- 4 months ago
see more on:
https://realtv.mytvchannel.org/index.html
https://realtv.mytvchannel.org/index.html
Category
📚
LearningTranscript
00:00Satsang with Mooji
00:30A strangely shaped mountain catching the clouds high above the jungles of Venezuela.
01:00Its summit rocks have been carved into a multitude of grotesque shapes.
01:06The sculptor, an agent that is continuously at work on much of the landscape of our planet, rainwater.
01:15It washes over the rock, eroding it chemically.
01:19It permeates the cracks, freezes and chips it off in flakes and splinters.
01:28As the water flows downwards, it starts on a long journey that will take it from the rain-drenched mountains to the sea.
01:35And here, with a leap of over 3,000 feet, the highest made by any river, it forms the Angel Falls.
01:42Our journey begins not far from that towering waterfall, on the high moorlands of Peru, 15,000 feet above the sea.
01:4915,000 feet above the sea.
01:56Water is a very extraordinary and very precious substance.
02:03It's the only substance on Earth, apart from Mercury, which remains liquid at normal temperatures and pressures.
02:10And because of that, it's an essential part of the bodies of all living organisms, animals and plants.
02:17Without it, life would come to an end.
02:20And this particular water is a very rare kind.
02:3097% of the water on Earth is salty, the sea.
02:35But this was distilled from the surface of the sea by the heat of the sun, rose into the sky as vapour, condensed to form clouds, and then fell again as rain and snow to form streams of pure, fresh, sweet water.
03:02But this particular stream is on its way to the sea, a very long way away, because these are the Andes.
03:12And this is one of the many streams that can claim to be a source of the biggest river on Earth, the Amazon.
03:23The difficulties of living in this young and violent river are formidable.
03:28Its waters are thick with powdered rock and mud, but as yet they have gathered few nutrients, and they rush down the valley at tremendous speed.
03:37Anything that lives here has to be a prodigious swimmer.
03:41And these are their torrent guts.
03:44They exploit the swirls and eddies with consummate skill, paddling with powerful strokes of their large webbed feet.
04:04They head always upstream, bracing themselves against the rocks with their stiff quilled tail, and using small, horny spurs on the wrists of their wings to give them purchase.
04:19A pair owns a stretch of the river, working their way up it until they reach the frontier of their territory, when they abandon themselves to the flood and are swept downstream to begin all over again.
04:36Anchored firmly to the rocks is a kind of moss.
04:53Mosses are primitive ancient plants that appeared on Earth long before flowering plants.
04:59And this torrent moss is found in young rivers and streams all over the world.
05:04And wherever it grows, whether in the Andes or here in Europe, it provides shelter for a multitude of insect larvae.
05:12In summer, these creatures will become transformed and fly briefly above the river to mate, but most of their lives are spent underwater.
05:22Some are streamlined against the current.
05:25The caddisfly larvae live in protective tubes, the hollow stem of a reed, or a construction of bits of wood stuck together with silk.
05:34Some weight themselves down so that the current doesn't shift them by building their shelters from heavy grains of sand.
05:49The larva of the blackfly holds onto a pebble with its back end, while it grabs at food particles that are swept past it with the antennae on its head.
05:59It grips the rock with a ring of hooks, but even if it loses its hold, all is not lost.
06:09It has a lifeline of silk, which it has attached to its chosen pebble.
06:16Having hauled itself back, it now has to get a new grip.
06:33First, it spins a tiny pad of silk from a spinneret just beneath its mouth.
06:38Then it fixes its hooks into that.
06:41The nets with which it collects its food are modified antennae.
06:47And the larva brushes off what they catch with alternate flicks of its mouth parts.
06:56Not all caddis larvae live in solid tubes.
06:59This one builds a construction that serves both as a home and a food gathering device.
07:04It uses its silk to produce a funnel-shaped scaffold of criss-crossing threads.
07:15Undulating its body is a way of aiding its breathing,
07:29for the movement speeds the flow of oxygen-bearing water through the funnel.
07:33It holds on with the hooks at the back,
07:38leaving its jaws and front legs free to do the construction work.
07:45These are the blackfly large springs.
07:47The blackflyisser's BACK
07:49The blackflyises are free to do the construction work.
07:52This blackfly larva wasn't saved by its lifeline.
08:22But the caddisfly larva itself, ferocious and artful trapper though it is, is also at risk.
08:52The dipper relishes it.
