0:00:02 > 0:00:05Our planet is the greatest living puzzle in the universe.
0:00:05 > 0:00:09A collection of worlds within worlds.
0:00:09 > 0:00:12Each one, a self-contained ecosystem
0:00:12 > 0:00:13bursting with life.
0:00:17 > 0:00:19But how do they work?
0:00:21 > 0:00:24The intricate web of relationships
0:00:24 > 0:00:27and the influence of natural forces
0:00:27 > 0:00:32makes each microworld complex and unique.
0:00:33 > 0:00:34So, to discover their secrets,
0:00:34 > 0:00:37we need to explore them one by one.
0:00:40 > 0:00:43Untangle their interlocking pieces
0:00:43 > 0:00:47and, ultimately, reveal the vital piece,
0:00:47 > 0:00:49the key to life itself,
0:00:49 > 0:00:51hidden deep within
0:00:51 > 0:00:53each of nature's microworlds.
0:01:02 > 0:01:06Running down Africa's south-west flank lies the Namib Desert.
0:01:08 > 0:01:102,000 kilometres long
0:01:10 > 0:01:12and 200 kilometres wide,
0:01:12 > 0:01:14this is not Africa's largest desert,
0:01:14 > 0:01:17but it is its oldest.
0:01:20 > 0:01:23Created by an 80-million-year feud
0:01:23 > 0:01:24between the African coastline
0:01:24 > 0:01:27and the full force of the Atlantic Ocean,
0:01:27 > 0:01:29it's a startling place.
0:01:31 > 0:01:36The rugged coast and its sea of dunes is the stuff of legend.
0:01:40 > 0:01:43The wrecks of ships swamped by sand
0:01:43 > 0:01:46show how treacherous this place is,
0:01:46 > 0:01:49blinded by the regular sea fogs,
0:01:49 > 0:01:52dashed on the rocks by the pounding ocean.
0:01:53 > 0:01:56Even though it's been shaped by brutal forces,
0:01:56 > 0:02:00the Namib is one of the greatest natural wonders on Earth -
0:02:00 > 0:02:03but it's not for the faint-hearted.
0:02:03 > 0:02:06And that's because the Namib seems to be missing
0:02:06 > 0:02:10one of the fundamental building blocks of life -
0:02:10 > 0:02:11water.
0:02:11 > 0:02:14Some years, it doesn't rain at all.
0:02:16 > 0:02:19So it would take some truly hardy creatures
0:02:19 > 0:02:23to be able to survive in this barren, waterless place.
0:02:23 > 0:02:26In fact, the only thing more extraordinary than the landscape
0:02:26 > 0:02:29are the surprising creatures that call it home.
0:02:30 > 0:02:34Sea lions sprawling in desert sands.
0:02:34 > 0:02:39A chameleon, normally a tree dweller, but with no tree in sight.
0:02:39 > 0:02:41And a blind mole
0:02:41 > 0:02:43with no soil in which to dig.
0:02:44 > 0:02:47In fact, the Namib is home
0:02:47 > 0:02:49to over 180 species
0:02:49 > 0:02:51found nowhere else on Earth.
0:02:52 > 0:02:55To understand how this ecosystem works,
0:02:55 > 0:02:57we're going to first have to understand
0:02:57 > 0:02:59how life succeeds here at all.
0:03:01 > 0:03:03We must take a closer look at these creatures,
0:03:03 > 0:03:06explore their unique adaptations,
0:03:06 > 0:03:09understand their interactions,
0:03:09 > 0:03:11so that we can discover the secret
0:03:11 > 0:03:13that allows life to tough it out
0:03:13 > 0:03:16in the most inhospitable desert on Earth.
0:03:20 > 0:03:23Let's start at the edge of the desert - the coast.
0:03:25 > 0:03:28The freezing Antarctic waters are the key to the success
0:03:28 > 0:03:30of one particular coastal species.
0:03:33 > 0:03:36Where hot desert sands meet these icy waters,
0:03:36 > 0:03:39the South African fur seal reigns,
0:03:39 > 0:03:40in giant colonies
0:03:40 > 0:03:42several thousand strong.
0:03:49 > 0:03:53The cold currents flowing northward from Antarctica
0:03:53 > 0:03:55bring with them deep, rich waters,
0:03:55 > 0:03:57which, in contrast to the desert,
0:03:57 > 0:03:59are teeming with life.
