0:00:03 > 0:00:05Planet Earth.
0:00:06 > 0:00:08Millions of species.
0:00:11 > 0:00:13But a few are special.
0:00:17 > 0:00:18Thriving.
0:00:20 > 0:00:21Dominating.
0:00:27 > 0:00:29These are the opportunists.
0:00:33 > 0:00:34The collaborators.
0:00:38 > 0:00:39The survivors.
0:00:42 > 0:00:45So, what makes these animals so successful?
0:00:48 > 0:00:52In this series, we'll delve deep beneath the skin,
0:00:52 > 0:00:56to reveal the unique features that set some species apart.
0:01:00 > 0:01:04New behaviour and the very latest scientific discoveries
0:01:04 > 0:01:09will offer fresh insight into the wonder of animals.
0:01:29 > 0:01:32One group of animals has truly colonised the Earth.
0:01:38 > 0:01:41They number more than 100 trillion.
0:01:45 > 0:01:49And consume more meat than all the lions...
0:01:52 > 0:01:53..the tigers...
0:01:56 > 0:01:58..and the wolves combined.
0:02:04 > 0:02:06The ant.
0:02:06 > 0:02:10You know, for every human on our planet,
0:02:10 > 0:02:13there are more than 14,000 of these.
0:02:14 > 0:02:19And, if we were to weigh all of the ants in the world,
0:02:19 > 0:02:21they would weigh as much as all of the people.
0:02:23 > 0:02:25And the key to their success?
0:02:25 > 0:02:26I'll tell you.
0:02:26 > 0:02:27Teamwork.
0:02:41 > 0:02:44In this episode, we'll explore the ingenious ways
0:02:44 > 0:02:49that ants have collaborated to overcome their greatest challenges.
0:02:53 > 0:02:55From starting a colony...
0:02:57 > 0:03:00..to housing and feeding that colony...
0:03:02 > 0:03:07..and finally, protecting it from some unexpected threats.
0:03:12 > 0:03:17At every step, it's all about the team.
0:03:36 > 0:03:38Dawn in the Arizona desert.
0:03:46 > 0:03:49A lone honey ant scratches around in the earth.
0:03:53 > 0:03:57It's taking the first steps of a remarkable journey.
0:03:59 > 0:04:03Every colony begins with a single ant,
0:04:03 > 0:04:06a lone queen like this one.
0:04:08 > 0:04:12Within months, it will number tens of thousands of residents.
0:04:17 > 0:04:20But to build the biggest and most powerful colony
0:04:20 > 0:04:23requires a number of queens working together.
0:04:39 > 0:04:43Within a few hours, these pioneers have burrowed deep underground.
0:04:45 > 0:04:47Descending into the darkness,
0:04:47 > 0:04:51this is the last time that any of them will see the light of day.
0:04:56 > 0:04:59They retire to their newly built chambers,
0:04:59 > 0:05:04where they'll lay thousands of eggs,
0:05:04 > 0:05:06each the size of a pinhead.
0:05:10 > 0:05:13Out of these emerge larvae that, within nine weeks,
0:05:13 > 0:05:16will grow into sterile female workers.
0:05:19 > 0:05:21They share a single mission -
0:05:21 > 0:05:25to serve the interest of the team.
0:05:28 > 0:05:32Each one destined for a specific role...
0:05:34 > 0:05:36..nurse maids to care for the young...
0:05:39 > 0:05:41..hunters to forage for prey...
0:05:46 > 0:05:48..and soldiers to protect them all.
0:05:55 > 0:05:59But first, they must make an extraordinary choice.
0:06:03 > 0:06:08Suddenly, the behaviour of the colony changes.
0:06:09 > 0:06:13The worker ants begin to bully and harass the queens...
0:06:16 > 0:06:19..searching for any sign of weakness...
0:06:24 > 0:06:28..testing each queen in turn to seek out the strongest...
0:06:34 > 0:06:36..before launching a bloody coup.
0:06:43 > 0:06:46The weaker queens are butchered...
0:06:58 > 0:07:02..their own offspring are among the executioners.
