0:00:02 > 0:00:03No matter how well we think we know our planet,
0:00:03 > 0:00:06the natural world still has the ability to
0:00:06 > 0:00:10surprise us, to shock us, and maybe sometimes even to scare us
0:00:10 > 0:00:14with its extraordinary events and bizarre behaviour.
0:00:14 > 0:00:17And new technology means that nature's weirdest phenomena
0:00:17 > 0:00:21are being caught ever more readily on camera.
0:00:21 > 0:00:25So we're going to bring you the strangest stories our world
0:00:25 > 0:00:26has to offer.
0:00:28 > 0:00:30I've never seen anything like that before.
0:00:30 > 0:00:33From bizarre body snatchers...
0:00:35 > 0:00:37And a butterfly blizzard.
0:00:37 > 0:00:39Do you see that, guys?
0:00:41 > 0:00:45With the help of scientists, experts and eye witnesses,
0:00:45 > 0:00:49we are going to try and unravel exactly what on earth is going on.
0:01:12 > 0:01:14So, let's get cracking.
0:01:14 > 0:01:19First up, we reveal some astonishing superpowers - specialist
0:01:19 > 0:01:23skills that help animals succeed in the toughest of environments.
0:01:25 > 0:01:28But our next group of extreme jet-setters prove
0:01:28 > 0:01:33that when it comes to superpowers, size isn't everything.
0:01:36 > 0:01:39In early October 2011, the Denning family
0:01:39 > 0:01:45were hiking through woodland in central Mexico when they became
0:01:45 > 0:01:50part of one of most extraordinary events in the natural world.
0:01:50 > 0:01:53Look at them all. Do you see that, guys?
0:01:54 > 0:01:56Millions of Monarch butterflies.
0:01:56 > 0:01:58Wow!
0:01:58 > 0:02:04A vision in orange, carpeting small stands of pines.
0:02:04 > 0:02:07This is awesome.
0:02:10 > 0:02:13Grant Sonnex found himself at the centre
0:02:13 > 0:02:15of a butterfly blizzard.
0:02:23 > 0:02:27Monarchs in their millions, that descend on very certain areas
0:02:27 > 0:02:32of trees in Mexico and California like clockwork, every year.
0:02:37 > 0:02:41Days before, these trees would have been bare.
0:02:43 > 0:02:47So where have all of these swathes of butterflies come from?
0:02:47 > 0:02:48And why are they here?
0:02:51 > 0:02:54Monarchs can be found throughout the United States,
0:02:54 > 0:02:57wherever their staple food, milkweed, is plentiful.
0:03:00 > 0:03:03This food source can take them as far north as Canada.
0:03:04 > 0:03:09Which, when the seasons change, can be a brutal place for a butterfly.
0:03:12 > 0:03:16Richard Fox has spent years studying the intricacies of butterfly behaviour.
0:03:18 > 0:03:20Basically, it's too cold in the winter time
0:03:20 > 0:03:24across most of the United States and certainly in Canada
0:03:24 > 0:03:26for these butterflies to survive.
0:03:26 > 0:03:30So they've got to move or die.
0:03:30 > 0:03:32The Monarchs are quite literally flying for their lives
0:03:32 > 0:03:34away from the cold north.
0:03:37 > 0:03:40But to reach these warm winter hideouts,
0:03:40 > 0:03:43well, that's a seriously long haul flight.
0:03:45 > 0:03:50These butterflies cover over 2,000 miles,
0:03:50 > 0:03:54and fly for anything up to ten weeks to reach these winter roosts.
0:03:56 > 0:03:59It's the kind of journey usually undertaken by birds
0:03:59 > 0:04:02or great herds of mammals.
0:04:02 > 0:04:05So how does a tiny insect manage it?
0:04:07 > 0:04:10Well, these are butterflies with superpowers.
0:04:11 > 0:04:16We tend to think of butterflies as delicate creatures, blown around by the wind.
0:04:16 > 0:04:18But these Monarchs are serious flying machines.
0:04:18 > 0:04:20They have a brain the size of a pin head
0:04:20 > 0:04:24and yet they are able to navigate across a continent
0:04:24 > 0:04:26and they can fly at very high altitude, indeed people have
0:04:26 > 0:04:28seen them from aeroplane windows.
0:04:31 > 0:04:33And they're not flying blind.