0:04:03 > 0:04:05Seawater is far too salty to drink,
0:04:05 > 0:04:08so fish provide the fur seals
0:04:08 > 0:04:09with both food and water.
0:04:11 > 0:04:13This saves them from the dryness of the desert.
0:04:13 > 0:04:17But they are not immune to something else this desert has a lot of...
0:04:19 > 0:04:20..heat.
0:04:21 > 0:04:24They may be perfectly adapted for hunting in the breakers,
0:04:24 > 0:04:27but they can't spend all their life at sea.
0:04:27 > 0:04:31They have to come to shore to rest and to breed.
0:04:33 > 0:04:36Out of the water, the seals are vulnerable.
0:04:37 > 0:04:40The blubber that keeps them warm in the cold water
0:04:40 > 0:04:43is now more of a hindrance than a help.
0:04:43 > 0:04:44SEAL GROANS
0:04:46 > 0:04:50But the seals have developed a behaviour to combat overheating.
0:04:50 > 0:04:52Flipper sailing.
0:04:53 > 0:04:56Their flippers are the only part of their bodies
0:04:56 > 0:04:58not covered by blubber and fur
0:04:58 > 0:05:01and so, by exposing them to the breeze, they can lose heat.
0:05:03 > 0:05:06And, of course, if it gets too hot to bear,
0:05:06 > 0:05:07like holiday makers,
0:05:07 > 0:05:10the adults make a dash for the cold water to cool off.
0:05:12 > 0:05:14But they have to come ashore to give birth
0:05:14 > 0:05:17and their pups are too young to swim.
0:05:19 > 0:05:23The effects of extreme heat can be lethal.
0:05:23 > 0:05:26One in four fur seal pups
0:05:26 > 0:05:28just won't make it.
0:05:30 > 0:05:32But then, why with such a high death rate,
0:05:32 > 0:05:34are the seals here in the first place?
0:05:37 > 0:05:40The lethal heat and wind that helped create the dunes
0:05:40 > 0:05:42act as an impassable barrier,
0:05:42 > 0:05:45protecting them from the rest of Africa,
0:05:45 > 0:05:47with all its deadly predators.
0:05:49 > 0:05:52So the desert acts like a defensive wall,
0:05:52 > 0:05:55and the loss of a few pups is a small price to pay
0:05:55 > 0:05:57for the success of the whole colony.
0:06:00 > 0:06:03But they're not completely isolated.
0:06:05 > 0:06:07Black-backed jackals are one of the few animals
0:06:07 > 0:06:09that have managed to reach the coast.
0:06:09 > 0:06:14And now, they are heavily dependent on the seal colonies for survival.
0:06:17 > 0:06:20A mutually beneficial relationship's developed
0:06:20 > 0:06:22between these beach dwellers.
0:06:24 > 0:06:27The dogs are not capable of taking healthy pups,
0:06:27 > 0:06:29but, by scavenging on the dead and dying,
0:06:29 > 0:06:33they clean up the colony, preventing the spread of disease.
0:06:35 > 0:06:39It's a practical, if not a little morbid, arrangement.
0:06:41 > 0:06:43But with the beach littered with pups,
0:06:43 > 0:06:46the difference between the sick and the sleeping
0:06:46 > 0:06:48is sometimes hard to spot.
0:06:48 > 0:06:50PUP SQUEALS
0:06:51 > 0:06:53Jackals are adapted to desert life,
0:06:53 > 0:06:57having kidneys designed to handle water deprivation.
0:06:58 > 0:07:00But, without the seal feast on the beach,
0:07:00 > 0:07:02even they would struggle to survive out here.
0:07:05 > 0:07:08The seals rely entirely on the ocean,
0:07:08 > 0:07:10not just for food and water,
0:07:10 > 0:07:13but as a means to escape the desert heat.
0:07:15 > 0:07:18So understanding how they cope does not reveal
0:07:18 > 0:07:20how the rest of life can survive here
0:07:20 > 0:07:22with little to no water.
0:07:24 > 0:07:26But the coast does hold the key
0:07:26 > 0:07:29to how this desert was formed in the first place.
