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00:30Reptiles and amphibians are sometimes thought of as primitive, dull and dim-witted.
00:44In fact, of course, they can be lethally fast, spectacularly beautiful, surprisingly affectionate
00:51and very sophisticated. They have remarkably varied ways of catching their prey and of
01:06defending themselves. They can produce a great turn of speed and fight with impressive zest.
01:21Some have spectacular colours and show off to one another. They communicate with calls
01:38and with gestures. And there, that's it.
01:52The full works.
01:56Reptiles have scaly skins and amphibians soft, moist ones.
02:06None of them live at a uniform pace, but switch from the fast to the slow lane within a year or an hour.
02:14Unlike us, they get their energy directly from the sun.
02:24And although being called cold-blooded might suggest they're unemotional, they can be touchingly warm-hearted,
02:31as mates and as parents.
02:44And that's just the beginning. There are a whole lot of other warm-hearted truths to be discovered
02:57that give the phrase life in cold blood a completely new meaning.
03:05The Galapagos Islands.
03:15Some of the reptiles that live here are particularly skilful at solving the problems of getting their energy
03:22directly from sunshine.
03:26Marine iguanas face a major thermal challenge every morning of their lives.
03:33During the night, their bodies cool, and now they must warm up quickly in order that they can become active
03:40and start feeding.
03:43Their bodies and skins are black, which is very efficient at absorbing heat.
03:49And they bask with their black flanks broad-tied to the sun.
03:57The rate at which they absorb warmth is invisible to the naked eye, but very clear indeed to a thermal camera.
04:07First thing, they're cold and purplish-blue.
04:12But slowly, as they warm up, a golden glow spreads through their bodies.
04:18And eventually, after half an hour or so, they become as hot as the rocks beneath them.
04:25Once they're thoroughly warmed up, marine iguanas can maintain their body temperature just about as constantly as I can,
04:33and what's more, at about the same level, or indeed slightly higher, around 37 degrees centigrade.
04:42Now they need to feed.
04:44There's nothing to eat on or around these barren rocks except seaweed, and to get that, they'll have to swim.
04:52But the sea around here is surprisingly cold, around 15 to 16 degrees centigrade,
05:00and only the bigger iguanas can absorb enough heat to power the dives to enable them to go to the seaweed at any depth.
05:13However, their bodies are now thoroughly warmed up.
05:17The thermal camera shows them as golden-yellow as they clamber down over the cold blue rocks and dive into the sea.
05:27Although their islands lie almost exactly on the equator,
05:31the sea here is permanently chilled by a cold current that sweeps up from the depths of the ocean,
05:38so they won't be able to stay in the water for long.
05:42The sea here is almost as cold as it is on the other side of the equator,
05:47The sea here is permanently chilled by a cold current that sweeps up from the depths of the ocean,
05:54so they won't be able to stay in the water for very long.
05:57They have no time to waste.
06:01In the shallows, close to the shore, the seaweed has been heavily cropped.
06:06To get a good meal, they may have to dive to at least 15 feet, 5 meters.
06:13They're able to reduce the chilling effect of the cold water
06:17by closing down the blood supply to their limbs and the outer part of their bodies.
06:22But even so, their body temperature may drop by 10 degrees or so.
06:27A cooling like that would kill a human diver.
06:34After 5 to 10 minutes on the seafloor, most iguanas have had enough
06:39and they return to the surface and the life-saving warmth of the rocky shore.
06:50A recently emerged iguana is black. It's chilled to the bone.
07:01Now they need heat in order to be able to digest that meal of seaweed
07:06and they get that by spread-eagling themselves on these black, hot, sun-baked rocks.
07:16Their image warms from black to purple
07:23and then from red to orange.
07:29In the evening, the temperature falls
07:31and they huddle together to retain their warmth as long as possible.
07:37They will have to wait until the following morning
07:40before they can re-warm themselves sufficiently to feed again.
