Category
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AnimalsTranscript
00:00go on the attack.
00:30A tropical hill forest in East Africa, a place where animal communities co-exist, a
00:40natural balance between predators and prey.
00:47It's always been this way.
01:02But in this part of the forest, things are about to change.
01:12An extraordinary predator is moving in, one that will ravage this forest, probably the
01:22most formidable killer on earth.
01:27It's not an individual, but an entire army, an army of ants.
01:46This elite fighting force is a superorganism, 20 million sisters and a few males acting
01:53as one, the largest single family on the planet.
01:59The head of the family is a new queen, she'll produce the next generation and the army must
02:05keep her offspring alive.
02:06They must hunt successfully or the colony cannot grow.
02:14Our story is set in a parallel world to our own, a place where miniature monsters roam,
02:21and the most numerous and powerful survive.
02:24This is the bug-eats-bug world of the dreaded Siafu, the African driver ant.
02:50Driver ants don't have a permanent home, they're nomads.
02:58Every 23 days or so, they move from one part of the forest to another, and now they're
03:05here, somewhere, exploring new hunting grounds and searching for a temporary home, the neighbors
03:12from hell.
03:19But despite their huge numbers, you'd hardly notice they were here at all.
03:26They shun the light, operating down there, mainly amongst the dead leaves on the forest
03:32floor.
03:36They're swarm raiders, spreading through the forest, searching relentlessly for anything
03:41that moves.
03:45A super predator with a mother of all appetites.
03:54By hunting in such an enormous group, the ants can bring down creatures much larger
03:59than themselves.
04:06When one ant finds prey, she releases a chemical alarm signal, and within seconds, hundreds
04:12of ants join the attack.
04:17They vary considerably in size.
04:21The largest is a soldier, half an inch long, and like all the workers, she has no eyes.
04:27She's totally blind.
04:32She finds her way about using her two antennae, each covered in millions of hairs and sensory
04:37pits, alive to smells, vibrations, and touch.
04:45Her brain is minute.
04:47Instead, the large head is packed with muscles that move her gigantic, razor-sharp jaws.
05:00Her job is to protect the colony, for even driver ants have enemies.
05:08And when heavy-duty cutting is required, her powerful jaws can slice through a victim's
05:12skin like a knife through butter.
05:17Most of the attacking and butchering, though, is the job of the medium worker.
05:21She's about half the size of a soldier, also blind, and equipped with smaller, but tooth-studded
05:26jaws.
05:29Between them, soldiers and medium workers can bring down almost anything, including
05:34creatures as large and powerful as a grasshopper.
05:38They rely on overwhelming numbers and sheer persistence to capture their prey.
05:47They also provide most of the transport.
05:56Skittering about their feet is one of the smaller workers.
06:00Blind, like the others, and just an eighth of an inch long, she's a general helper who
06:05can do any job from butchering to building to cleaning.
06:10All three types cooperate to carry, push, or pull their prey along the supply lines
06:15from the swarm's raiding front to their next home.
06:23In day one in the new territory, the advance party has had some success.
06:27The ant army, like any army, marches on its stomach, and the first provisions are being
06:33stashed away, ready for the arrival of the rest of the colony.
06:46Eventually the first wave of workers is moving into the forest.
06:54They follow chemical trails that last for about a day, laid down by the ants ahead of
06:58them.
07:06Their new home is in a hollow at the base of a fallen tree.
07:12But the property is still only a building site.
07:18Construction workers enlarge the area, while groundworkers shift debris from the main chamber.
07:28These tiny creatures are strong.
07:33Each is carrying a load that in human terms would be more than enough for an Olympic weightlifter.
07:39Together they'll shift up to 80 pounds of soil in a couple of days.
07:51And they'll have to work fast, for the main colony is beginning to trickle in from the
07:55old nest site.
08:03When they enter the new chamber, some of the workers link together to form long garlands
08:07of ants that join floor to ceiling.
08:16They start to form a protective bivouac, shaped like a large round basket inside the nest
08:21hollow.
08:27And the whole structure will be made entirely of living ants.
08:35All they're waiting for now is...
08:40Between the old nest and the new, road gangs prepare the route along which the rest of
08:44the colony will trek.
08:52They excavate, build embankments, and dig tunnels, always trying to keep themselves
09:02hidden from view.
09:07They clear the highway of large pieces of soil that might slow down the traffic.
09:13And a hungry workforce must eat.
09:15Due to their enormous jaws, the larger ones can't feed themselves, so smaller ants spoon
09:21feed them.
09:30But first they must catch the food.
09:34The advance party has uncovered earthworms from under the leaf litter.
09:46The ants search for weak points between segments, their feelers constantly tasting and touching.
09:56When they've found the right spot, their jaws close with the equivalent force of a
10:05car crushing machine, and one worm becomes two.
