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00:00This is a battleground.
00:22In many places, the sea is forcing the land to retreat,
00:26cutting back its cliffs and leaving islands and towers
00:29as markers of the territory that the land has lost.
00:33The debris is swept away and strewn on beaches
00:36farther down the coast as sand and gravel.
00:43In some places, the land is advancing.
00:46In the tropics, mangroves are moving out into the sea,
00:49gathering mud and building new territory for land-living creatures.
00:56Even in the mouths of rivers, where fresh water laden with sediment
01:00mingles with the salt water of the sea,
01:03new land is being created of a sort.
01:06I'm in an estuary in the west of England,
01:15and you might think that this mud is not the most attractive stuff in which to live.
01:20Certainly, any animals that do live in it have to face some severe problems.
01:25For one thing, part of their time they're out of water like this,
01:30part of the time they're underwater.
01:32The saltiness of the water, too, varies.
01:34Fresh water comes down from the land.
01:36The tides bring in salt water.
01:38And then there's the nature of this extraordinary sticky mud itself.
01:44It's so glutinous that little oxygen gets into it.
01:49But the rewards for enduring these unpromising conditions are high.
01:58Edible particles deposited every day on the surface of the mud
02:01are cautiously sucked up by the searching siphon of Scribicularia,
02:06a little mollusk whose main body, enclosed in a shell,
02:09is hidden within the mud for safety.
02:12A tiny crustacean, corofium, half an inch long,
02:16grazes on the bacteria, which proliferate in millions,
02:19breaking down the rotting bits of organic matter in the mud.
02:22Ragworms live in burrows and will tackle corofium, algae, bacteria,
02:28almost anything that's around.
02:39The puddles are flecked with floating mucus.
02:42It's produced by spire shells, no bigger than grains of wheat.
02:46The mucus attracts bacteria and the spire shells eat the lot.
02:52The peacock worm fans out its tentacles from the top of its tube
03:08to gather food particles before they settle.
03:22Beating threads on each filament of the fan
03:25transport the catch down to the mouth at the centre.
03:33While it feeds, it also disgorges a cement of mud and mucus
03:37and builds up the margin of its tube.
03:39The cockle lies with its shell agape, filtering the water by sucking it in through one siphon
03:54and blowing it out through another.
03:59Mussels use the same technique, collecting within their shells
04:02substantial quantities of the abundant and surprisingly nutritious drifting particles.
04:13When the tide goes out, they clamp their shells tightly together
04:16to keep in their moisture and to keep out their attackers.
04:19But some creatures know how to deal with that.
04:21Each individual oyster catcher has its favourite technique for dealing with mussels.
04:36It's usually the same as that used by its parents and has been learned from them,
04:40though a bird needs several years of practice before it becomes really expert.
04:44Some hunt in the shallow waters, looking for mussels that have not yet shut their shells.
04:53Others pick up unattached shells and carry them off away from the main flock,
04:58so they've got a little privacy,
04:59and there they skilfully place the mussel in such a position
05:02that they can cut it open along its hinge.
05:18Other individual birds regularly resort to brute force.
05:21They hammer their way in through the shell itself.
05:24As the tide retreats still further,
05:37spire shells are exposed,
05:39as many as 35,000 buried within a single square yard.
05:43All these mud feeders together constitute a rich prize,
05:47and there are abundant claimants.
05:49Sandpipers, on migration, depend on them.
06:06But at all times of the year, wading birds come to the estuaries to feed.
06:10The godwit, equipped with long legs and a long bill,
06:16can wade in water several inches deep
06:19and collect food before it can be reached by other birds.
06:23The curlew prefers to work out of water.
06:26Its long bill enables it to probe deep into the mud for a worm
06:29and serves equally well as a pair of forceps.
06:32The dunlin is a smaller bird and goes for smaller prey, ragworms and insect larvae.
06:42It feels for its food with its short bill.
06:45The ringed plover with a very short bill can only collect food from the surface,
07:00and locates it by sight.
07:15It usually works alone so that its prey won't be disturbed by other pattering feet
07:19and withdraw before being spotted.