07:48Most kinds of lizards have this daily schedule.
07:51Side-blotched lizards in California certainly do.
07:55You can see from the colour of my face that my body is warm.
08:00That's because I've got a central heating system
08:03which I've fuelled with my breakfast.
08:05In fact, about 80% of what I eat
08:08is used in keeping my body temperature high and steady.
08:13These lizards, however, squander very little of the energy
08:16they get from their food on warming themselves.
08:19They, like the marine iguanas, get nearly all they need for that
08:23by basking on the warm rocks.
08:26And so important is the need for warmth
08:30that the females actually choose their males
08:33on the basis of which has the best underfloor heating.
08:40Each male sits on his pile of boulders doing press-ups
08:44to signal his ownership and to warn off other males.
08:49Intruders are confronted immediately and, if necessary, attacked.
08:54And the victor returns to sit on his wonderfully warm throne.
09:05Look at his rocky kingdom with a thermal camera.
09:08He's got a nice, warm, warm place.
09:11He's got a nice, warm, warm place.
09:14He's got a nice, warm, warm place.
09:17He's got a nice, warm, warm place.
09:19He's got a nice, warm, warm place.
09:21Look at his rocky kingdom with a thermal camera
09:24and it's immediately clear why it's so precious.
09:27The rocks are very much hotter than the surrounding grassland
09:30and big, tall ones catch the sun earlier and retain its heat longer.
09:36So not only does the sun warm him from above, his rocks do from beneath.
09:42The most powerful, dominant male has, naturally, the best pile of rocks.
09:47And, not surprisingly, almost all the females.
09:57But is it the males themselves or their assets
10:00that the females are interested in?
10:03To find out, let's move their hot rocks
10:06and give them to a subordinate male.
10:18And the females quickly recognise
10:20that a more desirable residence has appeared in the neighbourhood
10:24and start to move across.
10:30And the sex-starved wimp suddenly finds himself amazingly popular.
10:39So the females do, indeed, go for the male.
10:43So the females do, indeed, go for the males with the hottest rocks.
10:53These lizards, on a small island off the shores of Menorca in the Mediterranean,
10:58get their heat from another and very unusual source.
11:04Ow!
11:07Sorry.
11:09They're very curious. I'm the new boy on the block,
11:13the new object in their environment.
11:17And that one just gave me a little nip.
11:22They investigate the world around them by tasting it
11:25and they're still trying to work out what I am.
11:33Their island is rocky and not particularly rich in food.
11:37The lizards are primarily insect eaters,
11:39but during the flowering season they also take nectar.
11:42They collect it from plants like spurge, which is very common.
11:46And they have a very special relationship with this flower.
11:51It's called the dead horse arum
11:54and it certainly looks like carrion and...
11:59..it smells very strongly of carrion.
12:02As a consequence of both its looks and its smell,
12:05it attracts carrion flies.
12:08And, of course, it's the flies that the lizards are after.
12:13But as well as providing food for the lizards,
12:17this extraordinary flower helps them in another way.
12:21If this central part, which is called the spadix,
12:26is slightly warm, as you can see from a thermal camera.
12:32The chemical process that produces the disgusting smell
12:35also creates heat and raises the temperature of the flower
12:39by up to five degrees above the surroundings,
12:42sufficiently high for a lizard to warm itself on it on a cold morning.
12:46And in case you find that hard to believe,
12:49here is confirmation from the thermal camera.
12:52The purplish-blue lizard
12:54quickly takes on the same temperature and colour as the arum.
13:02And sitting on arums brings another benefit.
13:09Breakfast.
13:11A fly, lured by the smell, crawls inside.
13:18The lizard hears the fly buzzing within.
13:23The fly, of course, can't find anything it wants,
13:26but now it can't get out.
13:28The entrance to the flower is blocked by the lizard.
13:41And the lizard gets an easy meal.
13:52Two months later, the arum flowers have shriveled
13:55and produced their fruits.
