0:00:02 > 0:00:05The natural world is full of extraordinarily shaped creatures...
0:00:06 > 0:00:10..but how have the stretched bodies of some given them an edge?
0:00:12 > 0:00:13I have had the fortune to meet
0:00:13 > 0:00:16some of the planet's most enchanting creatures -
0:00:16 > 0:00:19but some stand out more than others
0:00:19 > 0:00:21because of their intriguing biology.
0:00:23 > 0:00:27Our knowledge of some of these creatures extends back centuries.
0:00:27 > 0:00:29Others, we've discovered more recently.
0:00:32 > 0:00:35In this series, I share their stories
0:00:35 > 0:00:40and reveal why they are considered natural curiosities.
0:00:45 > 0:00:48In this programme, I investigate two creatures
0:00:48 > 0:00:52that have taken the ordinary and make it extraordinary.
0:00:53 > 0:00:57The chameleon, that has an extra long tongue to catch prey...
0:00:58 > 0:01:03..and the giraffe, with a neck so long it can reach the top of trees.
0:01:05 > 0:01:09How and why have these animals stretched nature to the limit?
0:01:20 > 0:01:24The chameleon is a truly bizarre creature,
0:01:24 > 0:01:26both in its behaviour and its appearance
0:01:26 > 0:01:29unlike anything else on Earth.
0:01:29 > 0:01:31So, not surprisingly, it has given rise
0:01:31 > 0:01:34to all kinds of legends and myths.
0:01:34 > 0:01:37This is the History of the Four-Footed Beasts
0:01:37 > 0:01:39by Edward Topsell,
0:01:39 > 0:01:43written in the 17th century, and he calls the chameleon
0:01:43 > 0:01:46"a fraudulent, ravening and gluttonous beast,
0:01:46 > 0:01:50"impure and unclean by the law of God."
0:01:51 > 0:01:54Some believed it was constructed by the devil
0:01:54 > 0:01:56from parts of other animals -
0:01:56 > 0:02:01the tail of a monkey, the skin of a crocodile, the tongue of a toad,
0:02:01 > 0:02:06the horns of a rhinoceros, and the eyes of - who knows what?
0:02:06 > 0:02:10It was a creature sent to the world to spy for a demon master.
0:02:12 > 0:02:16When I first came face to face with a chameleon, more than 50 years ago,
0:02:16 > 0:02:22I was struck not only by its beauty, but intrigued by its strange body.
0:02:22 > 0:02:24Particularly by its tongue.
0:02:28 > 0:02:31The outlandish appearance of the chameleon made it much sought after
0:02:31 > 0:02:33by curiosity hunters -
0:02:33 > 0:02:36but scientists and naturalists, too,
0:02:36 > 0:02:40were greatly puzzled by its extraordinary behaviour and anatomy.
0:02:43 > 0:02:46It looked and behaved like no other reptile.
0:02:48 > 0:02:54Even today, we are still discovering new things about its unique eyes,
0:02:54 > 0:02:56its astonishing tongue,
0:02:56 > 0:02:59and its ability to change its appearance.
0:03:03 > 0:03:06Chameleons are notoriously hard to find.
0:03:06 > 0:03:09Partly because they move so slowly,
0:03:09 > 0:03:11but also because they match their surroundings,
0:03:11 > 0:03:14in terms of colour, so very well.
0:03:14 > 0:03:17This one in front of me is a dwarf chameleon
0:03:17 > 0:03:19from Natal in South Africa.
0:03:19 > 0:03:22If it is threatened by a snake,
0:03:22 > 0:03:25it doesn't bother to change its colour very much
0:03:25 > 0:03:27because a snake's colour vision is not very good,
0:03:27 > 0:03:30but if it is threatened by a bird,
0:03:30 > 0:03:33it does camouflage itself very well indeed.
0:03:36 > 0:03:38Some species of chameleon -
0:03:38 > 0:03:41and there are 85 different species in the family -
0:03:41 > 0:03:44can even fine-tune their camouflage.
0:03:46 > 0:03:48If they detect a snake approaching from below,
0:03:48 > 0:03:53they become lighter in colour and so less noticeable against the sky.