08:58Dippers live both in the rivers of North America and Europe.
09:03Underwater their swimming technique is quite different from the torrent ducks in the Andes.
09:09Its feet are not webbed like a duck's, so it propels itself with its wings, flying underwater.
09:15In similar cold, fast-flowing streams in North America lives a kind of giant newt, the hellbender.
09:26When it's young, it also, like a dipper, takes insect larvae.
09:32But it can grow to over two feet long and then it seeks much bigger prey.
09:40A crayfish would suit it admirably.
09:46A nanow escape, the crayfish saved itself at the last moment by a convulsive snap of its tail, but the hellbender doesn't give up easily.
10:03Both animals try to keep out of the current and habitually creep into crevices.
10:24But that, sometimes, is a mistake.
10:54Small streams that tumble down the sides of the valleys and feed young rivers have their own population.
11:02In Malaysia, the big-headed turtle clambers around the waterfalls, using its tail as a prop.
11:19In West African waterfalls, and nowhere else, lives the extraordinary hairy frog.
11:28Its so-called hairs are filaments of skin on its flanks, which act as gills, helping it to absorb oxygen from the water.
11:38And, almost as unusual, it has claws that help it grip the slippery stones.
11:47The many sources of the Amazon began as numberless rivulets on the eastern flanks of the Andes.
12:06Now, 5,000 feet lower down, each has grown beyond recognition and cut its own zigzag valley.
12:13White water, tumbling down the valley wall, joins the brown water of a larger tributary, heavy with mud and sediment.
12:22And as it gets bigger and bigger, so it becomes more and more powerful.
12:32It's the dry season at the moment, and the river is comparatively low.
12:37But during the rains, when it's in space, its waters rise up over here, and the sheer volume and weight and force of them can shift boulders the size of these.
12:50The volume and speed of its waters are not the river's only weapons.
13:10It also has teeth, and in this empty, rainy season part of its bed, you can see them.
13:19Sand and gravel, fragments of rock that have been eroded from higher up in its course,
13:29and which the river hurls with enormous force at the rocks of its riverbed.
13:39With such tools, it can carve away the sides of mountains.
13:49Young, vigorous rivers transform the land, demolishing the mountains, breaking down the debris into smaller and smaller particles, and carrying them away downstream.
14:07This river, in China, is perpetually so turbid that it's called the Huanghou, the Yellow River.
14:14It carries a bigger load of sediment than any other river in the world.
14:18During floods, each cubic yard of water contains over 2,000 pounds of soil and pulverised rock.
14:25Rivers, in the full vigour of their youth, are terrifyingly strong.
14:43They roll great boulders along their beds.
14:46They cut away at the banks, undermining trees which crash into the waters and are swept away.
14:52When a river encounters a band of unusually hard rock, such as an ancient flow of basalt lava, its progress is temporarily slowed.
15:09It spreads out across the barrier and then tumbles over the front edge.
15:14So are formed some of the loveliest cascades.
15:18These are the falls of Iguazu, on the border of Brazil and Paraguay.
15:23They can't compare in height with the Angel Falls, but in terms of the volume of water that passes over them, they are incomparably bigger.
15:31The falling waters pound away at the base of the falls, undercutting the basalt until blocks split off the face.
15:51So the falls steadily work their way upriver, leaving downstream a deep gorge.
15:57And animals live even here, within the falls themselves.
16:04Swifts herch on the rock face, behind the cascade.
16:09Every evening, they congregate high above Iguazu.
16:12After a day of hawking for insects, they're ready to roost.
16:16And where safer than behind a screen of falling water?
16:20Some dive down with such speed that they shoot right through the fall.
16:27And now the river has left the mountains far behind and has changed its character considerably.
16:35It's bigger, it's broader, and its waters carry not only sand and gravel, but rich nutrients that have washed in from its vegetation-covered banks.
16:57And after it's gone over its last rapids and tumbled over its last fall, it becomes a very different river indeed.
17:07It's middle-aged, ampler, less violent, more sluggish, and richer.
17:23On the banks of the Amazon tributaries, the jungle stands thick.
17:28Birds like the sun-bitten stalk quietly in search of a meal.
17:33Huge fish cruise through the slow waters.
17:38The arapaima, one of the largest of freshwater fish, grows over six feet long.
17:46The Amazon contains over 3,000 different kinds of fish.
17:50That's more than live in all the Atlantic.
17:57Rays almost certainly evolved in the sea.