13:59Until 20 years ago, the lizards ignored these withered bundles.
14:03After all, they hardly looked like food.
14:06But then a particularly inquisitive individual sampled a fruit
14:10and found the soft flesh around the seed rather good.
14:14The habit spread, and now the whole lizard population,
14:17uniquely in the Mediterranean, have become arum fruit eaters.
14:22They do take a bit of swallowing,
14:24but the seeds passing through a lizard's gut
14:27not only survive, but germinate even more easily.
14:31As a result, the arums, which were rather scarce here 20 years ago,
14:35have suddenly become abundant all over the island.
14:39A cold, wind-stripped island off the coast of South Africa
14:43is not a place to be if you're not looking for a local man
14:47to feed a herd of birds.
14:49You don't have that in the military,
14:51you don't have that in the city.
14:53You don't have that in the village either.
14:55You don't have that in the town.
14:57You don't have that in the town.
14:59You don't have that in the city either.
15:01You don't have that in the town either.
15:03I mean, you don't really get a lot of work done here.
15:06the coast of South Africa, is not the first place you'd go to
15:10if you were looking for reptiles.
15:13But here on Dassen Island, among penguins and seagulls,
15:18there's one of the greatest concentration of tortoises
15:21to be found anywhere on Earth.
15:25There are about 5,000 of them on this one tiny island.
15:29The penguins and other birds, thanks to their warm blood,
15:33are active no matter how cold it is.
15:35But the tortoises have to wait for the day to warm up
15:38before they can get about their business.
15:47They bask in the sunshine, powering up their bodies
15:50to the optimum working temperature of 33 degrees centigrade,
15:54and then, as the sun sets, they go back to their nests.
15:58And then they go off to feed.
16:16As the day progresses, the temperature rises quickly,
16:19and even before noon, it's too hot for comfort.
16:23The tortoises have to head for shade.
16:28In the late afternoon, it gets cooler and the tortoises venture out again.
16:33For them, this is the best time.
16:36They're thoroughly warmed up, they've digested their morning meal,
16:40and they've got energy to spare.
16:47The tortoises are ready to go back to their nests.
16:50They've got plenty of food to eat,
16:52and they've got plenty of water to drink.
16:55The males begin to fight,
16:58jousting like medieval knights,
17:01using a projection on the front of the shell like a lance.
17:10The technique is to get the spike under your opponent
17:13and then flick him over onto his back.
17:18The males are not afraid of the tortoises.
17:21They flick him over onto his back.
17:28Contests can last for half an hour.
17:51The winner keeps biting his legs.
18:05The loser tries to right himself, but the winner keeps biting his legs.
18:22At last, the victor loses interest
18:24and goes off to find the female who caused the argument in the first place.
18:29As for the loser, if he doesn't manage to right himself soon,
18:33he may cook in the sun.
18:44Tortoises are able to sunbathe out in the open
18:47because their strong bony shell gives them plenty of shade.
18:50And their thin shell gives them almost complete protection from predators.
18:58Less well-armoured reptiles, like lizards, are vulnerable, of course,
19:03to hawks and coyotes and foxes and cats.
19:08And in the morning, when those warm-blooded animals are already active,
19:13the lizards are cold and can't move fast,
19:16so they have a problem.
19:18But they also have a solution.
19:21Secret sunbathing.
19:25You really can't see them until you're right on top of them.
19:31And there's one there.
19:34I'm in Arizona, and that, at my feet,
19:38is a lizard buried in the sand up to its neck.
19:44Even while it's buried, it can use the sunshine to warm its whole body.
19:48It can control the supply of blood to its head
19:51so that it pools in a cavity behind the eye.
19:55Soon, the blood there is as much as five degrees
19:58above the temperature of the rest of its body.
20:01Then the animal opens the major blood vessels in its neck
20:04and the hot blood circulates so that its whole body is thoroughly warmed,
20:09even though it's still mostly below ground.
20:19This is a horned lizard.