0:04:34 > 0:04:38Monarchs come equipped with some serious in-built GPS.
0:04:40 > 0:04:44They have a time-compensated sun compass.
0:04:44 > 0:04:49In their brains they have a compass which uses
0:04:49 > 0:04:53sunshine as a way of working out north and south.
0:04:53 > 0:04:58And in their antennae, their feelers, they have a clock
0:04:58 > 0:05:01which enables them to take account
0:05:01 > 0:05:03for the passage of the sun across the sky.
0:05:05 > 0:05:07As they travel further south,
0:05:07 > 0:05:10these millions of Monarchs from all over the United States
0:05:10 > 0:05:15are funnelled together by the Gulf Coast and the Rocky Mountains.
0:05:15 > 0:05:19In a good year, it might be 150 million Monarchs.
0:05:19 > 0:05:23And rather than spread throughout the forest, they huddle close
0:05:23 > 0:05:28together, warmth in numbers against the cooler nights.
0:05:29 > 0:05:34But as the sun rises, and the day heats up,
0:05:34 > 0:05:38the butterflies leave the branches in an orange explosion!
0:05:50 > 0:05:54Not surprisingly, these winter roosts have become tourist hotspots.
0:05:57 > 0:06:00And for the people that live in these special areas
0:06:00 > 0:06:03the arrival of the Monarchs is cause for celebration.
0:06:05 > 0:06:09Lori Mannel is the director of the Museum of Natural History,
0:06:09 > 0:06:11in Pacific Grove, California.
0:06:12 > 0:06:17Also known as Butterfly Town USA.
0:06:17 > 0:06:21Pacific Grove takes its Monarchs very seriously.
0:06:29 > 0:06:35The first Saturday of October of every year all the schoolchildren in Pacific Grove gather together
0:06:35 > 0:06:38to welcome the Monarchs back to the town.
0:06:43 > 0:06:46The butterflies are the cultural icon of this town.
0:06:51 > 0:06:54But just how they find the exact spot that their family member
0:06:54 > 0:06:59travelled to the year before is still not fully understood.
0:06:59 > 0:07:03Nor is why they choose these particular stands of trees.
0:07:06 > 0:07:10When it comes to these extraordinary migrators,
0:07:10 > 0:07:14there are still more superpowers left to be discovered.
0:07:20 > 0:07:24That Monarch migration is truly remarkable.
0:07:24 > 0:07:27Did you know that you can witness a similarly Herculean butterfly
0:07:27 > 0:07:29effort here in the UK?
0:07:29 > 0:07:33You see, Painted Ladies like these move from Africa up through
0:07:33 > 0:07:34Europe every summer,
0:07:34 > 0:07:36and end up in our gardens.
0:07:36 > 0:07:39And we used to think that they just died here.
0:07:39 > 0:07:43Recently, however, we've spotted them flying back to Africa.
0:07:43 > 0:07:50So when you take in all of the generations, that's a round trip of more than 9,000 miles.
0:07:50 > 0:07:53Not bad for an insect that weighs less than a gram.
0:07:55 > 0:07:57This next strange substance
0:07:57 > 0:08:00is unlikely to win any popularity contests.
0:08:04 > 0:08:09There's a very sticky situation facing fishermen in the Atlantic.
0:08:09 > 0:08:11How do you get rid of all that slime?
0:08:11 > 0:08:12They're pulling up their nets and pots
0:08:12 > 0:08:16only to find them covered in slime.
0:08:16 > 0:08:18So does it ruin your prawns?
0:08:18 > 0:08:21An oceanic ooze is clogging their nets
0:08:21 > 0:08:24and having to be bailed from boats.
0:08:28 > 0:08:31Armfuls of this colourless goop
0:08:31 > 0:08:34is appearing in any one catch.
0:08:35 > 0:08:37With often more slime than fish,
0:08:37 > 0:08:41removing it from the haul is an absolute nightmare.
0:08:44 > 0:08:48It's too common a complaint to be attributed to some freak event,
0:08:48 > 0:08:50or rare natural phenomena.
0:08:50 > 0:08:53Something is creating enough of this substance
0:08:53 > 0:08:55to drive fishermen crazy.
0:08:55 > 0:08:58The question is, what?
0:09:02 > 0:09:04Well, the source of this mystery mucus
0:09:04 > 0:09:07can be found on the deep sea floor.