10:15It's being divided into handy chunks, and then hauled back to camp.
10:26All the meat is fast-tracked to the kitchen orderlies deep in the nest.
10:30Here it's chopped, chewed, and distributed to the other ants.
10:34And while the advance party ensures the larder is full, the rest of the huge family prepares
10:40to leave the old nest site.
10:49It's day two, and the mass evacuation is underway.
10:57The ants march along well-worn tracks, originally the foraging trails between the old nest and
11:03the swarm front, but now the main roads along which queen and colony will pass.
11:11Their trek is about the length of two football pitches laid end-to-end, and they're not traveling
11:16empty-handed.
11:18Each ant carries a larva or a pupa hung below her body, the equivalent of us running a marathon
11:24while carrying a sack of potatoes and not stopping for a rest.
11:32The entire emigration can take up to three days.
11:41It seems chaotic, but every ant in this extraordinary melee knows exactly what she's doing.
11:55Giant soldiers with their massive jaws line the route, so the workers with their precious
11:59cargo can travel safely along a living avenue.
12:10They're passing at a rate of 250,000 ants an hour.
12:18Some unwittingly carry infiltrators.
12:21Even tiny ants are host to even tinier mites.
12:32The invading army is building in numbers.
12:52Traveling with her subjects is the queen.
12:56Two inches long, she's the largest ant in the world.
13:03And she's a new queen.
13:05When her mother's colony grew too large and divided, half the workers switched their allegiance
13:10and now accompany her on her first emigration.
13:24Her enormous bulk has been coaxed along the trail, and now she takes her place at the
13:29heart of the nest.
13:43The queen is in her palace, and what a palace it's become.
13:49It's a living bivouac, a nest made entirely of ants.
14:02All its internal walls are made of ants, all its corridors and chambers constructed of
14:07living bricks.
14:12And when they're all assembled in their new stronghold, they form one of the largest concentrations
14:18of ants on Earth.
14:25Protected by these living walls are the nurseries where wave after wave of brood carriers deliver
14:30their load.
14:37By the end of day three, they're packed with larvae and pupae.
14:52In the royal chamber, the queen has yet to restart her normal duties.
14:57Before her journey, she stopped egg production in order to slim down and make traveling easier.
15:04Now, like a virgin queen, she produces a special scent that attracts winged male ants who fly
15:12in from other nests.
15:16The male is also enormous, on a similar scale to the queen.
15:27The scents she produces are irresistible.
15:33Just a few molecules will grab a male's attention.
15:40He searches for a way into the nest, but a guard patrol has found him, and at first the
15:51other ants see him as food.
15:53He's actually in mortal danger.
16:01The army smothers him as if he were prey, but their intentions falter.
16:15He also produces scents to demonstrate his fitness to be consort.
16:19If he passes muster, he'll be accepted.
16:21If he doesn't, he'll be for the chop.
16:25They try to clip his wings so he'll fit through the nest entrance, but he cooperates, using
16:31spikes at the end of his abdomen, he pulls one off himself.
16:41Nothing is wasted, even a wing has some nutritional value.
16:48The rest of the workers take him into the nest.
16:51He has their support, at least for the time being.
16:55He's on probation.
16:58Until he actually mates with the queen, he could still be attacked.
17:04Another wing is removed.
17:10He'll soon be presentable for his audience with the queen.
17:19It's day five in the new territory.
17:22There's no nuptial flight.
17:24Instead, the queen's new consort is guided directly to the royal chamber.
17:29He's not the first consort to the queen, and he probably won't be the last.
17:34Driver ant queens are, for ants, unusually promiscuous.
17:38He'll be one of many suitors she'll entertain during her lifetime.
17:44His job done, he retires from the royal chamber and dies.
17:49A short but productive life, for he'll father several million new ants with hungry mouths.
17:56The pressure is building for the colony to provide more and more food.
18:03The raiders head west, and they don't stay on the ground.
18:10There's plenty to eat up here in the trees.
18:14A male hornbill cements his family into a hole in the trunk,
18:19leaving a small gap through which he passes food.
18:22It'll keep out tree snakes, but not ants.
18:29Driver ants would strip the flesh from the female hornbill and her chicks in a matter of hours.
18:35He's understandably nervous.
18:41The ants are as adept at climbing as they are at running.
19:00As long as the forest is dark and humid, they seem as at home in the trees as they are on the ground.
19:11The army is close.
19:20But not close enough.
19:23If the ants climb too high and are too spread out, they'll be too few to overwhelm prey.
19:32This nest is out of reach.
19:35The family is safe.
19:43But there's plenty more prey up here.
19:46Slugs are fair game for driver ants.
19:49They don't run away.
19:53The first ant makes contact.
20:03And then another.
20:05Others come running.
20:08The slug tries to sit out the attack.
20:12There are so many ants.