20:24And very beautiful, too.
20:26This particular species is called the regal horned lizard
20:30because it has this splendid crown of spikes at the back of its neck.
20:35When he's hidden, they break up the outline of his head
20:38and so you hardly see him at all.
20:41And now, in the warmth of my hand and in the sunshine,
20:44I guess he's warmed up quite a lot.
20:47Quite a lot.
20:48And if I put him down, he now, at last, may be able to run for it.
20:54And indeed he does.
21:05South African armadillo lizards, which live on these rocky outcrops,
21:09have a different solution to the problem of safe sunbathing.
21:14They've turned it into a social activity.
21:20Whole families of them live together in the crevices among the rocks
21:23and in the morning they all emerge to warm up in the sun.
21:29Of course, there is safety in numbers.
21:34There are lots of eyes to spot danger, if it appears.
21:44And when one sunbather takes fright, they all dive for safety.
21:50If a predator is quick, it is possible to grab one.
21:54But even then, an armadillo lizard is not going to be an easy meal.
21:59They have an additional form of defence.
22:03They bite their tails.
22:05The reason they do that is because their tails are very sharp.
22:11The reason they do that is that it covers up their vulnerable underside
22:19and exposes only these very sharp, spiny scales,
22:24which is very good protection against predators like snakes or mongooses.
22:30And they stay like this for quite a long time
22:34before they're confident enough to uncurl.
22:37I'll put him down and see how he does.
22:41Sunset necessarily brings an end to activity for most reptiles.
22:49But not for oar.
22:52A leopard gecko.
22:54It, like most geckos, is nocturnal
22:56and it manages to get all the heat it needs to survive in the wild.
23:01But it's not the only gecko.
23:03There are other geckos as well.
23:06It, like most geckos, is nocturnal
23:08and it manages to get all the heat it needs from the rocks,
23:11which retain something of their warmth for several hours after the sun has set.
23:18This male is in search of a mate.
23:21She is less brightly coloured.
23:28They inspect one another.
23:31He collects her scent with his tongue
23:33and discovers that not only is she female, but she's sexually available.
23:45He's interested.
23:51He nibbles her neck and strokes her flanks,
23:54all part of his elaborate courtship routine.
24:01Copulation begins.
24:07This is the time in mammals and birds when the sex of the young is determined,
24:12but not in a number of reptiles, including geckos.
24:16Once again, it's temperature that profoundly influences their lives.
24:23The female is a male.
24:25The female goes away to lay her eggs.
24:30She has chosen a place where the temperature is about 31 degrees.
24:35As her body is the same temperature as her environment,
24:38she can't heat her eggs by sitting on them as warm-blooded birds do,
24:42so they're exactly the same temperature as the rocks beneath.
24:48After a couple of months, both eggs begin to hatch.
24:52The first to emerge is a male.
25:05And the second will be, too.
25:07It's the temperature which has determined that.
25:10If it had been a few degrees lower,
25:12both eggs would have developed in the same temperature.
25:16It's the temperature which has determined that.
25:19If it had been a few degrees lower,
25:21both eggs would have developed into females.
25:34Crocodiles have their sex determined by temperature in a similar way.
25:39This clutch belongs to the Indian fish-eating crocodile, the gharial.
25:47The female has heard the calls from below ground made by her hatching young
25:52and is helping them to dig their way out of the sand.
26:06They immediately make their way down to the water.
26:17And mother goes, too.
26:34Here, of course, they are nice and warm.
26:37Water retains its daytime heat better and longer than rock,
26:41so unlike many other reptiles,
26:43gharials and other crocodilians have enough energy to feed actively all night.
27:14While being nocturnal is unusual among reptiles,
27:18it's the norm for amphibians.
27:21Their skin is not scaly and watertight like a reptile's.
27:25It's soft, moist and permeable.
27:28If they exposed themselves to sunlight for any length of time,
27:32they would dry out and die.
