But one question continues to baffle scientists -
0:40:27 > 0:40:30to which group of birds do the flamingos actually belong?
0:40:31 > 0:40:34Some thought that they must be related to ducks and geese
0:40:34 > 0:40:38because of their webbed feet and short duck-like beaks.
0:40:38 > 0:40:41But others were convinced that with their long legs,
0:40:41 > 0:40:44they're more like waders, such as storks.
0:40:46 > 0:40:50Recent DNA studies contradict both these suggestions.
0:40:52 > 0:40:56They reveal that the flamingo's closest relative may in fact
0:40:56 > 0:41:00be a small diving bird that looks nothing like a flamingo.
0:41:01 > 0:41:03The grebe.
0:41:06 > 0:41:09Further studies found other similarities in the structure
0:41:09 > 0:41:12of the eye and the number of feathers on the wing.
0:41:17 > 0:41:18So, it seems that flamingos
0:41:18 > 0:41:22and grebes are indeed each other's closest relatives.
0:41:22 > 0:41:27But over time, diet and lifestyle has shaped the flamingo into a very
0:41:27 > 0:41:31different looking bird, far removed from its grebe-like ancestor.
0:41:37 > 0:41:41It's fair to say there's nothing else quite like a flamingo.
0:41:46 > 0:41:50The flamingo and the blue whale are two very different creatures,
0:41:50 > 0:41:54one living on land and one in the deep oceans.
0:41:54 > 0:41:57And yet their bodies have been shaped in a similar way,
0:41:57 > 0:41:59by their diet,
0:41:59 > 0:42:02making each of them a curiosity within its own group.