0:03:55 > 0:03:58On the other hand, if the threat comes from above,
0:03:58 > 0:04:01they become darker to match the background beneath them.
0:04:03 > 0:04:08A chameleon's colour is affected not only by its surroundings,
0:04:08 > 0:04:13but by the temperature and the light and its emotional state.
0:04:13 > 0:04:16Behind this screen, there is a rival male.
0:04:16 > 0:04:19Let's see what happens if I remove the screen
0:04:19 > 0:04:21and let them see one another.
0:04:23 > 0:04:26This highly coloured male is dominant,
0:04:26 > 0:04:29and he immediately adds bright, aggressive colours to his display.
0:04:30 > 0:04:32The other male remains dark
0:04:32 > 0:04:36and too frightened to change colour and fight back.
0:04:36 > 0:04:38It's clear who's the boss.
0:04:43 > 0:04:46Chameleons are emotional creatures.
0:04:46 > 0:04:49Darker colouration signals anger.
0:04:49 > 0:04:52This female on the right is not in the mood to accept the approaches
0:04:52 > 0:04:55of this brightly coloured and hopeful male.
0:05:04 > 0:05:08Exactly how chameleons achieve such dramatic colour changes
0:05:08 > 0:05:10greatly puzzled early naturalists.
0:05:12 > 0:05:14An Englishman named Barrow,
0:05:14 > 0:05:16who travelled in Africa in the 19th century,
0:05:16 > 0:05:21thought that changing colour was caused by something to do with air.
0:05:21 > 0:05:25He wrote, "Previous to the chameleon assuming a change in colour,
0:05:25 > 0:05:27"it makes a long inspiration,
0:05:27 > 0:05:30"the body swelling up to twice its usual size,
0:05:30 > 0:05:33"and as this inflation subsides,
0:05:33 > 0:05:36"the change of colour gradually takes place."
0:05:36 > 0:05:39Well, that's an accurate observation of what happens
0:05:39 > 0:05:43when a chameleon gets angry, and then its anger subsides -
0:05:43 > 0:05:47but actually the change of colour has nothing to do with air.
0:05:47 > 0:05:53A French biologist, Milne-Edwards, soon after that got it about right.
0:05:53 > 0:05:55He wrote,
0:05:55 > 0:05:57"There exist two layers of membranous pigment
0:05:57 > 0:05:59"placed one above the other,
0:05:59 > 0:06:02"but disposed in such a way to appear simultaneously
0:06:02 > 0:06:04"under the cuticle
0:06:04 > 0:06:09"and sometimes in such a manner that one may hide the other."
0:06:09 > 0:06:10Which is indeed so.
0:06:12 > 0:06:16Today, we know that the chameleon's skin has three layers
0:06:16 > 0:06:21of expandable pigmented cells called chromatophores.
0:06:21 > 0:06:25They contain red, yellow, blue and white pigments,
0:06:25 > 0:06:27with a deeper layer of darker melanin,
0:06:27 > 0:06:29which controls the reflection of light.
0:06:32 > 0:06:37The chameleons use colour change not only to camouflage themselves,
0:06:37 > 0:06:40but also to communicate with one another.
0:06:42 > 0:06:45Anyone who looks closely at a chameleon
0:06:45 > 0:06:48is bound to be fascinated by its eyes.
0:06:49 > 0:06:53They protrude on either side of its heads,
0:06:53 > 0:06:55as though they were mounted on turrets.
0:06:56 > 0:07:01And in fact, their eyelids are fused together,
0:07:01 > 0:07:05except for one tiny spot right in the middle.
0:07:05 > 0:07:08But the most extraordinary thing about them
0:07:08 > 0:07:11is that they move independently.
0:07:11 > 0:07:15So that means the chameleon at one and the same time
0:07:15 > 0:07:18can be viewing above it and below it,
0:07:18 > 0:07:21so any insect that lands nearby
0:07:21 > 0:07:24is going to be spotted almost immediately.