07:22The scything action of the avocet collects creatures that live in the liquid mud.
07:37Their bills are very sensitive,
07:39and as soon as they close on something edible,
07:41the bird can juggle it up into its mouth.
07:45The other day is famous.
07:50Each längt has aHi auch has its turbines.
07:52If the sun isn't able to destroy the numbers,
07:55you see the deer rolls on the close reach.
07:57After many routes preserved in the flood,
07:59you can obraue.
08:01You can order from the right to the right.
08:05One of theines of the day desinfected atmosphere.
08:11The community has already thanked the stars.
08:14The quantities of food taken by wading birds from estuaries is enormous.
08:30Some species consume every day about a third of their own weight in food.
08:34In a year, a single oyster catcher, for example,
08:37can consume the flesh of over half a ton of cockles,
08:40and many a nestuary supports tens of thousands of wading birds.
08:45So these places are rich indeed.
08:50As the river brings down more and more particles of mud,
08:54so the flats grow bigger and higher.
08:57And on their surface, they develop a slimy skin,
09:03and that's formed by microscopic plants, algae.
09:06They start the process of consolidation.
09:10But soon, bigger plants get root, like this glasswort.
09:15And now the process really speeds up.
09:21As the high tide brings in more mud particles,
09:24they clog around the stems of the glasswort
09:26and don't swill back to the sea when the tide falls.
09:30So with each new tide, the flats grow higher and higher.
09:34Glasswort is a plant of the cold estuaries of Europe.
09:39In the tropics, the colonisers of mud are not small plants but trees, mangroves.
09:49This mud is the pulverized remains of rocks eroded from the Himalayas
09:54that has been carried down by the Ganges for 1,000 miles
09:57and dumped on the edge of the Bay of Bengal.
10:00This is the biggest intertidal forest of all, the Sundarbans,
10:044,000 square miles of it.
10:06And here roam many animals that usually live in dryland forests.
10:10AXIS deer.
10:24Woodpeckers, the Indian golden-banded.
10:27And wild boar.
10:38But mangrove forests can also harbor creatures that live nowhere else at all.
10:44The proboscis monkey eats almost nothing but mangrove leaves.
10:48It developed that specialism on the island of Borneo
10:50and has never spread overseas, trapped by its own specialized requirements.
10:57The mangroves themselves, however, are distributed widely through the tropics
11:07for they have evolved from many different plant families
11:10and today there are some 40 different species of them.
11:14The flowers of this pioneering mangrove are pollinated by the wind.
11:19The seed, however, doesn't immediately leave the parent tree.
11:23It starts to grow while it's still attached,
11:25producing a green shoot a foot long with a sharp end to it.
11:32If it falls when the tide is in,
11:34it floats horizontally in the buoyant salt water
11:37and may be carried for miles before being stranded.
11:40If the tide is out, then it stabs the mud
11:42and stays in that position when the tide returns.
11:46Quickly it puts out rootlets from the bottom
11:48and leaves from the top
11:50and within a few days it's firmly established.
11:56Just as in cold water estuaries,
11:58there's a lot of organic matter in this mud.
12:01But because it's so sticky, it isn't stirred up.
12:05So there's little oxygen in it
12:07and the process of rotting produces within the mud itself
12:11an acid, smelly, poisonous chemical, hydrogen sulphide.
12:17So these roots don't go down far into the mud.
12:22Instead, they support the trees by their sheer number.
12:27But what about the other things
12:29that normal roots do for normal trees
12:31like gathering nutrients and water and oxygen?
12:36Well, these roots deal with a nutrient problem like this.
12:47It has this cluster of very fine roots
12:51which don't go more than an inch or so
12:54below the surface of the mud.
12:56But then it's on the surface of the mud
12:58that the bulk of the nutrients are found.
13:01As for water, well, there's plenty of it here.
13:04The trouble is that it's salty.
13:06Some mangroves deal with that problem
13:08by having a special membrane
13:10around the cells in the root hairs
13:12which filters off the salt.