0:09:09 > 0:09:12The repugnant perpetrator
0:09:12 > 0:09:14is the hagfish.
0:09:17 > 0:09:20It's the undertaker of the deep,
0:09:20 > 0:09:22searching the murky bed for corpses.
0:09:25 > 0:09:28It uses a rasping tongue to pull flesh from bone.
0:09:31 > 0:09:34It will even wriggle inside a rotting corpse
0:09:34 > 0:09:37to devour the soft flesh under the skin,
0:09:37 > 0:09:41literally eating the victim inside out.
0:09:43 > 0:09:47But nasty eating habits aside, the question remains -
0:09:47 > 0:09:52why would a creature that lives on the seabed need to produce slime?
0:09:54 > 0:09:59Well, aside from its willingness to eat sea-floor scraps,
0:09:59 > 0:10:03the hagfish doesn't seem to have very much going for it.
0:10:03 > 0:10:07It's pretty much blind, has no jaws or tough scales.
0:10:07 > 0:10:09It looks vulnerable.
0:10:12 > 0:10:16But in fact, the hagfish really is quite a success story.
0:10:16 > 0:10:20It's been around for a whopping 300 million years,
0:10:20 > 0:10:24which makes it one of the oldest fishes in the sea.
0:10:24 > 0:10:30And the secret to its success is slime.
0:10:32 > 0:10:34It's a defensive strategy so brilliant
0:10:34 > 0:10:38that it makes the hagfish quite literally untouchable.
0:10:41 > 0:10:46Professor Doug Fudge studies these master slimers.
0:10:48 > 0:10:52So the hagfish is essentially covered with slime glands.
0:10:52 > 0:10:55And when an animal is attacked by a predator,
0:10:55 > 0:10:59there's muscle in the area where it's touched
0:10:59 > 0:11:02that cause those slime glands to release their contents.
0:11:02 > 0:11:05There's actually a little mini volcano of slime
0:11:05 > 0:11:08that comes out of the gland.
0:11:08 > 0:11:10It's reinforced with tens of thousands
0:11:10 > 0:11:14of silk-like protein fibres that we call slime threads
0:11:14 > 0:11:16and it mixes with seawater
0:11:16 > 0:11:19and it forms this large volume
0:11:19 > 0:11:22of very unusual fibre-reinforced slime.
0:11:23 > 0:11:29A single hagfish can turn a bucket of water into slime in seconds.
0:11:29 > 0:11:32Eww, that is so gross.
0:11:33 > 0:11:37Which proves to be a pretty fantastic underwater weapon.
0:11:37 > 0:11:41In a recent study that was published by a group in New Zealand
0:11:41 > 0:11:46they showed hagfish using their slime in a wild situation.
0:11:47 > 0:11:51The fibrous mucus is designed to choke a predator
0:11:51 > 0:11:53by clogging up its airways.
0:11:53 > 0:12:00The shark is left gagging as its gills fill with mucus.
0:12:01 > 0:12:06Every assailant is repulsed by a wall of slime.
0:12:07 > 0:12:09And the technique is so effective
0:12:09 > 0:12:13that the hagfish seems utterly unperturbed by the assault.
0:12:15 > 0:12:18So both predators and unsuspecting fishermen
0:12:18 > 0:12:20are getting the same treatment.
0:12:20 > 0:12:24But how does the hagfish prevent itself from becoming
0:12:24 > 0:12:27the victim of its own slimy strategy?
0:12:27 > 0:12:31They have an ingenious way of getting out of the slime.
0:12:32 > 0:12:35They'll tie their body in an overhand knot
0:12:35 > 0:12:40and then pass their body through the knot,
0:12:40 > 0:12:44and that'll wipe the slime off their body.
0:12:47 > 0:12:52A necessary skill for the ocean's most slippery character.
0:12:56 > 0:13:01Now you may not like this, but humans produce slime, too.
0:13:01 > 0:13:04In the form of snot.
0:13:04 > 0:13:08And what's remarkable is that hagfish slime and human snot
0:13:08 > 0:13:11are actually composed of very similar proteins.
0:13:11 > 0:13:16Now hagfish use their slime to protect themselves from predators
0:13:16 > 0:13:20and humans use their snot to trap harmful substances
0:13:20 > 0:13:22and then expel them from the body.
