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00:00Out of all our planet's epic waterworlds, one stands still against the forces of Tide and Time.
00:15Deep, calm and serene, these vast reservoirs of water support life above and below their glassy surface.
00:31Born from ancient glaciers and volcanic fury, these still waters offer sanctuary and a birthplace for evolving lifeforms.
00:48Every lake has its own enchanted story to tell.
01:01Take a dive into our planet's mesmerizing world of water.
01:13From the monumental open ocean to the rugged coasts that serve as the dividing line between two worlds.
01:22From the changing rivers that carve through continents.
01:28To mysterious lakes and swamps.
01:35Immerse yourself in the magic that unfolds.
01:42As we reveal the secrets of our enchanted waters.
01:58There are as many as 300 million lakes scattered across our planet.
02:07From unfathomably epic.
02:10To vital support systems.
02:13Lakes are essential to existence on Earth.
02:16They are both cradles of life.
02:19And forces of change.
02:24In Africa, one ancient lake doesn't just support a species.
02:30It once played a pivotal role in transforming it entirely.
02:34Lake Malawi.
02:35One of the oldest and deepest lakes on Earth.
02:44These waters have nurtured one of the planet's most extraordinary families.
02:49A thriving population of cichlids.
02:52A species of tropical freshwater fish.
03:02This cichlid mother is trying to keep track of her brood.
03:07Her young are so tiny that she hides them in the safest place of all.
03:11Inside her own mouth.
03:15Any passing creature would never know about her secret cargo.
03:22But the problem comes when it's time to eat.
03:28So she releases her fry amongst the rocks to feed on the algae.
03:35Whilst remaining vigilant.
03:37All present and correct.
04:00Surprisingly, the attack came from a fellow cichlid.
04:03One that looked different to her.
04:07And a flesh eater.
04:10A reminder that in Lake Malawi, not all cichlids are the same.
04:16Over 700 cichlid species share these waters.
04:26They all originated in this one lake from a single ancestor.
04:31So how did they become so different?
04:35Over millions of years, the lake has undergone dramatic changes.
04:40Long ago, shifts in the climate shrank the lake.
04:46Isolating the cichlids into separate, smaller pools.
04:49In these individual environments, one species diverged into many.
04:58Some became hunters.
05:01Others, grazers.
05:03Others, grazers.
05:06And then there were the sand sifters.
05:09When the waters finally returned, and these fish reunited, it revealed a dazzling kaleidoscope of life.
05:19Hundreds of different cichlids species.
05:26Of all colors, shapes, and personalities.
05:31All rooted in one ancient ancestor.
05:35And shaped by the lake itself.
05:37With such a diverse extended family, it's hard to know who you can trust.
05:50So when protecting your young, it pays to have a backup plan.
05:54Amongst the mother's brood are two fry with different markings.
06:01Orphaned young from another cichlid species.
06:05Extra fry means extra chances.
06:09A strategy that improves the odds of her own young surviving if a predator strikes.
06:14For four weeks, she will protect and nurture them all.
06:26Such devotion is rare in aquatic environments.
06:31But for the cichlids of Lake Malawi, it can be your own relatives you need to be wary of.
06:38This lake's remarkable history gave rise to this unique profusion of life.
06:46But the story of how it came into being is even more dramatic.
06:54The origins of our planet's lakes take many forms.
06:58Each shaped by the elemental forces of nature.
07:01Fire, ice, wind, and earth.
07:10Combined to carve out unique worlds where water comes to rest.
07:15The oldest formed as the earth's crust was torn apart by tectonic forces.
07:23As continental plates shifted, water found its way into the deep crater.
07:27Turning these open wounds into vast, sunken lakes.
07:32Like East Africa's Rift Valley.
07:35Many take advantage of more recent volcanic fury.
07:40When mighty volcanoes die, their craters fill with rainwater.
07:45Ash and sediment in the water scatter light waves.
07:49Producing vivid blue calderas.
07:52Even rivers create lakes.
07:53When their flow of water changes course, bodies of water can be cut off by land.
07:55Leaving behind a more curious-shaped outline.
07:56And in deserts?
08:13layers emerge near rivers.
08:19And sleep for hundreds of miles on the surface.
08:21It's described for Israelites, thelinear cortex are on the beginning.