0:07:08 > 0:07:10But there is no room for sentiment.
0:07:11 > 0:07:15The strength of the regime is all that counts.
0:07:16 > 0:07:20The dead queens are chopped up and fed to the larvae.
0:07:35 > 0:07:39Now only the strongest and the most fertile queen remains.
0:07:45 > 0:07:47She is the absolute monarch.
0:07:58 > 0:08:02As the colony grows, and thousands of residents throng
0:08:02 > 0:08:06in the subterranean chambers, the ants face a new challenge.
0:08:12 > 0:08:16You see, most ant species nest underground,
0:08:16 > 0:08:21so ensuring a constant supply of oxygen is absolutely essential.
0:08:24 > 0:08:27Any failure to do so would almost certainly mean
0:08:27 > 0:08:31that the entire colony would slowly suffocate.
0:08:46 > 0:08:50In Argentina, one ant species has developed
0:08:50 > 0:08:53a particularly innovative solution.
0:09:06 > 0:09:11These leaf cutting ants have worked together to construct a home
0:09:11 > 0:09:13with an ingenious air conditioning system.
0:09:20 > 0:09:24The grand design exploits the cool surface wind...
0:09:27 > 0:09:30..redirecting this fresh air deep underground.
0:09:33 > 0:09:37The architecture and construction are highly sophisticated.
0:09:41 > 0:09:44The team builds two distinct sets of tunnels.
0:09:48 > 0:09:50As fresh air blows in...
0:09:54 > 0:09:57..carbon dioxide is pumped out.
0:10:05 > 0:10:10The system is further improved by vents on top of the tunnels,
0:10:10 > 0:10:14which help to maintain a constant temperature.
0:10:19 > 0:10:23It's the ideal solution for a permanent underground home.
0:10:30 > 0:10:34But, some colonies are constantly on the move
0:10:34 > 0:10:39and this requires a different kind of team-work.
0:11:01 > 0:11:05In East Africa, these driver ants have developed a nomadic lifestyle.
0:11:14 > 0:11:17When they move, they take the whole family with them.
0:11:25 > 0:11:28All the way from the precious eggs and larvae...
0:11:32 > 0:11:34..to the one and only queen.
0:11:39 > 0:11:42When it's time to set up home, they form temporary bivouacs.
0:11:46 > 0:11:51But the building materials are not the usual earth, sticks and rocks.
0:11:53 > 0:11:55These huge metre-wide structures
0:11:55 > 0:11:59are constructed from the ants themselves.
0:12:06 > 0:12:08With the precious queen safe inside,
0:12:08 > 0:12:11this is a royal palace with a difference.
0:12:14 > 0:12:18Complete with living columns, walls and ceilings.
0:12:22 > 0:12:26Luckily, every ant is more than capable of pulling their weight.
0:12:29 > 0:12:32Scientists have calculated that each individual
0:12:32 > 0:12:35can hold 5,000 times their own body weight.
0:12:44 > 0:12:48The bivouac is the physical embodiment of teamwork.
0:12:56 > 0:13:00With the colony complete, the next challenge is to feed the hordes.
0:13:03 > 0:13:08Now, in order to do this, the ants must first move as a team
0:13:08 > 0:13:12through some of the most challenging habitats on Earth.
0:13:12 > 0:13:15Once again, collaboration is key.
0:13:29 > 0:13:30The Amazon rainforest.
0:13:33 > 0:13:34Vast.
0:13:37 > 0:13:38Dense.
0:13:41 > 0:13:43And filled with hidden dangers.
0:13:53 > 0:13:57These army ants travel en masse wherever they go.
0:14:09 > 0:14:12And yet they are totally blind.
0:14:16 > 0:14:19Unable to rely on visual clues,
0:14:19 > 0:14:23the ants at the front secrete a chemical pheromone -
0:14:23 > 0:14:26a clear signal for their comrades to follow.
0:14:29 > 0:14:33Each successive ant then lays down more of the pheromone,
0:14:33 > 0:14:38eventually turning an unmarked jungle track
0:14:38 > 0:14:40into an ant super-highway.