0:13:22 > 0:13:26So when you think about it, both hagfish and humans
0:13:26 > 0:13:29are using slime as a front-line defence.
0:13:30 > 0:13:34These animals have proved that in the natural world,
0:13:34 > 0:13:37it pays to be a master craftsman.
0:13:38 > 0:13:42Whether you're a silk spinner escaping the rising tide,
0:13:42 > 0:13:47a slime producer defending yourself from attack,
0:13:47 > 0:13:51or a sand sculptor looking for love,
0:13:53 > 0:13:56a super structure is crucial to success.
0:14:01 > 0:14:05So a specialist skill can help an animal get ahead,
0:14:05 > 0:14:09but what if you just can't survive on your own?
0:14:09 > 0:14:14Rather than admit defeat, this next selection of weirdness
0:14:14 > 0:14:18shows that enlisting some help can hold the key.
0:14:18 > 0:14:22There's a strange subterranean structure
0:14:22 > 0:14:24created by remarkable teamwork.
0:14:26 > 0:14:31But first, a chilling tale of some real-life zombies.
0:14:33 > 0:14:36Eric Williams from Delaware was mopping his kitchen floor
0:14:36 > 0:14:40when a dead beetle began to mutate in front of his eyes.
0:14:44 > 0:14:48From its body, something long and wormlike was emerging.
0:14:52 > 0:14:56And Eric wasn't the only one to witness this miniature horror.
0:14:56 > 0:14:59No idea what those things are.
0:14:59 > 0:15:02I see all these strange hairs moving around.
0:15:02 > 0:15:03What do you think that is?
0:15:03 > 0:15:05It's a cockroach.
0:15:05 > 0:15:06Look at the string coming out of it.
0:15:06 > 0:15:08Oh, my God!
0:15:08 > 0:15:11All of these records had that one thing in common.
0:15:11 > 0:15:14Be it a mopped floor or nearby puddle,
0:15:14 > 0:15:18the presence of water was triggering these writhing worms.
0:15:18 > 0:15:20That's disgusting.
0:15:20 > 0:15:23But what were they,
0:15:23 > 0:15:26and how had they got into the bodies of these insects?
0:15:28 > 0:15:31Biologist Janice Moore has spent a lifetime
0:15:31 > 0:15:34fascinated by this particular weird event.
0:15:37 > 0:15:40Whenever I was a child I used to see these long worms
0:15:40 > 0:15:44sort of squiggling around my grandfather's horse trough.
0:15:44 > 0:15:47And I was told they were horsehair worms,
0:15:47 > 0:15:49and that is their common name
0:15:49 > 0:15:53because legend has it that these worms come from horse hairs.
0:15:53 > 0:15:56Well, in reality, they're parasites, and they're parasites
0:15:56 > 0:16:00of crickets, grasshoppers, that sort of animal.
0:16:00 > 0:16:04These parasites live inside, say, the cricket,
0:16:04 > 0:16:07and grow up to be huge compared to the cricket.
0:16:07 > 0:16:10All coiled up. The cricket is almost total parasite.
0:16:11 > 0:16:16The hairworm larva develops snug inside the host insect's body.
0:16:17 > 0:16:20But to complete the life cycle, it has to breed,
0:16:20 > 0:16:23and to do this it needs to find water.
0:16:24 > 0:16:28And rather than leave the safety of the host,
0:16:28 > 0:16:29the hairworm has no qualms
0:16:29 > 0:16:32with making the poor insect do all of the legwork.
0:16:34 > 0:16:39This fiendish parasite alters the host's behaviour.
0:16:39 > 0:16:41So at that point the cricket
0:16:41 > 0:16:44becomes almost suicidally attracted to water.
0:16:44 > 0:16:47And they've been reported to jump into toilets,
0:16:47 > 0:16:49into dog watering bowls.
0:16:49 > 0:16:51And if the hairworm's big enough,
0:16:51 > 0:16:56the merest hint of moisture can be enough to tempt it out.
0:16:56 > 0:17:00- What is it?- I have never seen anything like that before.
0:17:00 > 0:17:04Keep an eye out for these miniature body snatchers,
0:17:04 > 0:17:07because they're found here in the UK too.
0:17:09 > 0:17:14In fact, in every corner of the globe, super sneaky parasite species
0:17:14 > 0:17:17have found ways to get others to do the hard work for them.
0:17:20 > 0:17:25For example, the mind controller that lurks in German gardens.