0:07:32 > 0:07:35The sand grains that are continually deposited
0:07:35 > 0:07:37on to the Namib's beaches by Atlantic waves
0:07:37 > 0:07:40are blown into the interior by relentless winds...
0:07:45 > 0:07:48creating a desert with some of the largest dunes in the world.
0:07:51 > 0:07:54The grains of sand that shape these giants
0:07:54 > 0:07:58may have journeyed here over 5,000 years ago.
0:08:02 > 0:08:04These dunes are actually dynamic.
0:08:06 > 0:08:09Like waves in very slow motion,
0:08:09 > 0:08:12the winds are constantly shifting and changing them.
0:08:15 > 0:08:19Bone-dry sand forms arcing crescents -
0:08:19 > 0:08:23a back slope piled up against the prevailing wind
0:08:23 > 0:08:27and a shorter, steeper slip face.
0:08:30 > 0:08:33As more sand builds up on the back slope,
0:08:33 > 0:08:36the angle of the slip face becomes critical.
0:08:36 > 0:08:39It's only a matter of time before gravity takes hold
0:08:39 > 0:08:42and the slip face crashes down.
0:08:45 > 0:08:50In this way, each dune moves along slowly but surely.
0:08:57 > 0:09:01The shifting sands are searingly hot.
0:09:01 > 0:09:04Midday temperatures regularly exceed 60 degrees.
0:09:06 > 0:09:10If a seafarer was lucky enough to escape the wrecking coast,
0:09:10 > 0:09:12they wouldn't last long out here.
0:09:15 > 0:09:18But there are animals and plants that survive here,
0:09:18 > 0:09:19where humans have failed.
0:09:20 > 0:09:23A few tough species have managed to find a foothold
0:09:23 > 0:09:26in this constantly shifting environment.
0:09:29 > 0:09:33They may be small, but they are the true giants of survival.
0:09:33 > 0:09:36All properly built to handle the heat.
0:09:44 > 0:09:47The shovel-snouted lizard's dance
0:09:47 > 0:09:49may look bizarre,
0:09:49 > 0:09:51but it has a purpose.
0:09:52 > 0:09:55It looks like it's simply getting some respite
0:09:55 > 0:09:56from the burning sand,
0:09:56 > 0:09:58but there's more to it than that.
0:09:58 > 0:09:59It's cleverly taking advantage
0:09:59 > 0:10:01of the heat dynamics
0:10:01 > 0:10:02of the dune surface.
0:10:06 > 0:10:09The air temperature is a whole ten degrees cooler
0:10:09 > 0:10:11just millimetres above the sand,
0:10:11 > 0:10:13so a raised foot can cool down
0:10:13 > 0:10:15just enough to bring relief.
0:10:20 > 0:10:24This desert lizard is so highly adapted to this environment,
0:10:24 > 0:10:27its behaviour so specific to the Namib,
0:10:27 > 0:10:30that it's found nowhere else on Earth.
0:10:35 > 0:10:39It's one of 23 species of reptile endemic to the Namib,
0:10:39 > 0:10:41each with their own unique way
0:10:41 > 0:10:43to combat the blistering heat.
0:10:49 > 0:10:52We know chameleons as tree dwellers,
0:10:52 > 0:10:56but, clearly, the Namaqua is not your average chameleon.
0:10:57 > 0:10:59To survive here,
0:10:59 > 0:11:02it too has developed an extraordinary heat-avoidance tactic.
0:11:04 > 0:11:05Like all chameleons,
0:11:05 > 0:11:07it can change its skin colour.
0:11:09 > 0:11:11However, its colour changes
0:11:11 > 0:11:14are not just about communication or camouflage.
0:11:14 > 0:11:16Here, the Namaqua uses colour
0:11:16 > 0:11:19to regulate its body temperature.
0:11:19 > 0:11:22Following a cool desert night,
0:11:22 > 0:11:23the cold-blooded chameleon
0:11:23 > 0:11:25flattens its dull, grey body,
0:11:25 > 0:11:28angling itself towards the rising sun,
0:11:28 > 0:11:30absorbing the warmth of the early rays.
0:11:35 > 0:11:38But, as the sun grows higher and hotter,
0:11:38 > 0:11:40and with nowhere to hide,
0:11:40 > 0:11:43the Namaqua undergoes a colour transformation.