18:00But this species has managed to make the change to freshwater and lives high up the Amazon.
18:06Many other fish have evolved here in freshwater and have become suited to all its variations of depth, speed, and chemical composition.
18:16To muddy water and to clear.
18:18To stretches that are thick with plants and places where there are none.
18:22Their variety is enormous.
18:27Take, for example, just one family, the catfish.
18:31They're all bottom-dwelling fish with feelers or barbels on their snouts that have sense organs on them.
18:37So the fish can feel and taste their way through the thick muddy water or at night.
18:43There are small ones and immense ones.
18:46Some that give electric shocks and others that swim upside down.
18:50Those that live in fast-flowing waters have suckers on their chins or undersides with which they cling to rocks.
18:58In South America alone, there are 1,200 different species of catfish.
19:051,200 different species of catfish.
19:081,200 different species of catfish.
19:121,200 different species of catfish.
19:131,200 different species of catfish.
19:141,200 different species of catfish.
19:151,200 different species of catfish.
19:161,200 different species of catfish.
19:171,200 different species of catfish.
19:181,200 different species of catfish.
19:191,200 different species of catfish.
19:201,200 different species of catfish.
19:211,200 different species of catfish.
19:221,200 different species of catfish.
19:231,200 different species of catfish.
19:241,200 different species of catfish.
19:251,200 different species of catfish.
19:261,200 different species of catfish.
19:271,200 different species of catfish.
19:281,200 different species of catfish.
19:301,200 different species of catfish.
19:32In these crowded waters,
19:34many fish give special protection to their young
19:37for the first few weeks of their lives.
19:40This fish, the discus, goes even further.
19:43It provides its fry with special food.
19:46The parents exude a nutritious slime from their skin
19:50and the young graze over their flanks, feeding on it.
20:04After a week, they're big enough to feed on small particles floating in the water.
20:34These are now a month old
20:47and have already assumed the disc-like shape of their parents.
20:52They're becoming independent,
20:53but they've strayed past the lair of an electric eel.
20:59The eel has very poor eyesight,
21:02but it detects the presence of objects around it
21:04with short electric discharges, a kind of radar.
21:09It rises for a gulp of air.
21:11This time, the young discus seem to have escaped detection.
21:14But the eel can also produce a major electric shock,
21:26which stuns its prey.
21:28Astonishingly, it releases its capture.
21:46Perhaps so small a fish is not worth eating.
21:48And the young discus, apart from the marks of the eel's jaws on its flanks,
21:52seems no worse off.
21:53One Amazonian fish puts its eggs beyond the reach of any water-living predator,
22:00on leaves overhanging a river.
22:04A pair of splashing tetras are caught in.
22:09They curve their bodies and, for an instant, leap clear of the water.
22:13Sometimes, a third fish joins in.
22:23The bigger of the two is the male.
22:26For a moment, the pair hang on the leaf,
22:28supported by the suction of the male's floppy fins.
22:31Again and again, they jump.
22:38In this one moment, the female lays her eggs and drops off,
22:41and the male fertilises them and follows her.
22:44Each time, they leave behind a dozen or so eggs.
22:47A few infertile eggs drop off the leaf, but they're not wasted.
22:58Eventually, as many as 200 eggs are safely placed out of harm's way,
23:02and the river can be an exceedingly dangerous place.
23:07Piranha, the most savage of all the Amazon's fish.
23:11A swimming capybara suddenly realises their presence
23:14and tries to retreat, but it's too late.
23:22The splashing, the taste of blood spreading rapidly through the water,
23:26attracts more and more of the shoal,
23:28until there are hundreds of the fish,
23:30all possessed by a frenzy for flesh.
23:33None are much more than a foot long,
23:35but their teeth are sharp enough to cut clean through bone.
23:44Within minutes, there's little left.
23:53As the river gets older, it slows down.
23:56A minor obstacle in its path is now enough to deflect it.
24:00The water flowing round the outside of a bend
24:02has to travel farther and speeds up and cuts away at the bank.
24:05On the inside of the bend, where the current is slow,
24:09the water can no longer support its load of sediment
24:11and drops it to form a shoal.
24:13So the bend becomes more and more exaggerated
24:16as the elderly river swings from side to side
24:19in a series of loops and meanders.
24:22In places, one bend may approach another
24:24until the neck of land between the two is so narrow it collapses.