0:17:25 > 0:17:27So there's a really fun parasite.
0:17:27 > 0:17:30The scientific name is Leucochloridium.
0:17:30 > 0:17:34And it actually lives in the intestinal tract
0:17:34 > 0:17:36of a variety of songbirds.
0:17:36 > 0:17:39The parasitic flatworm reaches maturity
0:17:39 > 0:17:42inside the digestive system of the bird
0:17:42 > 0:17:46and casts out its eggs in the bird's droppings.
0:17:46 > 0:17:49This would be the end of the cycle for Leucochloridium
0:17:49 > 0:17:51if it weren't for the garden snail
0:17:51 > 0:17:54that finds bird droppings irresistible.
0:17:54 > 0:17:56When they eat these eggs,
0:17:56 > 0:18:00the egg hatches and the little larval parasite,
0:18:00 > 0:18:02a flatworm called a trematode,
0:18:02 > 0:18:05moves into the tentacles of the snail.
0:18:05 > 0:18:10And there it grows up into a kind of striped mass.
0:18:12 > 0:18:15The snail's tentacle is now one enormous,
0:18:15 > 0:18:18pulsating flatworm brood sac.
0:18:20 > 0:18:24But here our parasitic mastermind encounters a problem.
0:18:24 > 0:18:29Just like the hairworm, it can't breed in the snail.
0:18:29 > 0:18:31To lay its eggs, it once again
0:18:31 > 0:18:34needs to be back inside a bird's intestinal tract.
0:18:34 > 0:18:38So how does the fickle flatworm complete the cycle?
0:18:39 > 0:18:40Mind control.
0:18:42 > 0:18:47It forces the usually reclusive snail upward toward the light.
0:18:48 > 0:18:54Once exposed, the snail's tentacle is a pulsating grub on a plate.
0:18:55 > 0:18:58Birds will look at this and say, "A-ha! Good to eat!"
0:18:58 > 0:19:00and they'll eat it.
0:19:02 > 0:19:06And in that way, the life cycle is complete.
0:19:07 > 0:19:10Now, the poor snail is the middleman,
0:19:10 > 0:19:14it might just get out alive - minus a tentacle.
0:19:14 > 0:19:16But other hosts are not so lucky.
0:19:18 > 0:19:22Our next parasite requires its host to make the ultimate sacrifice.
0:19:24 > 0:19:28So one of the most spectacular examples of zombie behaviour
0:19:28 > 0:19:30is that of ants infected with a fungus.
0:19:32 > 0:19:36If you're battling for space in the rainforest,
0:19:36 > 0:19:38hitching a ride on the back of an ant would seem
0:19:38 > 0:19:40to be a clever tactic.
0:19:40 > 0:19:43But it's not nearly clever enough for the cordyceps fungus,
0:19:43 > 0:19:46which is a bit of a control freak -
0:19:47 > 0:19:49mind control, that is.
0:19:51 > 0:19:54The fungus enters the body through the ant's windpipe
0:19:54 > 0:19:59where it begins to extract nutrients from all but its major organs.
0:19:59 > 0:20:03As the fungus grows, it eats the ant alive,
0:20:03 > 0:20:06whilst leaving it with just enough of its faculties to move.
0:20:09 > 0:20:13And the reason why it does this is brilliantly devious.
0:20:16 > 0:20:20To cast spores, the fungus needs to be high.
0:20:20 > 0:20:23So it floods the ant's brain with chemicals,
0:20:23 > 0:20:25forcing it on an upward march.
0:20:27 > 0:20:29Having reached an optimum height,
0:20:29 > 0:20:34the ant has served its purpose and cordyceps devours its brain.
0:20:36 > 0:20:38Before, with a final flourish,
0:20:38 > 0:20:43it bursts through the exoskeleton and casts spores into the air.
0:20:44 > 0:20:47It's really a wonderful story if you happen to be reading about it
0:20:47 > 0:20:49and a really nasty story if you happen to be an ant.
0:20:54 > 0:20:56One of my favourite types of bodysnatcher
0:20:56 > 0:20:58actually lives in UK waters.
0:20:58 > 0:21:03The larvae of a species of tapeworm inhabits the stickleback.
0:21:03 > 0:21:06And just like all the other parasites we've been looking at,
0:21:06 > 0:21:10when it needs to breed, it needs another host - in this case, birds.