27:34So most frogs only leave their shelters at night.
27:44Since they can't absorb sunshine directly,
27:47they either get their heat from their surroundings
27:50or draw their energy from the fat reserves that they built up when the feeding was good.
27:55But even so, they seldom hop unless they have very good reason to do so.
28:02This frog, however, the South American waxy monkey frog, is exceptional.
28:08It's one of the few that can tolerate direct sunshine for any length of time.
28:15And that is because it secretes a wax from glands on its neck.
28:21No human sunbather goes to more trouble than they do
28:25to make quite sure that every part of their skin is properly anointed.
28:35The sun is a very important part of the human body.
28:39It's the most important part of the human body.
28:42It's the most important part of the body.
28:45It's the most important part of the body.
28:48It's the most important part of the body.
29:11The sunshine may also bring them an extra benefit.
29:15It probably protects them from the fungal infections
29:18to which many moist-skinned amphibians are prone.
29:29In the rainforests of Central America, the air is heavy with moisture.
29:34So the poison arrow frogs can risk basking in the little patches of sunshine
29:39that dapple the forest floor.
29:41And if they begin to dry out, they can retreat into the leaf litter.
29:49The sunshine gives them sufficient energy
29:51to permit the extravagance of calling almost continuously
29:55in defence of their territories.
30:01They even have enough spare energy
30:03to indulge in long battles with their neighbours.
30:11The sun is a very important part of the human body.
30:15It's the most important part of the human body.
30:18It's the most important part of the human body.
30:22It's the most important part of the human body.
30:42These fights can go on for well over half an hour at a time
30:46until both contestants are completely exhausted.
30:58So a moist skin limits the ability of the amphibian to fight.
31:04It's the most important part of the human body.
31:11It limits not only where amphibians can live,
31:14but how energetic they can be.
31:17Out in the sunshine, dry-skinned reptiles have more options.
31:23By collecting solar power so efficiently,
31:26reptiles need to use very little of the energy they generate themselves
31:31to warm their bodies.
31:33In fact, they use around a tenth
31:35compared with a mammal of a similar size.
31:38That means they don't have to eat very often.
31:42A puff adder, like this one,
31:44can wait almost indefinitely for its next meal.
31:48Amongst predators, patience really is a virtue.
31:57Whilst waiting for a meal to wander within striking distance,
32:01a snake shuts down its body processes
32:04so that it uses the minimum amount of energy.
32:07Only the equivalent of a pilot light is left on.
32:11And it can remain like this for weeks.
32:16All around it, mammals are expending their energy
32:19in a way that, compared with the snake, seems extraordinarily extravagant.
32:38But when a snake needs to move fast, it can do so with lightning speed.
32:52Once its prey is secured, a snake can take its time over its meal.
32:59This gigantic python is feeding on a deer.
33:04A python kills its prey by wrapping its coils around it
33:08and squeezing its victim so tightly and for so long
33:11that it can no longer breathe.
33:14But swallowing its meal takes time.
33:18The deer will go down head first.
33:21It's much easier that way.
33:24The ligaments connecting the snake's upper and lower jaw are elastic
33:29so that it can engulf the deer's head even though it is much bigger than its own.
33:35With its mouth stretched tightly around its meal,
33:38the snake can't breathe in a normal way.
33:41But it's able to push the top of its windpipe
33:44right out of its mouth and into its mouth.
33:48After a while, the python gets used to its new environment.
33:53It's going to start eating the deer.
33:56The deer is going to start dining with the python.
34:01The python is going to start eating the deer.
34:04The snake is going to start eating the deer.
34:06After some hours, all that can be seen of the deer are its hind legs.
34:33Once the meal has been completely swallowed, the inner workings of the snake's body change
34:39greatly.
34:42Its digestive processes switch to full power and increase their activity 40 times.
34:48There is an explosion of biochemical activity.
34:51The liver, the secretions of which power digestion, doubles in size within two days.