24:27Then the river takes the shorter course
24:30and the meander is left isolated as a curving lake.
24:34There, the water at last is still.
24:38Plants no longer have to fight against a current
24:40and the lakes become clogged with vegetation.
24:44These are the largest floating leaves of all,
24:48the leaves of the famous giant Amazon lily.
24:52Covering the water with leaves of this size
24:54is a very aggressive act,
24:56for it cuts out the light in the water below,
24:59making it very difficult for other plants to grow there.
25:02And the upturned rims of the great pads, as they grow,
25:05thrust to one side all other floating plants.
25:09And to prevent these leaves being destroyed
25:12by being eaten by fish,
25:14they are protected with very effective
25:16and ferocious spines underneath,
25:18as you can see most clearly on this half-open bud.
25:23It can develop from the size of a soup plate
25:25to a huge emerald disk six feet across in only a few days,
25:29growing at a rate of one square inch in a minute.
25:32The flowers develop with similar speed.
25:35Each opens first in the evening
25:37and remains with its petals spread and powerfully fragrant all night.
25:41By the morning, however, it's closed again.
25:44But during the night, it's taken prisoners.
25:48Inside the flower are beetles.
25:52Sometimes there are as many as 40 of them in a single bloom.
25:56And they're not there just by accident.
25:58They've been attracted by special sugary outgrowths in the centre of the flower.
26:03And while they're trapped in there during the day,
26:05they will feed on those.
26:07This evening, the flower will open for the second time,
26:10the beetles will be released,
26:12and they'll fly off carrying with them pollen
26:14to cross-pollinate another lily flower.
26:17And then, after just two nights,
26:20this bloom, by now turned purple,
26:24will crumple and die.
26:25The immense leaves, strengthened by air-filled ribs beneath,
26:33can support the weight of a small child.
26:36And water birds can walk over them
26:37with complete confidence and safety.
26:44This one, the jacana, has greatly elongated toes
26:47that can spread its weight so effectively
26:49that it can tread on very much flimsier leaves
26:51than those of the Amazon lily without submerging them.
26:54It seeks insects, and there are plenty to choose from.
26:58The pond skater sits on a leaf,
27:01but it could equally well sit on the water,
27:03for the surface forms a springy platform
27:05that supports many small creatures.
27:08Water molecules are bound to one another
27:09by a force akin to magnetism.
27:12They're not attracted to molecules of air above,
27:15so those on the surface have their forces concentrated sideways,
27:18giving the surface especially strong tension.
27:21And the pond skater hunts on it.
27:24It's lost its prey under the leaf.
27:31This time, there is no escape.
27:34The pond skater stabs its victim and sucks it dry.
27:38It's crucially important for the pond skater
27:40to keep meticulously clean.
27:42The wax's surface of its body
27:44and the fine hairs on its feet repel water,
27:46but any dirt on them that is wettable
27:48would break the surface tension film.
27:52They're aggressive insects,
27:54each with its own territory among the lily pads.
28:01Intruders are immediately chased away
28:03and fights between rivals are common.
28:10The surface tension film
28:11is not only the pond skater's platform,
28:14but their sounding board.
28:16Through sense organs on their feet,
28:18they can detect the vibrations
28:19caused by the struggles of an insect
28:21that has fallen on the surface.
28:22And by bouncing up and down,
28:24they communicate to one another,
28:26sending keep-out signals to rivals
28:28and come-hither signals to potential mates.
28:31Whirligig beetles use vibrations of the surface film
28:49in a slightly different way.
28:51By gyrating, they create ripples,
28:53and by monitoring the returning echoes,
28:55they detect the presence of other creatures
28:57and obstacles around them.
29:01They have excellent eyes,
29:05which are partitions
29:06so that the lower half peers downwards
29:08to see what's happening in the water beneath.
29:12Hanging from below the surface
29:14is another hunter.
29:16Its tail has two tubes
29:17which penetrate the surface film
29:19and collect air so that it can breathe.
29:22At its other end,
29:23its head has ferocious jaws
29:25with which it seizes its prey.
29:27This is the larva of the giant diving beetle
29:29and it's caught a tadpole.
29:31It has to come to the surface even when it's adult
29:35so that it can collect air
29:37to sustain it on its hunting forays
29:39down into deeper waters.
29:44The water boatman patrols the surface looking for prey,
29:48not from above like the pond skater,
29:50but from below.
29:51The two kinds of insects between them manage to collect most of the creatures
29:55that are trapped in the surface film.