20:18The victim uses the only escape route left to it.
20:25The ants fall, too.
20:27They often use this unconventional way to get down from the trees.
20:32But the unfortunate slug has fallen from the frying pan into the fire.
20:40An awful lot of ants are milling about down here.
20:47They smother their prey.
20:51But the slug has a trick up its sleeve.
20:56It may be slow, but it's well-protected.
21:01Its entire body is covered in a thick and noxious slime.
21:05It's so glutinous that once their jaws are in, they can't get them out.
21:16The slug is a bit of a pain in the ass.
21:20The slug is a bit of a pain in the ass.
21:24It's so glutinous that once their jaws are in, they can't get them out.
21:31Other ants seem to give a helping hand.
21:55But this one is firmly stuck.
22:03Try as she might, she just can't get away.
22:09For some, it's not just their jaws that are trapped.
22:40She's almost free.
22:51Then something remarkable happens.
22:55Some of the workers begin to bring particles of soil and place them on the slug.
23:01In this way, the slime is soaked up, like ink on blotting paper.
23:08Gradually, the slug disappears under a writhing mass of earth and ants.
23:25With its protective coat neutralized, the ants attack the slug underneath.
23:31Slowly, the victim is sliced up.
23:47Piece by piece, small chunks are pulled away.
24:02As the flesh is removed, the butchers switch roles and become transporters.
24:08They carry the food along the foraging trails back to camp.
24:14The larvae will be fed tonight.
24:18By day ten, the queen resumes her primary role as supermother, the ultimate egg-laying machine.
24:25Food is served to her at one end, and eggs appear at the other.
24:33She produces a staggering two million eggs a month.
24:41The palace staff bustles around her, collecting packages of eggs, grooming her constantly.
24:47She's the colony's most valuable asset, a link to the future.
24:55The ants around her are quite prepared to die for her,
25:01not because of any love for a mother, but simply because they're protecting the blueprint
25:07that makes them what they are and what they do.
25:13They pick up clumps of the precious eggs and gently carry them away to the nursery.
25:19The already huge ant population is increasing exponentially,
25:25and the demand for food is growing astronomically.
25:31There's a need for a greater-than-ever increase in rations.
25:37Having raided to the north and west and eliminated every living thing that slithers or crawls,
25:43the columns head south.
25:49The raid takes them into a wet and swampy area.
25:55This is no deterrent. Driver ants are proficient at crossing difficult terrain.
26:02But a river is something even they can't manage.
26:08They've reached the southern edge of their territory, and water and ants don't mix.
26:15They head back inland, and straight into another battle.
26:21This time, it's a battle for the lifeblood of the colony.
26:28They head back inland, and straight into another barrier.
26:34But a shallow pond is no obstacle.
26:40In order to cross, the ants simply build a bridge.
26:46The ants can't cross the bridge,
26:52but in order to cross, the ants simply build a bridge.
27:11It's made out of leaves, and the ants themselves. A living bridge.
27:22The swarm raiders stream across the pond,
27:28but the raid is failing.
27:34They're carrying little food.
27:40The ants retreat.
27:47But fortunes change.
27:53The raiding party has flushed out what seems an unassailable quarry.
28:01Freshwater crabs are common in the forest,
28:07but a surprising target for ants.
28:14At first, the raiders do what's natural.
28:17They swarm all over their intended victim,
28:20but there's no way their tiny jaws are going to pierce the crab's thick outer skeleton.
28:26Instinctively, they probe for its weak points.
28:30One group examines the legs and claws for a way in.
28:34This has its dangers.
28:37They search for the vulnerable joints and hack their way into the leg.
28:42Using knife-like mandibles, they slice away the soft tissue,
28:47and as the joint is ripped and the tear widened,
28:50the smaller workers are able to climb right into the crab's legs to reach the muscles inside.
29:13Another group checks out the mouth.
29:23They seem to work together.
29:25The larger soldiers prise open the mouthparts,
29:28so smaller workers can squeeze through and attack the softer tissues behind.
29:35The ants are dwarfed by the crab,
29:38but with so many attacking at one time, even a fully armored crab doesn't stand a chance.
29:45Ants eat from inside out.
29:52By day 22, raiding parties have quartered almost every part of their territory,
29:58and down in the brood chambers, there are now four million more mouths to feed.
30:03The larvae are voracious, and the raiders barely keep pace with their demand for food.
30:25The family is at crisis point.
30:34There's just one part of the forest left to explore,
30:38and here they stumble upon an unexpected prize,
30:42a mound made by forest termites.
30:49Termites have a permanent home, more a fortress than a nest.
30:53Inside live two million residents.
30:56Now winged termites are leaving the safety of the nest,
31:00now winged termites are leaving the safety of the mound.
31:06They're the future kings and queens, and they do go on a nuptial flight.
31:11Late in the day, they emerge from the nest.