13:15Others actually absorb the salt
13:17but then excrete it from the leaves
13:19or concentrates it in the leaf
13:22and then the leaves are shed.
13:23And oxygen, well, there are several different solutions to that problem.
13:28This mangrove has pores actually in these prop roots
13:33which absorb the oxygen directly.
13:36And this one has roots which actually grow upwards
13:39so keeping pace with the rising surface of the accumulating mud.
13:44But it's not only plants in the mangrove swamps
13:47that have difficulty in getting oxygen
13:49but so do animals.
13:51And this time, low tide,
13:53is a period of particular difficulty.
13:57Many of the mollusks,
13:58like cockles and mussels elsewhere,
14:00simply shut their shells
14:01to keep what moisture they have
14:03and wait for the food and oxygen-bearing water to return.
14:06For them, this is a period of complete inactivity.
14:09But for other creatures, it's just the opposite.
14:25The mudskipper, of course, is a fish.
14:28There are several different kinds.
14:30This one lives near high-water mark
14:32and is the sort that spends most time out of water.
14:35It has to keep its skin moist
14:37for it absorbs oxygen through it.
14:40It also keeps its mouth full of water,
14:42swilling over its gills.
14:46It feeds on the little crabs that graze on the mud.
14:54And having got one,
14:56it needs another mouthful of water.
15:02A second kind lives close to low-water mark,
15:10so it's only out of water for an hour or so each day.
15:13It sifts the liquid mud
15:14for small crustaceans and worms.
15:27In between these two kinds
15:29lives the largest of the three.
15:30It is a vegetarian,
15:32collecting algae and other microscopic plants from the mud.
15:42And it, too, nips back every now and again for a wet.
15:50It guards its grazing rights with vigour,
15:53building walls around its territory.
15:54And when neighbours meet,
16:05there's trouble.
16:06There's trouble.
16:06On clear mud,
16:18their territories form a patchwork of walled ponds.
16:22These flats are very flat,
16:23so when a male starts to advertise for a mate,
16:26he has to be a bit of a gymnast.
16:28When a female is finally enticed into his private pond,
16:43he can continue his courtship at close quarters
16:46in a more conventionally fish fashion,
16:49with flexed fins,
16:50waggling tail
16:51and enormous excitement.
16:53RANTAMO
16:59RANT��
17:00They'll spawn in a burrow at the bottom of the pond.
17:30This crab is too big to be intimidated by mudskippers, even when it does wander through their territories.
17:49Its scissoring mouthparts not only sort out its food, but help it to breathe.
17:54On top of its shell, there's a puddle of water, and as its mouthparts move, they circulate
17:59this down into a gill chamber within the shell, out again, and up to the reservoir on the
18:03top.
18:04Eventually, the oxygen in the water is exhausted, and the crab has to return to the sea, tip
18:10it off, and get a fresh supply.
18:16Close by the edge of the sea, the tiny soldier crabs feed with frantic haste.
18:20It's not that someone else is likely to steal their mud, just that they have to eat an enormous
18:26quantity to extract the few particles necessary to keep alive.
18:30They have to work at it pretty well nonstop, and have no time to waste.
18:43High up, beyond the reach of all but the highest tides, lives the large mangrove crab.
18:49It keeps moist by boring its hole as much as six feet deep to reach permanent water.
18:54The lure that tempts it out is a newly fallen mangrove leaf.
19:03And quickly back to safety.
19:09Among the air-absorbing roots of the mangroves, fiddler crabs are busy.
19:14The females collect mud with both pincers, working with the same frantic speed as the
19:19soldier crabs.
19:23The males need to munch just as much mud as the females, but they have to work with one
19:27hand only, for one of their claws is so big that it's useless for feeding.
19:34They use it instead to wave at passing females.
19:44But it's also a weapon to brandish at rivals.
19:52A less well-equipped male gets a nasty hammering even before he can get out of his hole.
20:08The claw is long enough to reach down into the burrow to give his opponent a tweak where
20:12he's least expecting it.