29:58The camphor beetle lives on plants at the water's edge,
30:02but it is perhaps the most versatile of all water walkers.
30:05It can run over water like a pond skater.
30:10It can also produce a substance which, like camphor,
30:14greatly reduces the tension between water molecules.
30:17In emergencies, it squirts this from its tail
30:19and with the tension reduced at the back end
30:21but pulling hard at the front,
30:23it shoots across the surface so fast
30:25that the only way to see it clearly is in slow motion.
30:28And as a final demonstration of its versatility,
30:35it can, like most good beetles, fly.
30:41One particularly ferocious hunter
30:43lives on the edge of lakes and ponds in Europe,
30:46the fishing spider.
30:49It uses the surface tension film
30:51in the same way as other spiders use their webs.
30:55With its front legs resting delicately on the surface,
30:57it feels for tell-tale vibrations.
31:04But it also has excellent sight
31:06and can see potential prey below the surface.
31:12The stickleback sees only the spider's feet.
31:15That is a greatly slowed-down version of the kill.
31:28In reality, the pounce is rapier swift
31:31and the stickleback had little chance
31:33once it strayed within range.
31:35The lakes and ponds fed by streams
31:49or cut off from the main course of the river
32:03are comparatively small.
32:05But where the rivers flow into basins
32:07created by geological faults,
32:09their water accumulates in immense lakes.
32:12This is Lake Prespa in Yugoslavia,
32:15not the largest of lakes,
32:16but even so 20 miles long.
32:19As the rivers which feed it enter its still waters,
32:22they lose their impetus and drop their sediment.
32:24So such lakes are potentially very fertile
32:26and their animal inhabitants,
32:29no longer harassed by a perpetual current
32:31nor hemmed in by a shallow bottom or narrow banks,
32:34can proliferate, and they do.
32:37Fish swarm in their waters.
32:38And fish-eating birds like pelicans and cormorants
32:49swarm correspondingly.
32:51Land-based creatures haunt its margins.
33:11These may be its most fertile parts,
33:13for the lack of strong currents in a really deep lake
33:16can leave the bottom waters starved of oxygen.
33:18But in the shallows,
33:20especially when they are warmed by the summer sun,
33:23algae and other plants flourish,
33:25small invertebrates proliferate,
33:27and there's food for even the least agile of hunters.
33:48But in one way, these large lakes are very special.
33:59This trout, with distinctive red spots,
34:01lives in Lake Ochrid, a few miles away from Lake Prespa,
34:05but nowhere else in the world.
34:07Isolated in the lake,
34:09communities of fish become very inbred.
34:11Small characteristics that could be lost in bigger populations
34:14become fixed, and the fish evolve into new species.
34:19A similar thing has happened to the shrimps.
34:22And among the many different species of water snails,
34:33several are now unique to Lake Ochrid.
34:36In the heart of Russia lies a stretch of fresh water so huge and so ancient
34:47that these processes have produced new species
34:50on a scale unequalled anywhere else in the world.
34:54Lake Baikal.
34:55The lake lies in a great depression,
35:00formed by faulting in the Earth's crust.
35:03It's 400 miles long and 5,000 feet deep,
35:08the deepest of all lakes.
35:12In the depths of the lake, 1,000 feet down,
35:15lives a unique kind of salmon, the omel.
35:19In summer, they move up into the shallows
35:21and feed on caddisfly larvae and sandhoppers.
35:24And here they're caught in great numbers
35:26for their delicious eating.
35:38But this is only one of Baikal's special inhabitants.
35:43Of the 1,200 different kinds of fish and other animals
35:46and 500 plants that it contains,
35:49over 80% are unique.
35:51There are unique mollusks, unique flatworms
35:54and even one unique mammal, the Baikal seal.
36:02This tiny seal is almost certainly descended
36:05from the ringed seal of the Arctic Sea.
36:08Today, the lake is over 1,000 miles away from that sea.
36:11It's likely that the ancestors of these creatures
36:14arrived here during the Ice Age,
36:16when the journey may have been shorter and easier.
36:19Since then, cut off from other ringed seals,
36:23they've developed in their own way.
36:24The Amazon has no great lake on its course,
36:30so even in its middle stretches,
36:32it still carries mud from the Andes.
36:35The Rio Negro, which joins it here, is clear,
36:38for it has come from the northwest,
36:40where the rocks are hard and bare.