08:23And in deserts, lakes are created by wind.
08:28Powerful gusts mold shifting sand dunes into deep hollows.
08:33These depressions collect rain or underground water to form aeolian lakes.
08:40Temporary oases in arid landscapes.
08:48And then there are the lakes born of ice.
08:54During the last ice age, colossal glaciers sculpted valleys deep into the land.
09:03When the ice melted, these chasms filled with water.
09:11Giving birth to freshwater giants like the greats of North America.
09:15Each lake's origin is different.
09:23But they all hold one thing in common.
09:27Where water comes to rest, life takes root and thrives.
09:34Their stable, slow-flowing waters transform these basins into vibrant epicenters of life.
09:46Nurturing countless species and supporting entire ecosystems for millions of years.
10:02Southeastern USA.
10:03In the heart of the backwaters.
10:09The sleepy lakes here are home to a prehistoric monster that has seen the world change over eons.
10:20The sleepy lakes here are home to a prehistoric monster that has seen the world change over eons.
10:34But has resolutely remained the same.
10:41The alligator snapping turtle.
10:49The alligator snapping turtle.
10:51With a lineage stretching back over 90 million years.
11:02The narrator says,
11:08She has seen it all.
11:16Weathering mass extinctions and climatic shifts without flinching.
11:26These freshwater lakes served her ancestors well, and now, this cantankerous sentinel
11:37remains steadfast.
11:40She ain't budging.
11:44Her spiked shell, like a camouflaged fortress, evolved as a defense against ancient reptiles.
11:55Her secret to survival isn't speed or strength, it's patience, and doing as little as possible.
12:13Especially when it's time to hunt.
12:17This souled dragon doesn't chase prey.
12:21Why waste energy?
12:23Instead, she waits.
12:27Motionless on the lake bed for up to 50 minutes.
12:33And lures them in with a deadly trick.
12:39A worm-like appendage on her tongue mimics a tasty morsel.
12:45For her ruse to work, she must remain still.
12:48This timeless tactic remains as effective today as it was millions of years ago.
12:58And if it ain't broke, don't fix it.
13:05But hunting isn't the only thing she puts minimal effort into.
13:08Three months ago, she buried a clutch of eggs on the lakeshore.
13:18Her choice of location provides a safe base close enough to the water.
13:28Beyond that, she offers no help.
13:29Over her 100-year lifetime, she'll lay thousands of eggs.
13:38Over her 100-year lifetime, she'll lay thousands of eggs, but provide minimal care for any of them.
13:54Yet her hands-off parenting seems to work.
14:01Her hatchlings are born ready to fend for themselves.
14:06They emerge with a yoke still attached.
14:13This will nourish the newborns for the first few days of their lives.
14:18No parental care required.
14:23After that, the lake becomes their caregiver.
14:27For countless generations, its waters have provided food and shelter for these stubborn reptiles.
14:34Who remain defiant in a world of constant evolution.
14:49Lakes, with their calm nature, are nurturing environments.
14:54But with such diversity within its waters, they need an ally to share the burden of care.
15:03The water lily.
15:07Across many of Africa's lakes, constellations bloom.
15:16These delicate flowers are the lake's quiet assistance.
15:23Working alongside it to nurture life on every level.
15:29Nourished by the lake's nutrient-rich sediment, their broad pads form floating islands across
15:39the surface.
15:43Creating a natural sunshade to keep the lake water cool.
15:49And providing refuge for hatching larvae.
15:54Juvenile fish.
15:57And tiny amphibians.
16:03The lilies also help keep the lake healthy by absorbing excess nutrients and filtering
16:13out pollutants through their roots.
16:16Maintaining the lake's purity for all who rely on it.
16:21Above the surface, the lilies' blooms support entire networks of pollinators.
16:31Which in turn attracts the bug eaters.
16:37Like jacanas, for whom the lily pads act as a walkway.
16:46Their wide feet are perfectly adapted for gently stepping across the floating leaves to find
16:51food.
16:53They even use the lily pads to lay their eggs.
16:59And raise their chicks.
17:03But for water lilies to extend their care to other lakes, they need a little help.
17:10From giant visitors.
17:15Elephants feast on their nutritious roots and seeds.
17:20This disruption, far from harmful, creates new opportunities for life to thrive.