0:07:26 > 0:07:29It seems that its brain
0:07:29 > 0:07:32receives separate messages
0:07:32 > 0:07:33from each eye
0:07:33 > 0:07:35and views them and receives them
0:07:35 > 0:07:37alternately, very fast,
0:07:37 > 0:07:39but independent to one another.
0:07:39 > 0:07:42They are not integrated.
0:07:42 > 0:07:44But the advantage of that
0:07:44 > 0:07:48is that it does give this all-round three-dimensional view
0:07:48 > 0:07:50which is unrivalled.
0:07:54 > 0:07:57This extraordinary vision is an essential element
0:07:57 > 0:08:01in the way the chameleon uses its most astonishing feature,
0:08:01 > 0:08:04its hugely elongated tongue.
0:08:05 > 0:08:08How this tongue worked and its construction
0:08:08 > 0:08:11greatly intrigued early naturalists -
0:08:11 > 0:08:12and understandably.
0:08:19 > 0:08:23This remarkable preserved specimen shows us in detail
0:08:23 > 0:08:27the impressive elongated tongue of a chameleon.
0:08:27 > 0:08:29The physical structure
0:08:29 > 0:08:32of the chameleon's tongue was easy enough to explain,
0:08:32 > 0:08:35although it proved to be a somewhat complicated organ -
0:08:35 > 0:08:36a hollow tube
0:08:36 > 0:08:40with a tapered cartilaginous rod at its base.
0:08:40 > 0:08:43The pad at the end
0:08:43 > 0:08:45was thought to be rough and sticky
0:08:45 > 0:08:47so that it could snag its prey.
0:08:47 > 0:08:50But the mystery of how a contraption like this
0:08:50 > 0:08:54could be lengthened and projected out of the mouth
0:08:54 > 0:08:57took a little longer to fully explain.
0:08:57 > 0:09:02Perhaps the way a frigate bird inflates the balloon under its beak,
0:09:02 > 0:09:06or how a calling frog blows up its throat sac could give clues.
0:09:06 > 0:09:08Both do it with air.
0:09:08 > 0:09:12Or maybe the tentacles that carry a snail's eyes -
0:09:12 > 0:09:16it projects them by using its blood as a hydraulic fluid.
0:09:17 > 0:09:19But none of them fitted the bill.
0:09:21 > 0:09:23It is a much more complex process.
0:09:23 > 0:09:27The tongue is a muscular tube that, when relaxed,
0:09:27 > 0:09:29sits on a rod of cartilage.
0:09:29 > 0:09:32When the chameleon is ready to strike,
0:09:32 > 0:09:37muscles at the back of the tongue push it into launch position.
0:09:37 > 0:09:40When the prey is lined up and the distance detected,
0:09:40 > 0:09:42superfast muscles contract
0:09:42 > 0:09:45and propel the tongue forward at lightning speed.
0:09:48 > 0:09:51As the tongue shoots off the end of the cartilage,
0:09:51 > 0:09:54an extra wave of energy drives it forward to its target.
0:09:56 > 0:09:59Then, like a stretched elastic band,
0:09:59 > 0:10:03its elasticity pulls it back into the chameleon's mouth.
0:10:10 > 0:10:15Recently, high speed images revealed a new detail.
0:10:15 > 0:10:18The tip of the tongue, once thought to be sticky,
0:10:18 > 0:10:20is covered in microscopic protrusions
0:10:20 > 0:10:24that generate suction and secure its prey.
0:10:31 > 0:10:34Chameleons really are the most extraordinary creatures,
0:10:34 > 0:10:37and they hold surprises for us even today.
0:10:38 > 0:10:39Only this year,
0:10:39 > 0:10:44a scientist working in Madagascar discovered a tiny little chameleon,
0:10:44 > 0:10:47only 29 millimetres long.
0:10:47 > 0:10:50It's the smallest known vertebrate in the world.
0:10:50 > 0:10:53It's astounding to realise
0:10:53 > 0:10:56that all the organs of a vertebrate body
0:10:56 > 0:11:00could be fitted into such a tiny little creature -
0:11:00 > 0:11:03including that extraordinary tongue.
0:11:06 > 0:11:10Next is the story of another amazing elongated structure.