36:42The two immense rivers flow for miles alongside one another
36:46in the same bed, scarcely mixing.
36:48As well as sediment, they also carry abundant nutrients,
36:53and life on their banks flourishes as never before.
36:58Herds of capybara wade through the shallows,
37:01cropping the luxuriant plants.
37:03They're excellent swimmers, with webs between their toes,
37:13and they have that placing of eyes, ears and nostrils
37:16that's so valuable to mammals that regularly swim,
37:18on the top of the head,
37:20so that as the animal lies submerged,
37:22they can see, hear and smell
37:24what's going on above water around them.
37:26Giant otters have a similar head design,
37:43and sometimes lift themselves above the surface
37:46to get an even better view of their surroundings.
37:48This Amazonian species is the biggest of all the world's otters,
37:58six feet long, and a most powerful swimmer.
38:01It's well-equipped with large webbed feet,
38:03a flattened tail, and sensitive whiskers.
38:06A pair lays claim to a stretch of river
38:08by making territorial patches on the bank,
38:11marking them with their own personal smell.
38:18There are otters in many of the great rivers of the world,
38:28and they are the most graceful of swimmers.
38:46In India, they share the harvest of fish
38:48with the gavial.
38:51Most members of the crocodile family,
38:53when adult, feed largely on carrion,
38:55but the gavial eats only fish,
38:57and has long, narrow jaws,
38:59studded with abundant teeth,
39:01with which it catches them underwater.
39:06A host of birds also claim a share of the river fish.
39:09This is the hooded magansa,
39:11one of a group of ducks called sawbills.
39:18It's beak, like the gavial's jaws,
39:25is long and narrow,
39:26so it's the more easily snapped together underwater,
39:29and it also has a notched edge
39:31to give it a grip on the slippery fish.
39:33But their feathers trap so much air
39:39that the pair have to work very hard
39:41to get down to any depths.
39:44Coming up again is easy enough.
39:47But the meal is a mere mouthful,
39:49and the magansa must look for another one.
39:51And on the bottom lurks more danger for a fish.
39:59A worm, perhaps?
40:05No, the deceiving tongue of a turtle.
40:08A worm with a turtle in the middle.
40:31And in the sky above the river, more trouble for a fish.
40:52The kingfisher.
41:01And there's still one left for next time.
41:23The fish eagle is not a diver but a pouncer with a marvellously coordinated action.
41:31The aerial onslaught on the fish continues not only throughout the day but at night.
41:38An owl goes fishing in Africa.
41:46Its legs are bare. Feathers would drag in the water.
41:50And it has spines on the underside of its toes which give it a firm grasp on a fish.
42:01The fish ask for it.
42:04The fish will drag in its way to the lake.
42:06The fish can just stay in the water.
42:07The fish will drag in the water.
42:09The fish will drag in the water.
42:11The fish will drag it in the water.
42:12It has been swam canceled.
42:13While the fish will drag the fish, you can't see.
42:15In the last phase of their lives, these great rivers often flow out of control.
42:34Their tributaries, far away in the mountains, fed by the heavy storms of the rainy season,
42:39pour so much water into them that they burst their banks.
42:42The Amazon rises every year to flood tens of thousands of square miles of forest,
42:49in some parts as much as 40 feet deep.
42:58Some of these trees are flooded for eight to ten months every year.
43:03They need only a couple of months annually out of water for them to grow
43:06and for their seeds to germinate and sprout.
43:09But, we still don't know exactly how they manage it.
43:21As the floods well out over the land, fish from the river travel with them.
43:25This is going to be their best feeding time in the whole year.
43:34And so it is for other creatures too.
43:37Among the fallen tree leaves that carp at the bottom lies the Matamata turtle,
43:48marvellously camouflaged, waiting for a decent-sized fish.
43:51And there are plenty already here, sheltering like the turtle among the still unrotted leaves.
44:13Piranha are here too.
44:22These are not the flesh-eating kind.
44:24Their teeth are used for something different.
44:28Fruit.
44:29As the river becomes older and older, its riches increase still further.
44:51All over the world, as rivers approach their end, they begin to deposit the sand and mud
45:00that they've gathered from so far and carried for so long.
45:04In many parts of the world, reeds grow thickly on these shoals and banks,
45:09and their stems collect even more sediment as the river waters swirl through them.
45:13Living in these dense reed beds requires considerable skill.