0:11:53 > 0:11:56By turning a brilliant white,
0:11:56 > 0:11:58it now no longer absorbs the sun
0:11:58 > 0:11:59but can reflect it.
0:12:01 > 0:12:04An efficient thermostat.
0:12:07 > 0:12:10This astounding animal has taken an ability to change colour
0:12:10 > 0:12:13and adapted it to regulate its temperature.
0:12:13 > 0:12:17A neat example of evolution at work.
0:12:18 > 0:12:22But this is not the only way in which the Namaqua differs
0:12:22 > 0:12:24from its forest-dwelling relatives.
0:12:24 > 0:12:29Rather than the fused feet used by tree climbers to grip branches,
0:12:29 > 0:12:33this lizard is able to splay its toes wide.
0:12:33 > 0:12:37Not only does this prevent the indignity of sinking into the sand,
0:12:37 > 0:12:39but it also affords this chameleon
0:12:39 > 0:12:41something that its relatives lack -
0:12:41 > 0:12:43speed.
0:12:45 > 0:12:47And when the ground below you is searingly hot,
0:12:47 > 0:12:51it doesn't do any good to hang around.
0:13:01 > 0:13:04So, even in a world without shade or cover,
0:13:04 > 0:13:07with supremely clever temperature controls,
0:13:07 > 0:13:09or thermo-regulation as it's known,
0:13:09 > 0:13:11life has learnt to survive.
0:13:15 > 0:13:17But there is shade,
0:13:17 > 0:13:19if you know where to look.
0:13:21 > 0:13:25And so far, we've only scratched the surface of ingenuity here.
0:13:27 > 0:13:31The desert ecosystem doesn't just exist on the surface.
0:13:31 > 0:13:34There's more to discover by looking in the dune itself.
0:13:38 > 0:13:41Sand is not nearly as densely packed as hard earth.
0:13:42 > 0:13:46Between the grains, there's enough air to breathe.
0:13:46 > 0:13:49And, as we can see on this thermal image,
0:13:49 > 0:13:50the sand can be
0:13:50 > 0:13:51up to 20 degrees cooler
0:13:51 > 0:13:53just centimetres below the surface.
0:13:55 > 0:13:57So it's the perfect bolt hole to keep cool.
0:13:59 > 0:14:01Or to lay a trap.
0:14:04 > 0:14:06The Namibian spoor spider is tough -
0:14:06 > 0:14:08it can withstand higher temperatures
0:14:08 > 0:14:11than any other spider in the world.
0:14:12 > 0:14:14And its ability to tolerate the heat
0:14:14 > 0:14:16is the key to how it gets food
0:14:16 > 0:14:18in this lonely place.
0:14:18 > 0:14:22It sets its trap near an isolated grass tuft,
0:14:22 > 0:14:24then weaves sand grains together
0:14:24 > 0:14:25to create a sunshade
0:14:25 > 0:14:28that doubles as a trapdoor.
0:14:31 > 0:14:33While the spider tunnels below,
0:14:33 > 0:14:35it provides perfect camouflage.
0:14:36 > 0:14:38Only a single strand of silk
0:14:38 > 0:14:40reveals a more sinister agenda.
0:14:45 > 0:14:46Dune ants, on patrol,
0:14:46 > 0:14:48investigate the grass for food...
0:14:51 > 0:14:54..and trigger the spider's warning systems.
0:14:56 > 0:14:57Gotcha!
0:14:59 > 0:15:02Now, the spider uses its tolerance to high temperatures
0:15:02 > 0:15:03to its advantage.
0:15:05 > 0:15:07Pinned to the burning sand,
0:15:07 > 0:15:09the ant overheats rapidly.
0:15:11 > 0:15:13Within seconds,
0:15:13 > 0:15:16the ant's core temperature will have increased by two degrees,
0:15:16 > 0:15:18enough to kill it.
0:15:23 > 0:15:24Using the hot sand
0:15:24 > 0:15:25to do its dirty work
0:15:25 > 0:15:27is a brilliant technique.
0:15:27 > 0:15:29And with food so scarce,
0:15:29 > 0:15:30when it does come along,
0:15:30 > 0:15:32the spider can't afford to miss.
0:15:39 > 0:15:41While some sit and wait,
0:15:41 > 0:15:43others have to hunt for food.