17:29These hungry beasts are a reliable method of transport.
17:33Helping to spread the lily's seeds far and wide across the region's lakes.
17:40Allowing the plants to offer their care to many others in need.
17:47Working with the lake as caretakers.
17:53Protectors.
17:55And providers.
17:57Water lilies are a life support system for all of the lake residents.
18:04And as the lily pads rest upon the lake's surface, they reveal the delicate balance wielded by
18:10an unseen force of nature.
18:17The still surface of a lake holds a hidden power.
18:23A mysterious force that turns water into a shield.
18:30Surface tension.
18:33When molecules interact at the water's surface, it creates an invisible elastic membrane.
18:40Long enough to hold up steel, granting superhero-like powers to the creatures that have learnt to exploit it.
18:50Pond snails defy gravity to travel on the underside of the surface.
18:57By secreting a thin layer of mucus between its foot and the top of the water, it can crawl along, upside down, to graze on the algae-rich biofilm floating there.
19:13Some mosquitoes use this force field to turn water into a life-saving raft.
19:24The female lays her eggs directly on the water.
19:31The eggs themselves are not buoyant, but are saved from drowning by the power of the lake's surface tension.
19:40Even when fused into clusters of up to 400 eggs, the lake can still support them.
19:49When the eggs hatch, the emerging larvae escape into the water.
19:55But these insects are air breathers.
20:01So they hang upside down from a snorkel-like breathing tube.
20:06Both piercing the surface tension to break through it, and using its strength to keep them afloat.
20:21And then there's one creature who uses surface tension to literally walk on water.
20:31This skin-like structure enables pond skaters to conquer the water one step at a time.
20:51It uses its long, slender legs to distribute its weight evenly.
21:00And its body, covered in hydrophobic hairs, repels water and traps air, allowing it to glide smoothly like an ice skater.
21:15Turning the hidden forces of surface tension into a superpower.
21:22While only the most finely tuned species can work their magic on the lake, within its depths lies an extraordinary shapeshifter, waiting for the transformation of a lifetime.
21:43This dragonfly nymph has spent the last two years living at the bottom of a lake.
21:52But a life spent underwater is not his ultimate destiny.
21:59To reach his full potential, he needs patience and the essential support of these waters.
22:12As a tiny nymph, down here he's both predator...
22:21...and prey.
22:25With a voracious appetite, he devours his fellow larvae in this well-stocked lake.
22:33As he grows, he molts, casting off his exoskeleton, leaving a remnant of his old, smaller self behind.
22:45Having conquered this underwater world, it's time for a new adventure.
22:51A life in the skies!
22:56Barely out of the water, he takes his first breath of air, through the spiracles running along his abdomen.
23:04His gills are now useless, so he must hold on tight.
23:08If a gust of wind dislodged him, he would fall and drown in his lake.
23:14The moment has come for his final molt.
23:23This time, his gossamer wings are carefully unveiled.
23:29He redistributes every drop of water in his entire body to finally become...
23:35...a creature transformed!
23:39But after spending 95% of his life underwater...
23:46...he now has just one week to fulfill his life's purpose.
23:54He might look very different, but the lake can still provide everything he needs.
24:04His compound eyes have increased in size, to allow him to see his new surroundings in ultra-high definition.
24:16Despite being his first time out of water, he is an intuitive flyer.
24:23And hunting here requires the same killer instinct...
24:27...and lightning-fast reactions.
24:31But his ultimate goal is to find a mate...
24:41...along with every other male dragonfly around this lake.
24:46Battles for survival underwater turn into aerial battles above the surface...
25:00...as each male fights to prove his worth.
25:04By successfully out-competing his rivals, he has secured the best strip of lakeside water...
25:18...perfect for egg-laying.
25:23...and an impressed female soon follows.
25:38She has been swayed by his choice of territory.
25:42Together, they form a mating wheel...
25:52...as he fertilizes her eggs.
25:56...and the female releases them into the depths...
26:11...entrusting the lake with their care.
26:14With destinies now fulfilled, the pair's lives will shortly come to an end.
26:25Although a dragonfly's life as an aerial acrobat is short but dazzling...
26:30...they, like many creatures, are born of water.
26:35And the ability to struddle both worlds can prove seductive.
