It's approaching midday.
A fringe-toed lizard is hungry.
He's on a stakeout.
Flashy scales reflect some of the sun's rays.
Nevertheless, the heat is almost unbearable.
His prey hasn't left home all day.
The lizard is the last animal still out on the dunes.
But even he can't take it anymore.
To survive longer, you'd need a space suit.
And in a way, that's what these insects have.
Silver ants' armored skin reflects light.
They can tolerate temperatures that would kill any other land animal.
Even so, they can only survive for less than 10 minutes in the midday sun.
The ants race to find food as soon as their predators go to ground.
They can't afford to waste a second getting lost, so they spin to take a bearing from the sun.
They log every change of direction, every footstep, in order to know exactly where they are and where their nest lies.
Only four minutes to spare and they've found a victim of heatstroke.
A meal.
But it's going to take a monumental effort to get it home.
Three minutes to go and they're nearing their maximum temperature, an astounding 53 degrees Celsius.
But there are already casualties.
One minute left and they're not going to make it.
Something has to change. a lone, creviced zebra.
He weighs close to half a ton and could go for three days without drinking.
Like the macaques, his forebears were refugees from the advancing Sahara.
The land is scrubby and dry.
But this stallion has claimed it as his own.
He's been waiting months for visitors, female visitors.
If they like his territory, they might stay a while.
It's his first chance to mate for a very long time.
Hardly a success.
Perhaps his visitors are looking for a more impressive partner.
There's another setback.
The females were being followed, a posse of young males.
Everyone a rival.
It's time to separate the men from the boys.
One by one, the stallion sees them off.
The females had ringside seats.
And his prowess has not gone unnoted.
Machismo gives way to Tentenus.
This oasis is fed by a hot volcanic spring.
Slightly away from the stream of near-boiling water, it's cooler and fish can live.
These are tilapia.
Hatchlings stick close to their mother.
There are other dangers here beside the scalding water, particularly at night.
And the tilapia are almost blind in the darkness.
In panic, they all leap to escape the hunter's approach.
But this female can't abandon her brood.
The crocodiles won't be thwarted.
They too can leap.
With first light, the crocodiles lose the element of surprise, and the battle is over for now.
The mother fish has survived, but where are her young?
All present and correct.
They spent the whole night sheltering in her mouth.
The contest will be repeated at sunset.
There is nowhere else to go.
These bizarre little birds are baby ostriches. for desert survivors.
But in the Kalahari, these early days are perilous.
Like leopards and meerkats, adult ostriches can extract all the moisture they require from their food.
The chicks, however, won't survive much more than another day without water.
But there's none in sight.
How can their parents conjure up water out here?
The youngsters follow their parents as they head out onto a featureless wasteland.
It seems like a suicidal journey.
The Etosha salt pan.
Here, water is more often a mirage than reality.
It's now well over 40 degrees centigrade.
Their father shades his chicks from the midday sun.
Another mirage?
No, the ostrich family is not alone out here.
Surrounded by the vast expanse of sun-baked mud, sweet, fresh water wells up from deep below ground.
Like a miracle. lies a secret.
One that was discovered only 25 years ago.
Humid air rushing to the surface gives this place its name, Dragon's Breath Cave.
The shaft descends for 60 meters until it meets...
Here there is a massive chamber big enough to swallow three jumbo jets, nose to tail filled with cool, fresh water.
The world's largest underground lake.
This is fossil water.
It's been trapped here undisturbed for thousands, if not millions, of years.
We have no idea how deep the lake is.
Divers have been down to 100 meters, and still there's no sign of the bottom.
Remarkably, dragon's breath is part of a vast cave system that extends beneath the Kalahari for thousands of kilometers.
Even here, in this lonely cave, Golden catfish, only found in this one cave.
They're the rarest and most isolated fish in the world.
Life down here is as challenging as it is in the desert above.
There's no food, except the debris that occasionally falls onto the surface.
And these catfish are totally blind.
The only world they know is the one they sense through touch.
A blind fish living in perpetual darkness, deep beneath one of the most arid regions of Africa.
The old bull won't tolerate a rival.
Pushing and shoving, they size each other up.
The young rival seems to think he has a chance and attacks.
The first few blows usually settle things in such battles, but here the stakes are high.
To lose means exile in the desert.
Neither will back down.
As the fight intensifies, they change tactics.
The young male aims for the rump.
The old bull targets his rival's legs.
The old bull is down.
Is this the end of his reign?
He knows a knockout blow is coming.
But the old bull ducks.
And strikes a blow to his rival's underbelly.
Out for the count.
The old bull is victorious.
But only just.
There's a secret to surviving in this world.
It's right in front of him.
Brine flies, salt specialists.
They pass the salt out of their bodies, leaving them sweet and juicy.
All the lizard needs to do is catch them.
To get the equivalent of a teaspoon of fresh water, he has to eat 400 flies.
This fly ridden shoreline is a paradise.
And that's the problem.
There's a new guy in town.
And this territory isn't big enough for the both of them.
The defender puffs himself up.
Perhaps looking larger than life will make the intruder back down.
Owning a stake in this shoreline is the difference between life and death.
Bad news for the intruder.
For the victor, the prize is an endless supply of flies.
And many animals here choose the simplest option of all staying hidden all day and only venturing out in the cool of the night.
As darkness falls, animals appear from seemingly nowhere.
And among them, inevitably, are hunters.
One of the most voracious nocturnal predators is also one of the hardest to see.
This mysterious creature hardly ever appears on the surface of the dunes.
But there are signs on the sand that can give it away.
It lives only here, where the sand grains are so perfectly dry and polished that they flow almost like water.
It's no bigger than a ping-pong ball.
A golden mole.
It's totally blind.
But there's nothing to see underground anyway.
Instead, it has superb hearing.
Its entire head acts as an amplifier that picks up vibrations through the sand.
So to locate prey on the surface of the dune, it has paradoxically, to thrust its face into the dune not easy to catch when you're blind.
Far better to go into stealth mode.
Once below the sand, it can detect the slightest movement, allowing it to strike with pinpoint accuracy.
Well, most of the time.
It can travel a kilometer a night in search of its dinner.
And right now, it has just detected its main course.
Little wonder it's sometimes called the Shark of the Dunes.
It's July in the deserts of Nevada in the western United States.
The hottest time of the year.
Bands of wild horses, mustang, are converging on one of the last remaining water holes around.
Now water not only offers them the chance to drink, it can also bring power.
If a stallion can control access to water, he will have secured mating rights to the entire herd.
So stallions try to dominate these pools, fighting off rivals who venture too close.
A stranger.
He's traveled 15 kilometers to be here because the pools where he's come from have already dried up.
With him come his females.
If he can't provide them with water, they will leave him for the White Stallion who already dominates this pool.
So he will have to fight.
A broken leg or a shattered jaw would mean a slow and painful death.
A missed kick, and it's all over.
The new arrival has won.
And his prize is more than just a chance to drink.
He has provided for his herd, and in the process, stolen his rival females.
The White Stallion's rule is over.
And now the snakes are on the alert.
This is the best feeding opportunity they will get all year.
On flat ground, a baby iguana can outrun a racer snake.
But others are waiting in ambush.
Another hatchling has its first glimpse of a dangerous place.
A snake's eyes aren't very good, but they can detect movement.
So if the hatchling keeps its nerve, it may just avoid detection.
A near miraculous escape.
The lucky survivors could begin learning the unique way of life demanded by this hostile island.