0:15:44 > 0:15:48The sand shows evidence of another bizarre creature that lives here.
0:15:50 > 0:15:51Like its arachnid neighbour,
0:15:51 > 0:15:54it too makes use of the cooler, deeper sand.
0:15:56 > 0:15:59But it takes advantage of the quirk of deserts around the world -
0:15:59 > 0:16:02the days are hot, ferociously hot.
0:16:03 > 0:16:05The nights are cold.
0:16:06 > 0:16:09Temperatures drop by 40 degrees.
0:16:17 > 0:16:20Now, it's cool enough for the golden mole,
0:16:20 > 0:16:22in its thick fur coat,
0:16:22 > 0:16:23to move around.
0:16:24 > 0:16:27Having spent the day deep in the cool sand,
0:16:27 > 0:16:30it emerges to hunt for termites at night.
0:16:34 > 0:16:37Air trapped between the grains allows the mole to breathe,
0:16:37 > 0:16:39but also makes the sand unstable.
0:16:41 > 0:16:44And so, the golden mole leaves no tunnel.
0:16:44 > 0:16:47He is a sand swimmer,
0:16:47 > 0:16:49ploughing through the dunes
0:16:49 > 0:16:51as his trail collapses behind him.
0:16:55 > 0:16:57Despite its appearance,
0:16:57 > 0:17:00this little mammal is not related to our European mole.
0:17:02 > 0:17:05Instead, it's descended from an ancient group of African mammals
0:17:05 > 0:17:09dating back over 40 million years.
0:17:12 > 0:17:16So the mole has had plenty of time to adapt to life in the dunes.
0:17:18 > 0:17:19He is entirely blind.
0:17:22 > 0:17:24Sensible, really -
0:17:24 > 0:17:26eyes would only be damaged by the sand.
0:17:29 > 0:17:34With such little rain, plants are few and far between.
0:17:34 > 0:17:38But termites are most reliably found around plant roots,
0:17:38 > 0:17:40so the mole may have to travel
0:17:40 > 0:17:43over five kilometres a night in search of food.
0:17:44 > 0:17:47Without eyes, how does the mole find its insect prey
0:17:47 > 0:17:49in this featureless desert?
0:17:54 > 0:17:57Well, grasses blowing in the wind
0:17:57 > 0:17:59send percussive vibrations
0:17:59 > 0:18:00through the sand.
0:18:02 > 0:18:03The golden mole
0:18:03 > 0:18:06has an extraordinarily developed middle ear bone -
0:18:06 > 0:18:10proportionally, 6,000 times bigger than our own.
0:18:10 > 0:18:13It's not sight, but sound
0:18:13 > 0:18:16that guides this remarkable little mammal.
0:18:18 > 0:18:22It can detect the slightest movement of grass or insect.
0:18:25 > 0:18:27By dipping his head into the sand,
0:18:27 > 0:18:30the mole uses his super hearing
0:18:30 > 0:18:31to navigate between grass clumps...
0:18:34 > 0:18:36..and secure himself a meal.
0:18:48 > 0:18:51It is perfectly evolved for hunting in the sand.
0:18:58 > 0:18:59Well, most of the time.
0:19:05 > 0:19:08And so, all of the Namibian desert's inhabitants
0:19:08 > 0:19:12have developed unique ways in which to deal with this microworld.
0:19:14 > 0:19:16But these adaptations
0:19:16 > 0:19:18by the insects, reptiles and mammals
0:19:18 > 0:19:21are because of this extreme environment.
0:19:21 > 0:19:24Clever avoidance tactics, yes,
0:19:24 > 0:19:27but not the reason why this system works.
0:19:28 > 0:19:32It's not enough just to avoid the climate.
0:19:32 > 0:19:34In order for an ecosystem to sustain,
0:19:34 > 0:19:38its animals and plants must live long enough to grow, to reproduce.
0:19:40 > 0:19:44And to do that, they MUST have water.
0:19:44 > 0:19:47It's one of the most fundamental elements of life.
0:19:48 > 0:19:50So where is it in this desert?
0:19:56 > 0:20:00Well, the Namib is harbouring a life-giving secret.