35:00The heart grows by some 40%.
35:07It will take the python at least a week to completely digest this enormous meal, but
35:13then it will not need to feed again for months or even a year.
35:21This ability to switch off helps reptiles and amphibians in another way.
35:28A baby North American painted turtle.
35:31It and the rest of its clutch have only just hatched.
35:36But it's late in the year and the chill of winter has already begun.
35:41If the hatchlings clambered out of their hole now, they would find nothing to eat, so they
35:46stay where they are.
35:54The temperature will fall to minus 10 degrees.
36:00Ice crystals grow around the babies and even inside their bodies, but their tissues are
36:06protected by a kind of antifreeze.
36:12This would kill any mammal or bird.
36:19They remain in this deep freeze for up to six months.
36:30But spring comes at last.
36:39The ice melts around them and eventually within them.
36:52Eventually they begin to come to life.
37:13It takes quite a time for them to become fully functional, but eventually they're ready
37:18to face the outside world.
37:33So by allowing their bodies to cool, they have avoided the hard times.
37:50With the arrival of spring, their parents are now preparing to breed again.
38:01The male courts the female by gently strumming her cheeks with his long claws.
38:12And she responds.
38:20Cold blood is clearly no barrier to affection.
38:24In fact, reptiles can conduct as complex and as sensitive a courtship as many a mammal.
38:38This is the biggest of all living reptiles and one of the most feared.
38:44If one creature were to be labelled a cold-blooded killer, it would be this, a saltwater crocodile,
38:50a monster that can grow to a length of 20 feet, six meters, and weigh a ton.
39:04But male and female, when they court, blow bubbles at one another.
39:16He is three times her size and could easily crush her, yet he treats her with great gentleness.
39:29He strokes her back.
39:43Finally, he aligns his body with hers.
40:14So union is achieved.
40:28Crocodiles are among the most ancient of reptiles.
40:32Their ancestors appeared at about the same time as the dinosaurs.
40:36But what about them?
40:38Were dinosaurs similarly cold-blooded?
40:43The rocks of the North American West are particularly rich in dinosaur fossils.
40:50A hundred million years ago, this was a horizontal mudflat at the edge of the sea.
40:58And across it came an adult dinosaur with a smaller, younger one trotting alongside,
41:05leaving their footprints behind to be fossilized.
41:11They were iguanodons, a herd of them, together with some bird-footed dinosaurs.
41:18Were these all solar-powered?
41:23Some of the ancient reptiles had specific adaptations to help them collect heat.
41:29This is a plate from the back of a stegosaurus, and you can still see the lines where the
41:37blood vessels ran, which collected the heat and carried it to the rest of the body.
41:44So for the stegosaurus at least, the need to collect heat seems to have been just as
41:48important as it is for its relatives alive today.
41:53But there are clues that suggest that ancient reptiles were better at maintaining their
41:59temperature than their modern counterparts.
42:03This is the jawbone of a very large and very famous dinosaur.
42:12In life, its head would have been 18 feet, 6 meters, above ground.
42:20This is the jaw of Tyrannosaurus rex.
42:32An animal as big as this has a very large body mass, which retains heat very well.
42:38So perhaps these huge dinosaurs were, in fact, warm all the time, simply because they were
42:44too big to lose all their heat overnight, as a smaller reptile would.
42:51But what about when they were small?
42:53Were adolescent tyrannosaurs able to maintain a steady body temperature?
42:58Were they, in short, warm-blooded?
43:02Evidence on that can be found in the microscopic structure of their bones.
43:14This is the leg bone of a young Tyrannosaurus, and it has bands in it.
43:24The inner section, formed when the animal was young, has an open structure like the
43:29bone of a fast-growing warm-blooded mammal.
43:33The outer part is more dense, more like that of today's reptiles, but whether dinosaurs
43:40were really, truly warm-blooded, we may never know.
43:45What we do know, however, is that dinosaurs were extraordinarily successful and dominated
43:51the earth for 150 million years.