0:14:53 > 0:14:56To decipher these chemical codes,
0:14:56 > 0:14:59ants draw on a highly developed sense of smell.
0:15:01 > 0:15:05They have over 400 distinct odour receptors,
0:15:05 > 0:15:09that's five times more than most other insect species.
0:15:19 > 0:15:22As the raiding party follows the scent trail,
0:15:22 > 0:15:26soldier ants take up their positions to guard the convoy's progress.
0:15:38 > 0:15:42Others selflessly lay down their bodies to bridge gaps
0:15:42 > 0:15:44and fill potholes...
0:15:49 > 0:15:52..allowing the whole team to continue unhindered.
0:15:54 > 0:15:58And with this army, no soldier is left behind.
0:16:00 > 0:16:04When the column has passed, the downtrodden ants climb up
0:16:04 > 0:16:05and join the rest of the team.
0:16:15 > 0:16:19The natural world's most efficient traffic system...
0:16:25 > 0:16:29..delivering thousands of ants quickly to the front line
0:16:29 > 0:16:31so they can hunt together effectively.
0:16:35 > 0:16:40In a single year, just one colony of these ants can capture,
0:16:40 > 0:16:45kill and consume ten million animals.
0:17:09 > 0:17:13This is an army that marches on its stomach
0:17:13 > 0:17:17and sheer numbers mean that nothing is off the menu.
0:17:20 > 0:17:24A heavily armoured freshwater crab wanders into the path
0:17:24 > 0:17:25of the hunting party.
0:17:37 > 0:17:40The team swarm over the tough outer defences,
0:17:40 > 0:17:43searching for any chinks in its armour.
0:17:51 > 0:17:55The large soldier ants target the vulnerable joints,
0:17:55 > 0:17:58ripping into the soft tissue.
0:18:04 > 0:18:09This allows the smaller workers to climb inside the legs
0:18:09 > 0:18:12and eat the crab from the inside out.
0:18:22 > 0:18:26Each member of ant society cooperating to achieve
0:18:26 > 0:18:31the seemingly impossible and supply the ravenous hordes.
0:18:36 > 0:18:40But when resources are scarce, what then?
0:19:00 > 0:19:02In the Arizona desert,
0:19:02 > 0:19:05some ants are sacrificed for the greater good of the team.
0:19:11 > 0:19:14These are repletes, honey ants that have been
0:19:14 > 0:19:19deliberately overfed in times of plenty by the rest of the colony...
0:19:20 > 0:19:24..until their abdomens look fit to burst.
0:19:30 > 0:19:32They're fixed to the ceiling,
0:19:32 > 0:19:35where the liquid is refined to produce a thick honey.
0:19:39 > 0:19:41Here they are held in reserve
0:19:41 > 0:19:44to feed their comrades when times are hard.
0:19:49 > 0:19:54They're living larders, just there to provide a sophisticated solution
0:19:54 > 0:19:57to the irregular supply of food in desert.
0:20:05 > 0:20:10When it comes to feeding the colony, ant ingenuity and teamwork
0:20:10 > 0:20:14has been taken to another level in Argentina.
0:20:19 > 0:20:24Although there appears to be plenty of food for these leaf-cutting ants...
0:20:27 > 0:20:30..the lush fields are actually deceptive...
0:20:32 > 0:20:36..because these leaves are naturally protected with cellulose,
0:20:36 > 0:20:40which ants are incapable of digesting.
0:20:41 > 0:20:45To combat this, the colony form a production line.
0:20:51 > 0:20:55Worker ants use their mandibles to cut up the leaves.
0:21:03 > 0:21:06Others then transport the harvest back to the colony...
0:21:18 > 0:21:23..where, underground, more ants chew the leaves to create a thick mash.
0:21:33 > 0:21:35This mash is then used as compost
0:21:35 > 0:21:41to cultivate a particular type of fungus that the ants can eat.
0:21:50 > 0:21:53They've been doing this for 50 million years,
0:21:53 > 0:21:58making them some of the oldest farmers on the planet.