45:18The little bittern, somehow or other, is able to find its nest hidden out of sight
45:23somewhere in this seemingly uniform stretch of reeds.
45:29It regurgitates from its crop ample supplies of fish and frogs for its young.
45:35Their world is an infinity of vertical stems, but they're nimble climbers from an early age,
45:53and they leave the nest within a few days of hatching.
46:05There they wait, almost invisible, for their parents to return with restocked crops.
46:10The reed-clogged waters of a river delta are full of potential riches,
46:35not only for birds, but for human beings.
46:37The reeds themselves are used for many purposes, but it's not an easy life here.
46:43Firm land on which to live is hard to find.
46:46In the delta of the Danube, the few solid sandbanks are tightly packed with dwellings.
46:52Earth has to be carefully conserved with piles to prevent a slight change in the current from washing it away.
46:58And there's the ever-present threat of a rise in the water level,
47:01caused not only by heavy rainstorms upstream, but an unusually high tide,
47:06backed by a storm sweeping up from the sea, which can cause devastating floods.
47:13In the twin, joined deltas of the Tigris and Euphrates in Iraq,
47:18the Marsh Arabs have become specialists in an amphibian life.
47:22Their houses seem to have solid enough foundations.
47:33In fact, they are floating on rafts of reeds.
47:37Some are the most elaborate constructions,
47:57yet all these soaring arches and roofs are also made from bundles of reeds.
48:02And reeds provide food for the livestock,
48:07so gathering them is a daily and never-ending chore.
48:10The herds have to be as much at home in the water
48:27as they are on their floating platforms.
48:30The rewards of this precarious existence are, of course, the abundant fish,
48:44which live all around the houses and even underneath them.
48:47So the fish and the marsh Arabs and the pelicans all flourish in one integrated community.
48:57The river has finally delivered the minerals it eroded from the mountains
49:02and the nutrients it collected from the forests.
49:04They sustain plants, which are the food for small animals,
49:08which are eaten by bigger fish,
49:10and which are ultimately gathered by great flocks of birds
49:13that, from the tropics to the Arctic, are the glories of the deltas.
49:24A blizzard of snow geese in northern Canada.
49:27Across the world in the tropics, on a delta in Papua New Guinea, magpie geese.
49:47In Australia, brolga cranes.
49:57Scarlat ibis in Venezuela.
50:03Plovers on almost any delta in the world.
50:07And equally widespread stilts.
50:25Flamingos in Africa.
50:27Flamingos in Africa.
50:37And spoonbills.
50:46Of all the deltas in the world, none is greater than that of the Amazon.
50:58For hundreds of miles along its lower course,
51:02the river has been so broad
51:03that it has been impossible to see from one side to another.
51:07Now, instead of receiving more tributaries,
51:10it splits into a tangle of separate channels.
51:15And on the last firm land on its banks
51:18stands a great and thriving port.
51:21For the river is so wide and deep
51:23that cargo ships from overseas
51:25can use it as a highway that can take them
51:28for 1,000 miles into the heart of South America.
51:33The Amazon's vital statistics are astounding.
51:37At any one time, two-thirds of all the river water in the world
51:41is flowing between its banks.
51:43Here at its mouth, at Belem, it's 200 miles across,
51:48a maze of channels and islands,
51:50one of which is alone bigger than the whole of Switzerland.
51:53And the river maintains its identity until far out into the sea.
51:58It was because of this that it was discovered.
52:00In 1499, a Spanish sea captain,
52:03sailing well beyond the sight of land,
52:06suddenly became aware that the water he was crossing
52:08was fresh and not salty.
52:11And he turned west and discovered this immense river.
52:15Indeed, it's not until 100 miles beyond the edge of the continent
52:19that particles of water which fell on the Andes
52:22complete their 4,000-mile-long journey
52:25and mingle with the salt water of the ocean.
52:34But farther along the coast,
52:36where the thrust of the river's flood is not so great,
52:38there is a halfway house.
52:41Here the water is neither fresh nor salt, but brackish.
52:44It's neither land nor sea,
52:47but banks of mud and sand
52:48that are half the time submerged and half the time exposed.
52:52And that intermediate, ever-changing territory
52:55is where we will be next time.
52:57and there is no place there in the land.
52:59Thank you, sir.
53:13My name is Peter McRae,
53:19I'm Peter McInerney,
53:21and I'd like to speak
53:23¶¶
53:53¶¶
Be the first to comment