43:57But there are some reptiles today that can keep their body temperature well above that
44:01of their surroundings.
44:04And these are the tracks of one of them.
44:08These giants haul themselves up out of the sea along beaches like this in many parts
44:15of the tropics.
44:16But in order not to disturb them, I'll turn this light out and we'll look for them with
44:21infrared cameras.
44:28Leatherback turtles.
44:31Like crocodiles, turtles are very ancient creatures, having first appeared at about
44:36the same time as the early dinosaurs.
44:39Today, leatherbacks are the biggest of all reptiles and the most widely distributed,
44:46for they're found all the way from these warm tropical waters to the freezing seas
44:50of the Arctic.
44:59These have come ashore on a beach in Trinidad, where almost certainly they were hatched.
45:04Now they, in their turn, are laying their eggs here.
45:15Leatherbacks, we know, can generate heat internally, and there is proof of that if you have a look
45:24at her eggs that she's laying right now on that thermal camera.
45:29They are emerging from her body, and lo and behold, they are bright yellow verging on
45:37white, proving that they are warmer than their surroundings.
45:44And she generates that heat within her body from special deposits of fat, so that she
45:50can maintain her internal body temperature up to eight degrees centigrade above that
45:55of the water through which she swims.
46:00As she sweeps away the surface sand, you can see that the sand too is yellower, warmer
46:05than the outside of her shell, for it still retains the heat it acquired during the day.
46:18So how do leatherbacks retain that precious and expensive internally generated heat?
46:25Well, to start with, they have their huge size to help them.
46:30They really are massive animals.
46:32This one is getting on to two meters, six feet long, and they can grow to weigh a ton
46:38and a half.
46:39And, of course, big objects retain their heat very much more readily than small ones do.
46:46And there's another reason how I am bright yellow going into white, which shows that
46:54I'm losing a great deal of my heat.
46:57She, on the other hand, is very much darker, and that is because she has an internal layer
47:05of fat, an insulating layer, just beneath the shell, which wraps around her body.
47:13The leatherbacks are the only reptiles in the world to have this kind of insulation.
47:28Her eggs laid, she fills in the hole with sand.
47:34And now she's on her way back to the sea.
47:41Life in Coldblood has been a great success.
47:44It has, after all, endured for some 350 million years.
47:50But how did it all begin?
47:53To find the answer to that, we have to go back in time, and back to the water, to the
47:58age when strange fish were hauling themselves up onto the land, fish that were the ancestors
48:05of the amphibians.
48:07Amphibians and reptiles are not easy creatures to film.
48:26They certainly do interesting things, but they also spend a great deal of time doing
48:31nothing much.
48:35We needed the help of scientists who really understood these creatures.
48:42Some workers have spent over 20 years studying their animals, both in the lab and in the
48:47field.
48:48They investigate the lives of their chosen species using all kinds of gear.
48:54Some sophisticated, some perhaps less so.
49:06With their help, we had a rare chance to get under the skin of some of our subjects.
49:21Madagascar was going to be a very important location for us.
49:27It's a huge island, a thousand miles long, with a great variety of habitats, and it's
49:32extraordinarily rich in reptiles.
49:40I first went to Madagascar back in 1960, filming for a series called Zoo Quest.
49:50Back then, I was trying to film all kinds of creatures, including the monkey-like lemurs
49:56and many rare birds, but I was particularly fascinated by the island's chameleons.
50:05There are, in fact, more species of chameleons in Madagascar than in all the rest of the
50:10world put together.
50:16There is one, the pygmy leaf chameleon, which was said to be only an inch or so long.
50:21I yearned to see it, but I never found it.
50:27Now I was back, and this time reptiles were our sole subject.
50:36Although Madagascar is only separated from the east coast of Africa by 300 miles of sea,
50:42its people, and particularly its animals, are very different indeed from those on the
50:46continent, with hundreds of species that are found nowhere else in the world.