20:22The purpose of the wave is to encourage a female to follow a male into his burrow.
20:31Is it possible perhaps just to take a moment or so off from munching mud?
20:48At low tide there's lots for birds to eat on the mangrove mud, just as there is on estuaries
20:53elsewhere.
20:54Terns hawk for fish that are easier to catch now in the shallowing waters.
21:00Kingfishers pounce on the fiddler crabs.
21:11Let white heron stalk and stab.
21:33The returning tide signals all change for everyone.
21:42This African mangrove snail crops the algae growing on the mud.
21:46But it mustn't stay there when the tide comes in, for it would be attacked by fish.
21:51So it takes refuge up in the trees.
21:54The speediest climb is barely faster than the rise of the tide, so it has to set off in
21:58good time and has some sort of internal alarm clock that tells it when it should do so.
22:18The soldier crabs are so well adapted to their life scavenging on the exposed mud that they've
22:23become breathers of air and without it they will drown.
22:27As the tide advances, each constructs itself a little igloo which traps a bubble of air with
22:33which the crab can breathe while the tide is in.
22:53The mudskipper's territorial walls built with such labour are breached by the incoming wavelengths.
23:03Further up, the mudskippers shelter in burrows.
23:14The incoming tide brings new creatures into the swamps.
23:18Shows of fish arrive, searching for morsels that may have been deposited by the river while
23:23the tide was out.
23:29In the swamps of South East Asia, archer fish feed on insects that have fallen on the surface.
23:41Uniquely, they also have a way of collecting insects from above the water.
23:47There's a groove in the roof of their mouth so that a subtle thrust of the tongue produces
23:53a spurt of droplets like a water pistol.
24:03When there's a crowd, a marksman can't be sure of getting his prize.
24:19So in company, it may be better to try a direct assault.
24:46The larger fish are themselves food for otters.
24:50But these hunters have broad appetites and will enthusiastically tackle snails, crabs and
24:56even mussels.
25:01They're great travellers, swimming for many miles up into fresh water or down into the sea and
25:19even out to offshore islands.
25:21And they have an enormous appetite for play.
25:36The largest of all living reptiles is found among mangroves, the estuarine crocodile, a monster
25:44that grows to 23 feet long.
25:55So one of those, it's the most lucky to have ever seen before.
26:00Will found the plant again in this sedan, for many years.
26:05I'm sorry for that.
26:06I don't think that is what is supposed to be doing.
26:08It's not supposed to be.
26:09I don't think that is what is supposed to be.
26:10No one of the questions or questions.
26:12The other questions can be answered...
26:14Like its ancestors that lived when dinosaurs dominated the earth,
26:36it's an ocean-going creature,
26:38and as a consequence, it's the most widely distributed of all crocodiles,
26:42living from the Bay of Bengal through northern Australia to the Pacific,
26:46even reaching such isolated mangrove swamps as those on the islands of Fiji.
26:53As the mangroves establish themselves farther and farther out into the sea,
26:58the mudflats they've built grow higher and higher.
27:01Rainwater washes them clean of salt,
27:03and eventually they become dry, fertile forest beyond the reach of the sea.
27:07The banks of mud and sand that the rivers lay down around their mouths,
27:15even when they're not big enough to rise above water,
27:18protect the land against the attacks of the sea,
27:20for tall waves can't travel across shallow water.
27:24But if a current sweeping down the coast carries away the sediment
27:28and scours the seafloor clean,
27:31then waves arrive at the coast full of power.
27:34The sea of mud and sand that the sea of mud and sand that the sea of mud
28:04the sea, then the territory between the tides is not miles across,
28:07but condensed into a narrow band.
28:10The creatures that live here, like all intertidal creatures,
28:13are constantly threatened by two dangers.
28:17At the high watermark, there are the physical problems of simply being dried out.
28:22And at the low watermark, there are biological problems
28:25of animals that creep up from the sea to prey upon the intertidal creatures.
28:29The interplay of those two sets of problems produces a series of horizontal bands along the coast,
28:37each dominated by the particular species which best deals with the problems at that particular level.