0:22:06 > 0:22:09But ants don't stop at farming fungus.
0:22:18 > 0:22:24In Switzerland, these wood ants have a special interest in aphids.
0:22:26 > 0:22:30These tiny greenfly eat the sugary sap found in plants.
0:22:35 > 0:22:39They then process the sugars and excrete a sweet honeydew
0:22:39 > 0:22:43which the ants feed on directly from the aphids' rear ends.
0:22:52 > 0:22:55When they've had their fill, the ants return the favour.
0:23:01 > 0:23:06Acting as bodyguards, they protect the aphids from hungry predators.
0:23:12 > 0:23:17It's teamwork but it's teamwork at a whole new level.
0:23:30 > 0:23:34By working together, ants can build new colonies.
0:23:43 > 0:23:46Produce entire armies.
0:23:48 > 0:23:49Feed the masses.
0:23:52 > 0:23:57But this team ethic is also their Achilles heel.
0:24:05 > 0:24:08A tightknit colony can breed serious dangers.
0:24:13 > 0:24:17Thousands of individuals, living in such close proximity,
0:24:17 > 0:24:22make ant colonies particularly susceptible to the transmission of diseases.
0:24:23 > 0:24:27And because all of the ants in the colony are siblings,
0:24:27 > 0:24:30they are genetically very similar.
0:24:30 > 0:24:35A disease that kills one of them could easily kill them all.
0:24:39 > 0:24:43Paradoxically, teamwork is still the answer.
0:24:58 > 0:25:02These bullet ants have become infected by a parasitic fungus
0:25:02 > 0:25:05called cordyceps which is carried by the wind.
0:25:07 > 0:25:09It infiltrates the body...
0:25:10 > 0:25:14..and eventually explodes out of their brain.
0:25:19 > 0:25:22It then releases spores to infect other unsuspecting ants.
0:25:33 > 0:25:37A home that took years to build could be annihilated
0:25:37 > 0:25:38in no time at all.
0:25:40 > 0:25:42To counter this threat,
0:25:42 > 0:25:46infected ants are dumped far from the nest...
0:25:47 > 0:25:51..sacrificed for the health of the whole team.
0:26:05 > 0:26:07Back in Arizona,
0:26:07 > 0:26:10the honey ants must fight infection at every stage of their lives,
0:26:10 > 0:26:13from the cradle to the grave.
0:26:18 > 0:26:21Almost as soon as the queen lays her eggs,
0:26:21 > 0:26:24they're coated with antibiotic saliva
0:26:24 > 0:26:26that helps keep disease at bay.
0:26:37 > 0:26:41Even the larvae are continuously and rigorously cleaned.
0:26:51 > 0:26:54If an infected ant does enter the colony,
0:26:54 > 0:26:57the reception it receives is rather surprising.
0:27:04 > 0:27:09Far from being rejected, it's welcomed. And even cared for.
0:27:17 > 0:27:20The others share the infection around,
0:27:20 > 0:27:24each one accepting a tiny amount of the fungus.
0:27:33 > 0:27:37By actively applying a low level of infection to their healthy bodies,
0:27:37 > 0:27:39they build up immunity to the pathogen.
0:27:47 > 0:27:48This process of grooming
0:27:48 > 0:27:54works like the old method of human vaccination against smallpox,
0:27:54 > 0:27:57where low levels of exposure to disease,
0:27:57 > 0:28:00help the body generate immunity.
0:28:06 > 0:28:11Through sophisticated teamwork, ants have overcome every challenge.
0:28:13 > 0:28:17From the initial steps of building and housing a colony
0:28:17 > 0:28:20to moving as a group and feeding the entire team.
0:28:24 > 0:28:28And when threats come from within, well, then they band together
0:28:28 > 0:28:31to protect the colony from infections and disease.
0:28:33 > 0:28:38It's this extraordinary team ethic which has allowed ants
0:28:38 > 0:28:42to become one of the most numerous animals on planet Earth
0:28:42 > 0:28:46and THAT is the wonder of ants.