0:21:10 > 0:21:14Quite obviously, it doesn't leap out of the mouth of the stickleback
0:21:14 > 0:21:16into a passing bird. No.
0:21:16 > 0:21:19What it does is very cleverly modify the stickleback's behaviour,
0:21:19 > 0:21:22causing it to flip over onto its back
0:21:22 > 0:21:24and reveal its bright white belly,
0:21:24 > 0:21:28making it far more obvious to predators like herons.
0:21:31 > 0:21:34I know it's a sad end for the old stickleback,
0:21:34 > 0:21:36but you've got to admit that when it comes to parasites,
0:21:36 > 0:21:40mind control is a fiendishly effective survival technique.
0:21:42 > 0:21:45Bending the will of others for your own gain
0:21:45 > 0:21:49is not exactly the most altruistic of survival methods.
0:21:49 > 0:21:53Thankfully, our next story shows you just what can be achieved
0:21:53 > 0:21:55when you choose to work together.
0:21:57 > 0:22:02In May 2004, a group of scientists gathered in South America.
0:22:02 > 0:22:05At a very particular spot in rural Brazil
0:22:05 > 0:22:09they took up tools and began to dig.
0:22:12 > 0:22:17Over the next few days, they painstakingly excavated the area.
0:22:20 > 0:22:24And from the soil, something incredible began to emerge.
0:22:26 > 0:22:29They uncovered a vast network,
0:22:31 > 0:22:34some 50 metres squared,
0:22:35 > 0:22:39an architectural maze of different shapes and structures
0:22:39 > 0:22:42branching out into the ground.
0:22:42 > 0:22:46This subterranean design was precise,
0:22:46 > 0:22:50and too complex to have been created by chance.
0:22:50 > 0:22:52It had been engineered.
0:22:54 > 0:22:55But by what?
0:22:57 > 0:23:00What could have created this underground architecture?
0:23:05 > 0:23:09What the scientists had uncovered was a secret city.
0:23:11 > 0:23:15A giant home created for some of the smallest animals on the planet.
0:23:17 > 0:23:19Ants.
0:23:21 > 0:23:24For ant biologists like Ross Kirby,
0:23:24 > 0:23:27this experiment brought theory to life.
0:23:27 > 0:23:30This is the first time that we can literally
0:23:30 > 0:23:32see the bare bones of what they've actually built.
0:23:32 > 0:23:37They poured ten tonnes of cement into an empty leaf-cutter nest
0:23:37 > 0:23:40over the course of three days.
0:23:40 > 0:23:42And once this cement had set,
0:23:42 > 0:23:46the scientists could cut away and reveal the underground metropolis
0:23:46 > 0:23:49of this leaf-cutter ant kingdom.
0:23:49 > 0:23:53This wasn't just your average ant nest.
0:23:53 > 0:23:56This was an entire ant city,
0:23:56 > 0:24:00going as deep as eight metres into the ground
0:24:00 > 0:24:03and masterminded by an estimated population
0:24:03 > 0:24:07of up to seven million leaf-cutter ants.
0:24:08 > 0:24:13But why does an ant need such an impressively complex home?
0:24:13 > 0:24:16There's brood chambers which are important
0:24:16 > 0:24:18because this is where the eggs develop.
0:24:18 > 0:24:20There's waste disposal chambers.
0:24:20 > 0:24:22There's also many different tunnels,
0:24:22 > 0:24:25not just to take the ants from chamber to chamber,
0:24:25 > 0:24:26but also to allow air
0:24:26 > 0:24:29to be completely circulated throughout the nest.
0:24:29 > 0:24:32Ants use pheromones to organise construction work
0:24:32 > 0:24:36and to guide them to and from foraging sites.
0:24:36 > 0:24:39These chemical trails help them work efficiently
0:24:39 > 0:24:42and stop them from getting lost.
0:24:42 > 0:24:46They ensure a steady stream of grass into the nest.
0:24:46 > 0:24:48But it's not to eat.
0:24:49 > 0:24:53The ants can't digest grass.
0:24:53 > 0:24:56Instead, they use the blades to feed a fungus,
0:24:56 > 0:24:59cultivated in special garden chambers.
0:25:01 > 0:25:04This fungus is the ants' preferred main meal,
0:25:04 > 0:25:08and when you've got seven million mouths to feed,
0:25:08 > 0:25:10that's a lot of fungus farming.