28:44Such bands can be seen on coasts all over the world.
28:49But here, on the northwest coast of America, they are strikingly clear.
28:54The bottom band of all is only fully exposed when the moon and the sun are in such an alignment
29:00that they pool together and the tide withdraws a long way from the edge of the dry land.
29:04The organisms here can only tolerate a brief exposure to the air,
29:09for they have no special devices to prevent themselves from being dried out.
29:18The sea urchin in water gnaws away at encrusting algae.
29:23But out of water, it can do nothing but simply hang on to the rocks.
29:30Alongside them, giant sea anemones droop their tentacles,
29:34and many withdraw them, for in air there's nothing to feed on.
29:37Sea squirts can only filter for their food spasmodically.
29:58Starfish are meat eaters, and this species feeds on mussels.
30:03It envelops them with its adhesive arms,
30:05slowly wrenches apart their shells and feeds on the flesh within.
30:09Below low-water mark, they kill any mussel that tries to establish itself.
30:14But like so many of these low-level creatures, they can't feed out of water.
30:18So a little higher up, where the rocks are regularly exposed to air for slightly longer,
30:23conditions favour the mussels, and they form a dense band,
30:27cropped at the lower edge by starfish, but beyond their reach, higher up.
30:35The massed mussels provide shelter between them for lots of other creatures.
30:41Small starfish, too small to tackle a mussel,
30:45worms and crustaceans, winkles and other mollusks.
30:49The mussels hold onto the rocks with bundles of threads,
31:00but they can't withstand the pull of the roughest of the waves,
31:03and in the winter storms, sheets of them may be ripped away.
31:06In more exposed places, where the waves beat with a particular ferocity,
31:25mussels give way to goosenecked barnacles,
31:28which clasp the rock with a long, fleshy foot.
31:31They feed by holding out stiff, fan-like arms,
31:46which catch particles from the waves,
31:48not when they crash in, but as their waters flow gently back.
31:52On the most exposed promontaries of all,
32:15the mussels are actively ousted by a plant,
32:18an odd-looking alga known as a sea palm,
32:20which lives only on these north-western coasts of North America.
32:26The crown of leaves at the top of its rubbery stem
32:29is the device which enables the sea palm to harness the power of the waves
32:33and use it to attack the mussels.
32:36The plants, perhaps surprisingly, are annual.
32:41In the spring, an individual plant may achieve the difficult feat
32:45of getting hold of an individual mussel in the mussel bed,
32:50as this one has done.
32:52When it's mature, it will produce spores,
32:56but only when it's out of water, as it is now.
33:00So, instead of the spores being distributed widely throughout the sea,
33:04as those of other plants are,
33:07the spores of the sea palm
33:09tickle down the grooves in these leaves
33:12and into the mussel bed here.
33:15When the first storms of the autumn come,
33:19they may catch underneath the fronds of this plant
33:24and rip it up,
33:26but the whole fast grips the mussels so firmly
33:29that the mussels come away with it,
33:32revealing the bare rock.
33:33And that means that the offspring of other nearby plants
33:39can get a hold on the bare rock.
33:43So, by the sacrifice of one palm growing on a mussel one year,
33:50next year there will be a whole grove of palms
33:53growing firmly on the bedrock.
33:56But mussels do require a certain amount of immersion every day
34:12if they are not to dry out and die.
34:15And this line marks exactly that.
34:19Above it, no mussel can live.
34:21But the features that can are these, barnacles.
34:25Tramped tightly to the rocks,
34:28they conserve very effectively indeed
34:30the moisture within their shells.
34:32They manage to collect the minute quantities of food
34:35they require to grow and reproduce
34:37from the relatively infrequent submersions at high tide,
34:41which in some cases may only occur
34:42for an hour or so once a month.
34:55So, each level on a rocky shore
35:12is dominated by the organisms
35:14that best deal with the precise combination
35:17of pounding by the waves,
35:19exposure to the air,
35:20and attack by deep-water predators.
35:23But none in the long run
35:24can claim permanent occupation
35:26for the attacks of the waves are unceasing.