0:11:11 > 0:11:14Not a tongue, but a neck.
0:11:18 > 0:11:22The giraffe is an animal that can't fail to impress.
0:11:22 > 0:11:27Up to six metres or 19 feet in height, it's hugely imposing,
0:11:27 > 0:11:30intriguing in appearance and mysterious in its biology.
0:11:31 > 0:11:35Our attraction to this unusual creature goes back centuries,
0:11:35 > 0:11:38and one feature in particular has piqued our curiosity -
0:11:38 > 0:11:40its elongated neck.
0:11:41 > 0:11:45Such a structure seemed an impossibility of nature,
0:11:45 > 0:11:48but now we better understand the complex biology
0:11:48 > 0:11:51behind the giraffe's bizarre body.
0:11:51 > 0:11:54Our growing knowledge of this creature
0:11:54 > 0:11:57can be traced back to three very special giraffes
0:11:57 > 0:12:01and the story of a royal fascination for the exotic.
0:12:03 > 0:12:09In the 19th century, a giraffe named Zarafa, Arabic for charming one,
0:12:09 > 0:12:12made a big impact on Europe, socially and scientifically.
0:12:14 > 0:12:17She was one of three captured in 1826
0:12:17 > 0:12:19at the order of the Viceroy of Egypt,
0:12:19 > 0:12:22who wanted to use them as gifts
0:12:22 > 0:12:25to curry favour with France, Austria, and England.
0:12:27 > 0:12:30Zarafa, the strongest of the three, was given to the French,
0:12:30 > 0:12:35seen here in a painting by Jacques Raymond Brascassat.
0:12:35 > 0:12:39She travelled from Egypt to Marseille by ship.
0:12:41 > 0:12:42On reaching France,
0:12:42 > 0:12:46her keepers thought it was too risky to continue by boat,
0:12:46 > 0:12:52so the decision was made to walk Zarafa from Marseille in the south
0:12:52 > 0:12:53all the way to Paris -
0:12:53 > 0:12:55an overland journey
0:12:55 > 0:12:58of more than 550 miles.
0:12:58 > 0:13:00To some, this looked like a journey
0:13:00 > 0:13:01doomed to failure.
0:13:01 > 0:13:05But careful planning and the unique biology of the giraffe
0:13:05 > 0:13:07were in its favour.
0:13:07 > 0:13:11Very wisely, the forward-thinking and eminent French scientist
0:13:11 > 0:13:16called Geoffroy Saint-Hilaire was put in charge of the giraffe.
0:13:16 > 0:13:19But there was something very significant about Zarafa
0:13:19 > 0:13:22that would be key to the success of her long journey.
0:13:22 > 0:13:24It was her age.
0:13:24 > 0:13:27She was a youngster, just eight months old.
0:13:29 > 0:13:31Baby giraffes are very robust,
0:13:31 > 0:13:35and can stand up and run within an hour of being born.
0:13:35 > 0:13:39They have particularly long legs in relation to their bodies,
0:13:39 > 0:13:43only half a metre shorter than those of an adult.
0:13:44 > 0:13:47Such long legs help them keep up with their mothers,
0:13:47 > 0:13:51so young Zarafa was well-equipped for walking.
0:13:56 > 0:14:00Crucial, too, was the fuel for Zarafa's journey.
0:14:00 > 0:14:03Young giraffes suckle for up to a year,
0:14:03 > 0:14:05and Zarafa was bottle-fed.
0:14:05 > 0:14:07Throughout the journey,
0:14:07 > 0:14:10she drank up to 25 litres of milk a day
0:14:10 > 0:14:13supplied by three milking cows.
0:14:17 > 0:14:21She marched on at a steady pace with her trusty entourage.
0:14:24 > 0:14:28After nearly 200 miles, Zarafa reached Lyon
0:14:28 > 0:14:30and Saint-Hilaire broke the walk.
0:14:30 > 0:14:33He hoped to put is Zarafa onto a boat,
0:14:33 > 0:14:35to go downriver for the rest of the journey.
0:14:35 > 0:14:40As they waited, 30,000 people flocked to see Zarafa.