26:49In the remote mountain forests of southeastern Europe...
26:54...a reluctant recluse is about to make a big splash in a secret woodland lake.
27:00Something is stirring on the forest floor.
27:12This male alpine newt, having lived for three years as a juvenile in the woods...
27:18...is finally mature enough to seek out a mate.
27:23Drawn by an almost magnetic pull, he heads for the secluded pool...
27:35...where he was born...
27:37...to secure...
27:38...his own legacy.
27:40It's the biggest event of the year.
27:44All of the newts in the region will be there.
27:48Shy by nature...
27:55...now the time has come...
27:57...to take the plunge.
27:59He began his life underwater...
28:04...and can still breathe through his skin.
28:09But other remarkable transformations are underway.
28:14His once muted tones are enhanced in the water...
28:18...revealing a blaze of tropical colors...
28:21...now visible in their full glory.
28:24He might look the part...
28:30...but this is his first rodeo.
28:33So he follows the crowd.
28:36The competition is fierce...
28:41...with larger, more mature suitors vying for the female's attention.
28:46Struggling to stand out...
28:52...he is rejected.
28:56He's going to need a little help...
28:59...and it's the lake that has the power to turn his fortunes around.
29:05He carries with him a love potion...
29:08...activated only in the water.
29:11Spotting a lone female...
29:15...he cautiously approaches.
29:18And she immediately swims off.
29:33But it's merely for a gulp of extra oxygen.
29:44Could that be a good sign?
29:48Perhaps she's preparing for a long courtship.
29:54Buoyed with hormones...
29:55...now is the time to deploy his secret weapon.
30:02He releases a cloud of pheromones into the water...
30:05...and gently fans them with his tail.
30:10Mixed with the lake's waters...
30:12...they become a seductive force.
30:15The love potion works.
30:27He releases his seed into the water...
30:33...and she accepts it...
30:39...sealing their union.
30:44She'll lay up to 400 eggs...
30:50...his legacy secured in the same lake where he was born.
30:54A flashy outfit...
31:02...an intoxicating elixir...
31:04...and the lake's magic...
31:05...were all he needed for a successful evening.
31:09Now it's time to return to the undergrowth...
31:14...and await next year's chance...
31:16...to try again.
31:18To be continued...
31:25Fed by rain, rivers and snowmelt...
31:28...freshwater lakes are generally nurturing...
31:32...calm and dependable...
31:34...while others can be more treacherous...
31:38...and sinister.
31:39When a lake becomes overburdened...
31:43...with too much organic matter...
31:45...its water turns acidic.
31:48Its pH value drops dangerously low...
31:51...and these poisoned pools...
31:54...become too toxic for most animals to live in.
31:59These lakes in Australia...
32:01...have acidic levels...
32:02...similar to what's found in the stomachs of humans...
32:05...making them some of the harshest aquatic environments...
32:08...on Earth.
32:12But even beauty can be deceptive.
32:17Some, like Lake Tahoe...
32:19...have a dazzling mirror-like appearance.
32:24The lack of nutrients in these oligotrophic waters...
32:27...may make them crystal clear...
32:29...but it also turns them...
32:31...into ghost lakes.
32:33Unable to support aquatic life in any density.
32:42The opposite of these are eutrophic lakes.
32:47These overfed giants are so full of life...
32:51...they risk overwhelming their own waters.
32:55An influx of nutrients...
32:57...often from agricultural runoff...
33:00...acts like a fertilizer...
33:02...fueling a rapid growth spurt of algae.
33:04This clouds the water...
33:08...and blocks out any light...
33:10...eventually leading to the demise...
33:12...of other plants and animals.
33:15In worst cases...
33:17...the lake can become a dead zone...
33:20...and end up devoid of all life.
33:23Climate can also play a role...
33:26...in a lake's personality, too.
33:29If a lake becomes too shallow...
33:32...in an arid climate...
33:34...a strange thing can happen.
33:37The water evaporates under the intense heat...
33:41...concentrating the remaining salts and minerals.
33:45Over time...
33:48...if a lake is unable to refresh itself...
33:51...the water turns alkaline.
33:56The soda and salt content of the water here...
33:58...is so high...
34:00...that it would burn the skin off most animals.
34:05Only the truly extraordinary...