50:53Once again, I was in search of chameleons.
50:57Then, all television was black and white, but now I could film and record chameleons
51:04in colour, and what colours they have.
51:26We had come in the rainy season, when most creatures, including reptiles, tend to breed
51:32and are therefore particularly active and interesting.
51:36And this time, I had the help of Bertrand Razahamatrach, a Malagasy naturalist who's
51:42made a particular study of chameleons.
51:45He's worked on them for over ten years and knows most kinds very well.
51:49I asked him about the pygmy species that had fascinated me for so long.
51:54So I mean that really is full grown?
51:57Yes, full grown.
51:59But then it's only that big?
52:01Yeah, it's very small.
52:06He suggested that although chameleons are mostly active during the day, we should look
52:11for them at night, because most of them turn pale in the dark and are therefore easily
52:17picked out in the light of our torches.
52:22Ah!
52:29What is that?
52:30This is...
52:31What species?
52:32This is Oostelet.
52:33Oostelet, aye, aye.
52:34And male or female?
52:35Female.
52:36How do you know?
52:37The colour.
52:38There's another?
52:39Oh, there's another.
52:46This one was far from upset at being woken up.
52:51Ah!
52:55It's fed!
52:57That's absolutely extraordinary.
52:59It can't possibly feed normally in the darkness.
53:04It just takes advantage of our light and finds an insect.
53:07Bravo.
53:08Well, let's go and see if we can find more.
53:13Bertrand explained that there was another reason why night was the best time to look
53:17for chameleons.
53:19When they go to sleep, they climb to the very far end of branches, where they're out of
53:24the way of predators such as snakes.
53:26There's another.
53:27And, of course, that was where we found them.
53:31Just as he said.
53:44Oh, that's a big one.
53:49Beautiful.
53:56This one is just a baby.
53:59And how old do you think that is?
54:02I think just a few days.
54:03A few days?
54:06So, even when it's nearly hatched, it knows to come to the end of the branch?
54:13Yes.
54:14Yeah.
54:15Look.
54:16It knows the tip of a branch.
54:18Yes.
54:19Yeah.
54:20Well, very difficult to get.
54:21Yeah.
54:22Of course, if it was in the day, a bird could get it.
54:25Yeah.
54:26But at night?
54:27At night, it's safe.
54:29Back in 1960, my chameleon hunting techniques weren't quite so expert.
54:36However, I did discover that if you put a stick in front of a chameleon,
54:42it will usually obligingly walk onto it.
54:56But now, with Bertrand as my guide, we could search for the wonderful species
55:02that I'd failed to find before.
55:04Would they be down here?
55:08It lives on the ground, almost invisible among the leaf litter.
55:14That?
55:15Yes.
55:16But Bertrand spotted it.
55:24How extraordinary.
55:27This is a pygmy leaf chameleon.
55:30The smallest chameleon in the world.
55:33In the world?
55:34Yeah.
55:35And probably the smallest reptiles in the world.
55:39Of any kind?
55:40Mm-hmm.
55:41You know, I'd heard about these, and I was here in Madagascar,
55:49You know, I'd heard about these, and I was here in Madagascar,
55:5747 years ago, and I read about these, and I never saw one.
56:07And I think it was because I never knew they were as small as this.
56:15That is absolutely extraordinary.
56:18It's about the size of a blue bottle, a blowfly.
56:25And what does it feed on?
56:28Small flies.
56:29Small flies.
56:31How absolutely wonderful.
56:38I am astonished.
56:41That is the most marvelous thing I've seen for a very, very long time.
56:48Finding the pygmy chameleon would not have been possible
56:51without Bertrand's expertise and sharp eyes.
56:54He's just one of the scientists who has helped to reveal to us
56:58the secret lives of reptiles and amphibians.
57:18In memory of Bertrand
57:23In memory of Bertrand
57:28In memory of Bertrand
57:33In memory of Bertrand