0:25:11 > 0:25:17A nest needs to be this size to support such a large colony.
0:25:17 > 0:25:21But it's almost inconceivable that something as small
0:25:21 > 0:25:26and simple as an ant could have created such an amazing structure.
0:25:28 > 0:25:30When looking at an entire ant colony,
0:25:30 > 0:25:34you shouldn't be thinking of it as seven million different individuals,
0:25:34 > 0:25:37it should be thought of as one great collective unit.
0:25:39 > 0:25:42A single ant by itself isn't really up to much.
0:25:42 > 0:25:44However, when you get up to seven million of them,
0:25:44 > 0:25:47interacting together, their behaviour can be quite complex.
0:25:49 > 0:25:53All of these ants working together for the good of the whole colony
0:25:53 > 0:25:58transform from individuals into a single living being.
0:25:59 > 0:26:06A super organism. One brain, seven million ants strong.
0:26:06 > 0:26:11It's this organisation that makes one of the smallest animals
0:26:11 > 0:26:14capable of such incredible engineering.
0:26:18 > 0:26:22So, clearly, being part of a super organism is beneficial.
0:26:22 > 0:26:26But a group mentality can also have its drawbacks.
0:26:27 > 0:26:31Kayla Brown was travelling through Peru in June 2008
0:26:31 > 0:26:34when she came across some ants behaving strangely.
0:26:36 > 0:26:41These army ants were spinning round and round in a constant circle.
0:26:41 > 0:26:43Kayla watched them spiralling for hours.
0:26:44 > 0:26:49Before, one by one, the ants began to collapse and die.
0:26:49 > 0:26:52And she wasn't the only one to have witnessed these peculiar
0:26:52 > 0:26:54death circles.
0:26:54 > 0:26:58But why were the usually organised ants on self-destruct?
0:27:00 > 0:27:03Well, it's most likely that these ants were out foraging
0:27:03 > 0:27:06when they got separated from the rest of their party.
0:27:07 > 0:27:10With the pheromone trail lost, the ants began to panic
0:27:10 > 0:27:12and follow each other's pheromones.
0:27:14 > 0:27:17This confused game of Follow My Leader forced them
0:27:17 > 0:27:19into a never-ending circle.
0:27:21 > 0:27:25And because ants aren't programmed to think like individuals,
0:27:25 > 0:27:28they didn't save themselves.
0:27:28 > 0:27:32Instead, the circle became tighter and faster
0:27:32 > 0:27:35until the ants simply died of exhaustion.
0:27:37 > 0:27:42Thankfully, these ant death circles are relatively rare events.
0:27:42 > 0:27:46Clearly proving that the benefits of teamwork must outweigh
0:27:46 > 0:27:48the potential for disaster.
0:27:48 > 0:27:52And of course, ants aren't the only animals that form super organisms.
0:27:52 > 0:27:54Take bees, for example.
0:27:54 > 0:27:56For a hive to be successful,
0:27:56 > 0:28:01thousands of bee brains must work together tirelessly and selflessly.
0:28:01 > 0:28:04And the benefits are security, bed and board.
0:28:04 > 0:28:06Clearly, when it comes to super organisms,
0:28:06 > 0:28:08great minds must think alike.
0:28:11 > 0:28:15These stories show the importance of enlisting some help.
0:28:15 > 0:28:18Whether it's a devious parasite controlling
0:28:18 > 0:28:20a host against its will...
0:28:20 > 0:28:24or an ant colony combining forces to build
0:28:24 > 0:28:26a subterranean megatropolis.
0:28:28 > 0:28:32Two brains, or seven million if you can manage it, are better than one.
0:28:34 > 0:28:35So there we are.
0:28:35 > 0:28:39We've delved into a catalogue of the most fun, the most foul,
0:28:39 > 0:28:42the most morbid and marvellous stories
0:28:42 > 0:28:43that our planet has to offer.
0:28:43 > 0:28:46And whether it's been bizarre animal behaviour
0:28:46 > 0:28:48or weird natural phenomena,
0:28:48 > 0:28:53it's had the very best of our brains completely baffled.
0:28:53 > 0:28:56But then, given the natural world's ability to astound,
0:28:56 > 0:29:01this only really leaves us with one final and inevitable question.
0:29:01 > 0:29:03What next?