34:08...would choose to make a saline lake their home.
34:10Flamingos.
34:15They arrive here in their millions.
34:20Their specialized leathery scale skin...
34:22...protects them from these corrosive waters.
34:28But it would prove deadly...
34:29...to their terrestrial predators...
34:31...so the birds have exclusive...
34:33...feeding and breeding rights...
34:36...to this lake.
34:40It is this young male's first trip to the lake...
34:47...as a fully-fledged adult.
34:50He's what's known as a greater flamingo...
34:53...and his feathers have only recently begun...
34:55...to turn pink.
34:57But...
34:58...is he pink enough?
35:01As a chick...
35:02...he was born a drab gray.
35:04But he doesn't inherit his pinkness...
35:09...from his parents.
35:13Flamingos get their signature color...
35:15...from the food they eat.
35:18Feasting on one of the few other creatures...
35:20...that can survive in this caustic lake.
35:23His dancer's legs stir up the sediment...
35:29...to flush out these tiny crustaceans.
35:33They contain large quantities of carotenoids...
35:38...a pigment found in food...
35:41...much like carrots.
35:42As the flamingos sift food with their beaks...
35:47...their livers absorb these pigments...
35:49...and deposit them...
35:51...in their skin...
35:52...feathers...
35:53...and even eyes.
35:55And for adults looking to find a mate...
36:01...the deeper their shade of pink...
36:03...the better.
36:05As a sign of both good health...
36:07...and expert foraging...
36:09...it makes it easy to spot a desirable prospect.
36:16But as breeding season approaches...
36:18...our young male...
36:20...is looking decidedly pale.
36:22He is more of a...
36:25...white pink.
36:38And now...
36:39...the arrival of a flock of lesser flamingos to this lake...
36:42...is making him feel even less...
36:44...vibrant.
36:45They may be smaller than him...
36:52...but they are way pinker.
36:56This is because they mainly feed...
36:58...on the spirulina algae in the lake water...
37:00...which contains more concentrated carotenes...
37:05...resulting in a colour...
37:07...he can only aspire to.
37:09But he doesn't have the right shaped beak...
37:14...to suck up the algae.
37:16Even if he did...
37:18...his efforts will not work in time.
37:22On the lake...
37:24...groups are starting to...
37:26...synchronise.
37:28Courtship rituals are imminent.
37:31If he is deemed...
37:33...not to be the right shade of pink...
37:35...he won't be allowed...
37:37...to join in with the display.
37:39He tries to muscle his way in...
37:41...but is firmly rebuked.
37:44This year...
37:45...he has no choice...
37:46...but to watch the performance...
37:48...from the sidelines.
37:52These types of gatherings are called...
37:54...a flamboyance.
37:56Flamingos have 136 combinations...
38:03...of dance moves.
38:08This one is known...
38:10...as a march.
38:26The pale male looks on.
38:34If he keeps feeding at this lake...
38:36...he'll eventually be pink enough...
38:38...to join the dance...
38:39...and find himself a mate.
38:41Lakes can encompass...
38:54...many different environments...
38:56...and for each stage they create...
38:58...there's a unique set of performers...
39:00...that make it their own.
39:06Every part of a lake...
39:07...can provide a banquet of riches...
39:11...if you come prepared...
39:12...with the right technique...
39:13...and the right utensils.
39:20The murky shallows...
39:21...hide a myriad of secrets.
39:23So it takes a dedicated treasure hunter...
39:25...to scour these waters.
39:30Spoonbills use their sensitive beaks...
39:32...like motion-seeking detectors...
39:34...picking up the faintest...
39:36...of underwater movements...
39:37...before snapping it up.
39:47In the shallowest waters...
39:49...where nervous fish...
39:50...look for refuge...
39:51...the black heron...
39:53...takes on the role...
39:54...of a cunning illusionist.
39:58By unfolding its wings...
39:59...like an umbrella...
40:00...it conjures up...
40:01...a patch of darkness.
40:03This mirage of safety...
40:05...lures unsuspecting prey...
40:08...straight into his trap.
40:17And then there are...
40:18...the stunt teams.
40:21Even when the water is crystal clear...
40:23...it takes the keen eyesight...
40:25...and intelligence of a kingfisher...