31:20Just a few fail to fly very far.
31:25They'll be easy pickings.
31:31The reign of this yacht, as will its life.
31:37The ants swarm over any termite that falls short.
31:49The work detail tries to control and snip off the unmanageable wings.
31:55For a tiny ant, it's like wrestling with a gigantic sail.
32:03Others anchor down their victim by holding onto its legs.
32:16As the hauliers keep pulling and pushing, the butchers keep slicing.
32:25The raiding party heads home with an almost headless victim,
32:29but their haul of a few ditched termites is far less than the colony needs.
32:40As the evening draws in and the temperature drops,
32:44the ants become lethargic.
32:47They head back to their nest for the night,
32:50but in returning home, they miss out on the biggest feast
32:53there's been in this part of the forest for a long time.
33:03The main exodus of winged termites is this night.
33:07Tens of thousands emerge at the same time.
33:14This would be such a glut of ant food,
33:17it would satisfy the 20 million of them for several days.
33:21But the ants are not here.
33:23The termites are on the wing, the feast is flying away,
33:27and the ant brood is demanding increasingly more food.
33:31If none is forthcoming, the new generation could be put on hold.
33:35The next 24 hours are critical.
33:48A new day, and for the ants, a renewed challenge.
34:00This has been their home for 23 days.
34:03Successful hunting means their forest larder is almost bare.
34:09The entire army is mobilising.
34:13The raiding parties head out to the last place they'd found food,
34:17where they had pinned down the few winged termites.
34:22The bearing they've taken with them is now in the hands of the hunters.
34:26This way, they'll be able to carry on their hunt.
34:32An ant-free food is an ant-free meal,
34:35but it's not always the same.
34:38The ant-free meal is the meal of the day.
34:41It's the meal of the day.
34:44It's the meal of the day.
34:47It's the meal of the day.
34:50The bearing they've taken is leading them straight towards the termite mound itself.
35:02Ants and termites have been adversaries for over a hundred million years.
35:07Now their armies of today are on a collision course.
35:11But without any physical contact, the blind army is as unaware of the termites ahead
35:17as the termites are of the approaching ants.
35:21They begin to swarm over the outside of the termite towers
35:25that for the moment appear to them to be just mounds of dried mud.
35:29.
35:46Guards are posted while others explore every crevice for any sign of food.
35:54First contact. The ants know there's something here
35:57and change direction towards the alarm signal.
36:00They mass around, the guards alert for any unpleasant surprises.
36:09This is unknown territory. Anything could be lying in wait down there.
36:17A worker gingerly explores the gaping hole
36:20and a scouting party lays a scent trail for others to follow.
36:28Activity increases. An assault is on.
36:41Other ants have found the termites foraging tunnels and scramble inside.
36:46The tunnels are narrow and not at all like the open spaces driver ants prefer.
36:52Termite soldiers with enormous jaws and heads prepare to check the incursion.
37:03A soldier termite confronts the invaders with a threat display,
37:07but it's not going to impress a driver ant.
37:15The ants penetrate deeply into the ground.
37:19The ants penetrate deep into the nest and the residents intensify their warning.
37:31First blood is to the termites.
37:37But the tunnel guards are in danger of being overrun.
37:48The ants break through the first line of defense.
38:08Another wave of ants advances unchallenged.
38:11But the attack is not going to plan.
38:16In the tunnels, the ants become embroiled in one-to-one duels.
39:11The jaw-to-jaw combat is at stalemate.
39:14Ants and termites seem locked in a lethal embrace.
39:26The adversaries are well matched.
39:41The ants are pulling out.
39:48Their army will have to look elsewhere.
39:55But not all are going home.
40:08Those who can move out do so.
40:11The termite mound has defeated them.
40:14They must find food in another part of the forest.
40:33For the ant army, a big change is inevitable.
40:41The queen makes ready for a journey.
40:49The lower ranks gather up all the larvae in the nursery and move them to the nest entrance.
41:04They've depleted the food supply in the vicinity of their nest and must leave.
41:11They've outstayed their welcome.
41:25Swarm raiding parties have located a concentration of food 200 yards further on.
41:30So the entire colony must relocate in order to exploit it.
41:35They've wreaked havoc here, so they're moving on to terrorize another part of the forest.
41:42Yet the ants are important to the forest's well-being.
41:47The wholesale culling of bugs and slugs ensures that no one species dominates.
41:54Driver ants help maintain the huge range of plants and animals.
41:58Despite all the killing, driver ants are an essential part of the colony.
42:04An essential part of forest life.
42:06In many ways, the good guys after all.
42:18Quality drama in high definition next here on BBC HD.
42:2120,000 Streets Under the Sky continues in a moment.
42:25And then tomorrow, another chance to see episode two of our brand new series
42:29following the adventures of Robin Hood at 7.45.