0:14:40 > 0:14:44To the public, she was a strange and exotic creature,
0:14:44 > 0:14:48and they were intrigued why such a long neck should exist,
0:14:48 > 0:14:51and curious about how an animal could support its weight.
0:14:51 > 0:14:55In those early days, giraffes were seen as freaks -
0:14:55 > 0:14:58strange, horned camels whose humps had been flattened
0:14:58 > 0:15:00by the stretching of their necks.
0:15:00 > 0:15:05But this was exactly what attracted Saint-Hilaire to Zarafa.
0:15:05 > 0:15:09He was fascinated by genetic exaggerations
0:15:09 > 0:15:11and how they came to be.
0:15:11 > 0:15:14Clearly, the giraffe's long neck enables them to feed on leaves
0:15:14 > 0:15:17beyond the reach of other browsers.
0:15:18 > 0:15:22But how could they physically hold up such a long neck vertically?
0:15:25 > 0:15:26HE CHUCKLES
0:15:26 > 0:15:28Studies of giraffe anatomy
0:15:28 > 0:15:32have revealed just how the neck is supported.
0:15:32 > 0:15:37A long, thick ligament like a cable runs the whole length of the neck.
0:15:37 > 0:15:41This counterbalances the weight of the head and the neck,
0:15:41 > 0:15:44and, in its relaxed position, it's tight,
0:15:44 > 0:15:47so keeping the neck straight and the head up
0:15:47 > 0:15:50involves very little muscular effort.
0:15:50 > 0:15:53Bending the neck to reach down is more difficult,
0:15:53 > 0:15:57because the tough ligament has to be stretched.
0:15:58 > 0:16:02But was the ability to feed from tall trees
0:16:02 > 0:16:05the only reason for having a long neck?
0:16:05 > 0:16:09As the habits of giraffe in the wild became better known,
0:16:09 > 0:16:13people discovered that rival males fought one another
0:16:13 > 0:16:15by jousting with their necks.
0:16:15 > 0:16:18Was that the reason that they had developed long necks?
0:16:18 > 0:16:23But then someone pointed out that the females had long necks too,
0:16:23 > 0:16:25so that suggestion was discarded.
0:16:25 > 0:16:29In truth, there isn't a neat, single answer.
0:16:29 > 0:16:31But access to high food,
0:16:31 > 0:16:34better vigilance and temperature regulation
0:16:34 > 0:16:37may all have shaped the giraffe's long neck.
0:16:39 > 0:16:44As she walked on, Zarafa continued to attract inquisitive onlookers.
0:16:44 > 0:16:46Few had set eyes on such a creature.
0:16:46 > 0:16:48She appeared a natural impossibility.
0:16:49 > 0:16:54How could a giraffe pump the blood up such a long neck to its brain?
0:16:54 > 0:16:58And why didn't the blood rush back down into its feet?
0:17:01 > 0:17:04The giraffe's neck may be very tall,
0:17:04 > 0:17:09but in fact, it contains exactly the same number of bones as our own -
0:17:09 > 0:17:10that is to say, seven.
0:17:10 > 0:17:14But its blood pressure is twice as high as ours.
0:17:14 > 0:17:18In fact, it's higher than any other known animal.
0:17:18 > 0:17:22The pump that produces this pressure - the heart -
0:17:22 > 0:17:26surprisingly, is not particularly big, but it is unusually powerful.
0:17:26 > 0:17:29This is the left ventricle, that has been cut through,
0:17:29 > 0:17:32and you can see how thick the muscle is,
0:17:32 > 0:17:35getting on for about eight centimetres.
0:17:35 > 0:17:38This great pump produces blood,
0:17:38 > 0:17:41squirts it up the artery to the head,
0:17:41 > 0:17:45and then, when it comes down through the jugular vein,
0:17:45 > 0:17:47there are pocket-shaped valves
0:17:47 > 0:17:50which prevent the blood from flowing backwards into the head
0:17:50 > 0:17:53if the animal lowers its head in order to have a drink.
0:17:54 > 0:17:58Giraffes find it very awkward to drink from the ground,
0:17:58 > 0:18:00and, in fact, they rarely do so.