35:28The air attack on the exilional
35:31would beoded by the man
35:39really few인을 break our boat
35:41and some striking possibilities
35:42but not only the air there are
35:43erstmalating some
35:43uniforms
35:44or theです will be
35:45those that are unceasing
35:46in the road
35:47makes its own
35:49fasteners
35:50behave
35:54like
35:54letting
35:55whatever
35:56With unfailing accuracy, the sea picks out the softer parts of the rocks and cuts its
36:02way into them. Water, at great pressure, is driven into joints and cracks until it penetrates
36:09a cliff and forms a blow-up.
36:12On the southernmost tip of Australia, storms of great ferocity, sweeping up from the south
36:21with the full force of the Antarctic gales behind them, beat away at sandstone cliffs which
36:27have lines of weakness that run horizontally and vertically.
36:32So the rock is cut away in huge blocks.
36:51The sea, having demolished the cliffs, then works on the debris. During storms, it picks
37:16up the boulders and hurls them at the cliff face. At calmer times, it rolls the rocks
37:21over the seabed and casts them up on shingle banks. Every movement chips and grinds the
37:27fragments until eventually they're reduced to sand grains. And now even a gentle current
37:32can pick them up and carry them for miles down the coast, eventually to abandon them
37:37in banks and strands, in the lee of islands or in sheltered bays.
37:44The Earth.
37:57Conservation, Maeve Admiral, is driven to incorporate waves of the sea.
38:07The valley of the kind
38:11¶¶
38:41Every wave of every tide stirs up the surface of the sand,
39:01so plants find it impossible to get any grip on it,
39:04as they can on rocky shores or mudflats.
39:08So a beach like this looks as lifeless as any part of the margins of the land.
39:16But if the sand grains are not too small and compacted,
39:20then each will retain around it a thin film of moisture,
39:24even when the tide is out,
39:26and in that microscopic space, animals can live.
39:29These translucent boulders are, in fact, sand grains,
39:37and the tiniest snake-like animal,
39:40a worm that could sit on a pinhead.
39:42All these inhabitants of the sand are necessarily adept at writhing, gliding, and crawling,
40:03as they search for the few edible fragments that are trapped between the grains,
40:08or pursue one another.
40:09This one is only a temporary lodger in the sand.
40:25It's the larva of a mollusk.
40:31A hydra lives here.
40:33It's like the one that's common in freshwater ponds,
40:35but it has one elongated tentacle with which it anchors itself.
40:41A nematode worm produces glue from a gland on its tail,
40:45which helps it to maintain its position.
40:47And this is another larva that, at the beginning of its life,
40:59floats in the sea, but settles down into the sand to continue its development.
41:04It builds a tiny tube of mucus, which it carries about with it,
41:08and clings to with bristles on its franks.
41:10When it grows up, it does the same sort of thing on a larger scale, above the sand.
41:24It's a worm called the sand mason.
41:29Now it not only builds a tube, but it adds long tassels to the top.
41:33These slow down the water so that suspended food particles fall,
41:37and can be gathered by the waving tentacles.
41:40In this shifting sand, the tubes need constant renewal,
41:43and this is how the sand mason does it.
41:46Speed it up 125 times.
42:07Although plants can't grow on these perpetually moving sands,
42:34those dislodged from the rocky parts of the coast by waves are often washed up here,
42:39and there are plenty of creatures on the beach waiting for them.
42:55These are sand hoppers.
42:57They've been hiding below the surface to avoid being baked and dried out by the sun,
43:01but now there's food to be had.
43:20On many beaches, their numbers are astronomic.
43:23There can be as many as 25,000 of them in one square yard of beach sand.
43:28The sand hoppers favour rotting vegetation.
43:45Rotting flesh attracts crabs.
43:48The remains of a squid is a banquet for ghost crabs.
44:00The remains of a squid is a banquet for ghost crabs.
44:00Occasionally, when there's a chance,
44:23it may be better to cut off a length and haul it away
44:26to consume it in the privacy of a burrow.