40:27...to assess the water's refractive veil...
40:30...and lock onto its target below.
40:35With a bob of its head...
40:36...it calculates depth and position...
40:40...to ensure a clean strike every time.
40:47The lake's deepest water...
40:49...takes real power to access.
40:58Only the biggest raptors...
41:00...such as the African fishing eagle...
41:01...can dominate this realm.
41:03Its large, powerful wings...
41:05...allow it to fly low...
41:07...over the water...
41:08...and descend...
41:09...feet first.
41:14Securing his catch...
41:15...with a grip's strength...
41:16...five times...
41:17...that of a human.
41:18While these experienced hunters...
41:22...have mastered the lake's offerings...
41:24...every new generation...
41:25...must learn its lessons...
41:26...and face its hidden dangers.
41:31In waters rich with wisdom...
41:32...a tenacious youngster...
41:33...must learn all she can...
41:34...from her legs...
41:35...in waters rich with wisdom...
41:36...a tenacious youngster...
41:37...must learn all she can...
41:38...from her legs.
41:39...before it's too late.
41:42In waters rich with wisdom...
41:44...a tenacious youngster...
41:45...must learn all she can...
41:47...from her lake...
41:48...before it's too late.
41:57In the early summer stillness...
41:58...of North America's...
41:59...subarctic waterways...
42:02...an eerie sound...
42:04...slices through the morning air.
42:09The melodic call...
42:13...of a common loon...
42:15...searching for his mate.
42:26They return to this same spot...
42:28...to breed...
42:29...every summer.
42:33Loons show exceptional loyalty...
42:35...to their chosen lakes.
42:37They're more committed...
42:41...to their lake...
42:42...than they are...
42:43...to their breeding partners.
42:48A pair might stick together...
42:49...for up to five years...
42:51...but a good lake...
42:53...is a companion for life.
42:55And this couple have found...
43:01...an exceptionally good one...
43:03...to raise their chicks.
43:05This lake is a pristine...
43:17...sanctuary.
43:18It's large expanse of water...
43:20...is teeming with life.
43:21A plentiful supply of fish...
43:22...to feed their hungry youngsters...
43:23...over the next three months.
43:54Even in these early days...
43:57...the female chick's curiosity...
43:59...sets her apart.
44:01While her brother sticks close...
44:04...to their parents for safety...
44:06...she dares to explore.
44:10The lake encourages her first lesson...
44:15...look beneath the surface.
44:17Below lies a world of discovery.
44:22Loons are natural-born divers.
44:25Their red eyes enhance...
44:28...underwater vision.
44:29And their solid bones...
44:31...reduce buoyancy...
44:33...allowing dives...
44:34...of up to 75 meters deep.
44:37Thanks to the lake's generosity...
44:40...an adult loon...
44:42...can catch almost a kilo of fish...
44:45...in a single day.
44:52She's got a big legacy to live up to.
44:55And she'll get there...
44:57...eventually.
45:02The lake is patient.
45:04It has nothing but time.
45:07It has been a training ground...
45:09...for hundreds of generations...
45:11...of loon chicks.
45:16But there is another, more...
45:18...challenging lesson yet to come.
45:21The lake is not an entirely safe space...
45:24...for the little ones.
45:28Their quiet tranquillity...
45:30...is interrupted.
45:37A bald eagle.
45:51Unlikely to snatch an adult...
45:56...but a chick would be easy pickings for them.
46:00The family are too far from the edge to take cover.
46:08But they have another neat solution.
46:13A bald eagle.
46:35Her parents' protection won't last forever.
46:40Soon, the lake will deliver its final lesson, independence.
46:48When the summer's over, their parents will migrate south to the Gulf of Mexico, leaving
46:53their 12-week-old chicks behind.
46:58The rest of their education will be left to the lake, now their only teacher.
47:05This is why the parents' choice of lake is so important.
47:11A month from now, the fully independent chicks will follow their parents on their own journey,
47:17having learned everything this lake can teach them.
47:22By next spring, they'll return, not as students, but as masters.
47:33Across the globe, and in their varying forms, lakes are not just bodies of water.
47:42They are sanctuaries offering a deep well of stability in a world of uncertainty.
47:51These serene waters cradle and sustain life, providing balance and support to the world
47:58around them.
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