0:18:00 > 0:18:03They get most of their water from leaves and shoots.
0:18:04 > 0:18:07The only way to get their mouths down to the water
0:18:07 > 0:18:11is to splay their four legs or bend them at the wrist joint.
0:18:14 > 0:18:17The giraffe, in fact, has a relatively short neck
0:18:17 > 0:18:19compared to its legs.
0:18:21 > 0:18:24Antelope and zebra can reach down to the ground
0:18:24 > 0:18:26without bending their legs.
0:18:26 > 0:18:29Only the giraffe and its rainforest relative the okapi
0:18:29 > 0:18:33have necks that are so short relative to their legs
0:18:33 > 0:18:35that they must splay or bend them.
0:18:36 > 0:18:39So perhaps the most remarkable feature of the giraffe
0:18:39 > 0:18:41is the length of its legs.
0:18:41 > 0:18:45They certainly were key to Zarafa's success.
0:18:45 > 0:18:48At Lyon, there was a plan to rest her legs from walking
0:18:48 > 0:18:51and to finish the journey to Paris by boat -
0:18:51 > 0:18:53but all didn't go according to plan.
0:18:55 > 0:18:57The boat didn't appear in Lyon,
0:18:57 > 0:19:01so she walked on and finally got to Paris.
0:19:01 > 0:19:03It took her a total of 41 days
0:19:03 > 0:19:07to complete the journey of 550 miles to Paris.
0:19:07 > 0:19:11Saint-Hilaire, her trusty companion, was exhausted -
0:19:11 > 0:19:14but the giraffe was very fit.
0:19:14 > 0:19:17He wrote, "She gained weight and much more strength
0:19:17 > 0:19:19"from the exercise.
0:19:19 > 0:19:21"Her muscles are more defined,
0:19:21 > 0:19:24"her coat smoother and glossier upon her arrival
0:19:24 > 0:19:26"than they were in Marseille."
0:19:26 > 0:19:30Zarafa was presented to King Charles X
0:19:30 > 0:19:33and temporarily installed in a greenhouse
0:19:33 > 0:19:36in the grounds of the Jardin des Plantes.
0:19:36 > 0:19:38She was a true animal ambassador
0:19:38 > 0:19:42and 60,000 people saw her in the first three weeks in Paris.
0:19:43 > 0:19:47In the early 19th century, giraffes were a novelty,
0:19:47 > 0:19:51and their biology and lives in the wild were still a mystery.
0:19:51 > 0:19:56Zarafa's success was due to a unique interplay
0:19:56 > 0:19:59of the giraffe's unusual characteristics and good timing.
0:19:59 > 0:20:02Her youth, long legs,
0:20:02 > 0:20:07and a diet with milk powered her journey right across France.
0:20:09 > 0:20:12Her body, that was first considered bizarre,
0:20:12 > 0:20:15was revealed to be perfectly evolved.
0:20:18 > 0:20:22Our story began with three giraffes that were given to Europe.
0:20:22 > 0:20:28Zarafa was the most robust of them, and she lived a further 18 years.
0:20:28 > 0:20:31The Austrian one lasted just a year,
0:20:31 > 0:20:35and the one sent to King George the fourth of England died after two.
0:20:36 > 0:20:39Saint-Hilaire learned much from Zarafa,
0:20:39 > 0:20:41and he became a key figure
0:20:41 > 0:20:44in the blossoming zoological research in France.
0:20:44 > 0:20:46The giraffe brought to England
0:20:46 > 0:20:48triggered a surge of interest in animal research
0:20:48 > 0:20:51that shifted the centre of zoological gravity
0:20:51 > 0:20:53from France to England.
0:20:53 > 0:20:57So, we can thank Zarafa for her early role
0:20:57 > 0:21:00in unravelling the biological mysteries
0:21:00 > 0:21:04of the giraffe's extraordinary body and stretched neck.
0:21:06 > 0:21:10Creatures like the outlandish giraffe and chameleon
0:21:10 > 0:21:14continue to reveal their biological secrets.
0:21:14 > 0:21:17They really are true natural curiosities.