44:28The crabs and the shrimps live close to the high tide mark,
44:37but the incoming waters also bring with them another team of scavengers.
44:43This periscope on a South African beach belongs to a mollusk, a plough snail.
44:48It inflates its plough-like foot by pumping in water,
44:57and it uses it not so much as a ploughshare, as a surfboard.
45:02The waters pick it up and wash it swiftly inshore,
45:05together with its potential food.
45:10A stranded jellyfish.
45:12The plough snails detect its presence from the taste of decay in the surrounding water
45:26and advance on it with great speed.
45:29AVAILABLE hawkat
45:41To avoid being swept up the beach and being stranded,
46:09they eat fast and then, while there's even some food still left,
46:13they burrow into the sand.
46:15There, they wait for the tide to turn,
46:17so that they can ride back on their surfboards
46:20to deeper water and safety.
46:28Very few sea creatures can venture above the limit of the highest tide and survive.
46:34One group of animals, however, is compelled to do so
46:37by the nature of their ancestry,
46:39and on this one beach in Costa Rica,
46:41they stage an astonishing invasion.
46:46Turtles.
46:47They are ridleys, the smallest of the sea-going turtles,
46:50only a couple of feet long.
46:52Turtles are descended from land-living reptiles,
46:56and like all reptiles, they lay eggs that can only develop and hatch in air.
47:00So every year, adult females, having mated at sea,
47:04must make their way onto dry land.
47:11They arrive at a rate of up to 5,000 an hour.
47:15They use only one or two of the many thousands of beaches that seem to be suitable,
47:20and what is more, they only choose to do so on just a few nights in the year between August and November.
47:35Efficient though their flippers are in water,
47:37on land they are barely strong enough to lift the turtle clear of the sand,
47:41and it has to drag itself up the beach.
47:46This mass breeding may be an advantage to the turtle,
47:49for since it only occurs on a few nights of the year,
47:52their eggs can't support a large permanent population of predators,
47:56as they might if the turtles were to lay over several months.
47:59Yet even so, for reasons that we still don't understand,
48:03less than one in a hundred of the eggs produces a hatchling which reaches the sea.
48:10Each female lays a hundred or so.
48:13of the eggs,
48:14of the eggs.
48:15of the eggs.
48:26That done,
48:27she carefully fills in the hole.
48:43A few coatimundi and vultures come down from the forest to plunder,
48:51but they make little impact on the millions of eggs that are laid.
49:03Next night, many thousands more ridleys arrive.
49:13On other beaches, more secretly, other, very different turtles are laying.
49:23This is the largest of all the marine turtles.
49:30This magnificent creature is the giant leatherback turtle,
49:35and it's a most mysterious animal.
49:38It's a solitary wanderer of the oceans.
49:42Individuals turn up almost anywhere in the tropics,
49:46but they go much farther than that.
49:49They've been recorded as far south as Argentina
49:51and as far north as the British Isles and North America.
49:55But it's a creature of mystery because, although we know what it feeds on,
49:59which is sea urchins and fish and, oddly enough, jellyfish,
50:04we know very little else about it.
50:06We don't know how long they live.
50:09We don't know how male finds females.
50:11We don't know, indeed, how females navigate to find traditional nesting sites like this one.
50:18Indeed, we didn't actually know where the main nesting sites were until about 25 years ago.
50:24And then it was discovered that some nested on the Suriname coast of South America
50:30and some nested here on the east coast of Malaysia.
50:34Of course, the people here have always known about the turtles
50:38and they've always plundered those eggs.
50:42Today, however, there are more people than ever here,
50:46and the eggs are plundered more seriously.
50:49So, undoubtedly, this huge and extraordinary creature is in danger.
50:56But maybe the leatherback turtle has other breeding grounds that we don't yet know about.
51:02Maybe it goes to small, tiny coral islands away in the emptiness of the ocean
51:08to find beaches far away from man.
51:12And that, indeed, is where we ourselves will be going in the next programme.
51:17Thank you so much for joining us.
51:38Thank you for joining us.
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