0:20:01 > 0:20:04The key to this puzzle has been created
0:20:04 > 0:20:05by a meteorological quirk
0:20:05 > 0:20:07as old as the desert itself.
0:20:09 > 0:20:10Like our golden mole,
0:20:10 > 0:20:15the secret to this desert success avoids the day's heat.
0:20:18 > 0:20:20It comes by night.
0:20:22 > 0:20:25Fog creeps through the dunes.
0:20:27 > 0:20:31But a dense fog in one of the most arid environments on Earth -
0:20:31 > 0:20:33how is this possible?
0:20:35 > 0:20:38Well, the ocean knows.
0:20:39 > 0:20:41The freezing cold currents
0:20:41 > 0:20:44that support those seals and pound the Namib coast
0:20:44 > 0:20:48have another role to play in life in the interior.
0:20:50 > 0:20:51The cold, wet, heavy air
0:20:51 > 0:20:55riding the winds above these currents meet the land
0:20:55 > 0:20:58and are forced under the drier and lighter air from the desert.
0:21:01 > 0:21:04Under normal atmospheric conditions,
0:21:04 > 0:21:06cold air would sit high in the atmosphere,
0:21:06 > 0:21:09above the warmer surface air.
0:21:09 > 0:21:11Instead, these layers are reversed.
0:21:13 > 0:21:15This quirk is known as an inversion layer.
0:21:18 > 0:21:23Once trapped, the moisture within this cold layer forms a dense mist.
0:21:25 > 0:21:27And it's this mist, this sea fog
0:21:27 > 0:21:31that forms the life blood of the Namib Desert.
0:21:35 > 0:21:39For fog is, in its essence, just suspended water,
0:21:39 > 0:21:41an airborne reservoir.
0:21:41 > 0:21:45You just need to know how to harvest it.
0:21:45 > 0:21:48The few plants drip with it.
0:21:48 > 0:21:51The desert crickets drink it from their stems.
0:22:01 > 0:22:03A gecko collects water droplets
0:22:03 > 0:22:07that have condensed on its warm eyeballs.
0:22:09 > 0:22:13The sidewinding adder licks water droplets from its skin.
0:22:19 > 0:22:22But perhaps the cleverest adaptation of all
0:22:22 > 0:22:24can be attributed to a beetle
0:22:24 > 0:22:26or, more accurately, to its back.
0:22:28 > 0:22:30The settling fog triggers
0:22:30 > 0:22:32the most unusual beetle behaviour.
0:22:34 > 0:22:37They're not known as fog baskers without a reason.
0:22:39 > 0:22:43They emerge from the sand in the early mornings
0:22:43 > 0:22:45and, by standing on their heads,
0:22:45 > 0:22:48present their backs to the rolling fog.
0:22:48 > 0:22:51The beetle's back is riddled
0:22:51 > 0:22:53with peaks that attract the fog,
0:22:53 > 0:22:56encouraging droplets to form
0:22:56 > 0:22:58which then roll down waxy troughs
0:22:58 > 0:23:00into their open mouths.
0:23:03 > 0:23:08This peculiar water harvesting tactic is highly productive.
0:23:09 > 0:23:12By the time the fog has been broken by the sun,
0:23:12 > 0:23:14a beetle might have consumed
0:23:14 > 0:23:1640% of its body weight in water.
0:23:20 > 0:23:22This fog is reliable enough
0:23:22 > 0:23:26to allow the beetles to keep topping up with this vital fluid...
0:23:28 > 0:23:30..becoming like walking water bottles
0:23:30 > 0:23:32to other thirsty dune dwellers.
0:23:33 > 0:23:36And forming the base of a complex fog web
0:23:36 > 0:23:41in which water is passed through the ecosystem from prey to predator.
0:23:45 > 0:23:48The beetle provides the chameleon
0:23:48 > 0:23:50with enough water to live on
0:23:50 > 0:23:52for several days.
0:23:58 > 0:23:59The sidewinding adder,
0:23:59 > 0:24:01a master of desert camouflage,
0:24:01 > 0:24:03is also on the hunt for water.
0:24:10 > 0:24:12Eyes positioned on top of its head
0:24:12 > 0:24:15allow the adder to bury itself in the sand,
0:24:15 > 0:24:18becoming almost completely invisible.
0:24:22 > 0:24:24The adder may have to lie in wait for several hours
0:24:24 > 0:24:26before the right target appears.
0:24:30 > 0:24:32By twitching the tip of its tail,
0:24:32 > 0:24:34the snake mimics a small insect in distress.
0:24:34 > 0:24:37The perfect lure
0:24:37 > 0:24:39for a nearby lizard.
0:24:39 > 0:24:41The lizard,
0:24:41 > 0:24:43full of water from the morning fog,
0:24:43 > 0:24:44becomes a precious resource
0:24:44 > 0:24:45to larger predators.
0:24:52 > 0:24:54The adder is quick...
0:24:56 > 0:24:58..but, on this occasion,
0:24:58 > 0:24:59the lizard is faster.
0:25:05 > 0:25:10So these fog harvesters act as both a food and water source
0:25:10 > 0:25:11in this arid environment.
0:25:14 > 0:25:17But, if these are the very bottom rung of the food chain,
0:25:17 > 0:25:19what are they eating to survive?
0:25:21 > 0:25:22In other ecosystems,
0:25:22 > 0:25:26plants provide the most basic food source.
0:25:26 > 0:25:27But, even with the fog,
0:25:27 > 0:25:30the sand is too dry and unstable
0:25:30 > 0:25:33to support any but the hardiest of plants
0:25:33 > 0:25:35and they're not in sufficient numbers
0:25:35 > 0:25:37to support this amount of life.
0:25:39 > 0:25:42The Namib Desert has another trick up its sleeve.
0:25:46 > 0:25:49The winds that bring the fog also bring another lifeline.
0:25:52 > 0:25:55They blow in bits of dead plants,
0:25:55 > 0:25:57the odd insect and droppings,
0:25:57 > 0:26:00known collectively as detritus,
0:26:00 > 0:26:02which is deposited on the dunes.
0:26:04 > 0:26:06This collection of environmental scraps
0:26:06 > 0:26:08may not seem like rich pickings,
0:26:08 > 0:26:11but, for the species that form the lowest rung of the food chain,
0:26:11 > 0:26:13it's manna from heaven.
0:26:19 > 0:26:22Fog-basking beetles are detritovores,
0:26:22 > 0:26:25feeding on dead and decomposing organic matter.
0:26:25 > 0:26:28But this is fast food.
0:26:28 > 0:26:30The beetles must work quickly
0:26:30 > 0:26:33before their meal is once more blown away by the winds.
0:26:38 > 0:26:40And so, when they, in turn, are consumed,
0:26:40 > 0:26:43the energy from the detritus will be transferred to the predator,
0:26:43 > 0:26:46making the success
0:26:46 > 0:26:48of this entire ecosystem
0:26:48 > 0:26:50dependent on the winds
0:26:50 > 0:26:52that blow across this amazing land.
0:26:58 > 0:27:02At first glance, Namibia's coastal desert might seem lifeless...
0:27:07 > 0:27:09..but by looking closely
0:27:09 > 0:27:10and examining the life here,
0:27:10 > 0:27:12in this microworld,
0:27:12 > 0:27:14where species succeed
0:27:14 > 0:27:16because of their unique adaptations
0:27:16 > 0:27:18that protect them against
0:27:18 > 0:27:21the very climate in which they live.
0:27:23 > 0:27:26We've discovered the true secret to life.
0:27:26 > 0:27:29Not in the desert itself,
0:27:29 > 0:27:31not in the structure of the dunes
0:27:31 > 0:27:33or hidden in the coastal sands.
0:27:34 > 0:27:39This ecosystem relies entirely on external forces.
0:27:41 > 0:27:43Without cold ocean currents
0:27:43 > 0:27:45and the winds that rush along this coast
0:27:45 > 0:27:48bringing the key ingredients for life,
0:27:48 > 0:27:50this desert would be truly barren.
0:27:52 > 0:27:55Instead, animals forge an existence here
0:27:55 > 0:27:56that cannot be found
0:27:56 > 0:27:58anywhere else on the planet.
0:28:02 > 0:28:06The secret to survival is in the very air of the Namib Desert...
0:28:08 > 0:28:10..and the extraordinary creatures
0:28:10 > 0:28:12that have evolved to harvest it.
0:28:52 > 0:28:56Subtitles by Red Bee Media Ltd