Natural World (1983) s24e13 Episode Script

A tropical hill forest in east Africa a place where animal communities coexist a natural balance between predators and prey It's always been this way But in this part of the forest, things are about to change An extraordinary predator is moving in One that will ravage this forest probably the most formidable killer on earth It's not an individual but an entire army an army of ants This elite fighting force is a super organism 20 million sisters and a few males acting as one the largest single family on the planet The head of the family is a new queen She'll produce the next generation and the army must keep her offspring alive They must hunt successfully or the colony cannot grow Our story is set in a parallel world to our own a place where miniture monsters roam, vilence is the law and the most numerous and powerful survive This is the bug-eats-bug world of the dreaded Siafu, the African driver ants Driver ants don't have a permanent home they are nomads Every 23 days or so, they move from one part of the forest to another and now they are here, somewhere exploring new hunting grounds and searching for a temporary home the neighbors from hell Yet despite their huge numbers, you'd hardly notice they were here at all They shun the light, operating down there mainly amongst the dead leaves on the forest floor They're swarm raiders, spreading through the forest searching relentlessly for anything that moves A super predator with a mother of all apetites By hunting in such enormous group, the ants can bring down creatures much larger than themselves When one ant finds prey, she releases a chemical alarm signal and within seconds hundreds of ants join the attack They vary considerably in size The largest is a soldier, half an inch long and like all the workers she has no eyes She's totally blind alive to smells, viberations and touch Her brain is minute Instead, her large head is packed with muscles that move her gigantic razor-sharp jaws Her job is to protect the colony for even driver ants have enemies And when heavy duty cutting is required her powerful jaws can slice through a victim's skin like a knife through butter Most of the attacking and butchering though is the job of the medium worker She's about half the size of a soldier, also blind and equipped with smaller but tooth-studded jaws Between them, soldiers and medium workers can bring down almost anything including creatures as large and powerful as a grasshopper They rely on overwhelming numbers and sheer persistence to capture their prey They also provide most of the transport Skittering above their feet is one of the smaller workers Blind like the others and just an 8th of an inch long she's a general helper who can do any job from butchering to building, to cleaning All 3 types cooperate to carry, push or pull their prey along the supply lines from the swarm's raiding front to their next home During day one in the new territory the advance party has had some success The ant army like any army marches on its stomach And the first provisions have been stashed away ready for the arrival of the rest of the colony Already the first wave of workers is moving into the forest They follow chemical trails that last for about a day laid down by the ants ahead of them Their new home is in a hollow at the base of a fallen tree But the property is still only a building site Construction workers enlarge the area while ground workers shift debris from the main chamber These tiny creatures are strong Each is carrying a load that in human terms would be more than enough for an Olympic weight-lifter Together, they'll shift up to 80 pounds of soil in a couple of days And they'll have to work fast for the main colony is beginning to trickle in from the old nest site When they enter the new chamber, some of the workers link together to form long garlands of ants that join floor to ceiling They start to form a protective bivouac shaped like a large round basket inside the nest hollow And the whole structure will be made entirely of living ants All they're waiting for now is enough workers to fill the gaps Between the old nest and the new, road gangs prepare the route along which the rest of the colony will trek They excavate build embankments and dig tunnels, always trying to keep themselves hidden from view They clear the highway of large pieces of soil that might slow down the traffic And a hungry workforce must eat due to their enormous jaws the larger ones can't feed themselves so smaller ants spoon-feed them But first they must catch the food The advance party has uncovered earthworms from under the leaf litter The ants search for weak points between segaments Their feelers constantly tasting and touching When they've found the right spot, their jaws close with the equivalent force of a car crushing machine and one worm becomes two It's been divided into handy chunks and then hauled back to camp All the meat is fast track to the kitchen orderlies deep in the nest Here, it's choped, chewed and distributed to the other ants And while the advance party ensures the larder is full the rest of the huge family prepares to leave the old nest site It's day two and the massive excuation is underway The ants march along well-worn tracks originally the foraging trails between the old nest and the swarm front but now the main roads along which queen and colony will pass Their track is about the length of two football pitches laid end to end And they're not travelling empty-handed Each ant carries a lava or a pupa hung below her body The equivalent of us running a marathon while carrying a sack of potatoes and not stopping for a rest The entire emigration can take up to 3 days It seems chaotic but every ant in this extraordinary melee knows exactly what she's doing Giant soldiers with their massive jaws line the route so the workers with their precious cargo can travel safely along a living avenue They're passing at a rate of 250,000 ants an hour Some unwittingly carry infiltrators Even tiny ants are host to even tinier mites The invading army is building in numbers Traveling with her subjects is the queen At 2 inches long, she is the largest ant in the world And she is a new queen When her mother's colony grew too large and divided half the workers switched their allegiance and now accompany her on her first emigration Her enormous bulk has been coaxed along the trail and now she takes her place at the heart of the nest The queen is in her palace and what a palace it's become It's a living bivouac a nest made entirely of ants All its internal walls are made of ants all its corridors and chambers constructed of living bricks And when they are all assembled in their new stronghold, they form one of the largest concentrations of ants on earth Protected by these living walls are the nurseries where wave after wave of brood carriers deliver their load By the end of day three, they're packed with larvae and pupae In the royal chamber, the queen has yet to restart her normal duties Before her journey, she stopped egg production in order to slim dow and make traveling easier Now, like a virgin queen she produces a special scent that attracts winged male ants who fly in from other nests The male is also enormous, on a similar scale to the queen The scents she produces are irrestable Just a few molecules will grab a male's attention He searches for a way into the nest But a guard patrol has found him and at first the other ants see him as food He's actually in mortal danger The army smothers him as if he were prey but their attentions falter He also produces scents to demonstrate his fitness to be consort If he passes muster, he'll be accepted and if he doesn't, he'll be for the chop They try to clip his wings, so he'll fit through the nest entrance but he cooperates using spikes at the end of his abdomen, he pulls one off himself Nothing is wasted even a wing has some nutritional value The rest of the workers take him into the nest he has their support, at least for the time being he's on probation Until he actually mates with the queen, he could still be attacked Another wing is removed He'll soon be presentable for his audiance with the queen It's day 5 in the new territory There's no nuptial flight instead the queen's new consort is guided directly to the royal chamber He's not the first consort to the queen and he probably won't be the last Driver ant queens are, for ants, unusually promiscuous he'll be one of many suitors she'll entertain during her lifetime His job done, he retires from the royal chamber and dies a short but productive life for he'll father several million new ants with hungry mouths The precious building for the colony to provide more and more food The raiders head west and they don't stay on the ground There's plenty to eat up here in the trees A male hornbill cements his family into a hole in a trunk leaving a small gap through which he passes food It will keep out tree snakes but not ants Driver ants would strip the flesh from the female hornbill and her chicks in a matter of hours He's understandably nervous The ants are as adept at climbing as they're at running As long as the forest is dark and humid they seem as at home in the trees as they are on the ground The army is close but not close enough If the ants climb too high and are too spread out they'll be too few to overwhelm prey This nest is out of reach her family is safe But there's plenty more prey up here Slugs are fair game for dirver ants they don't run away The first ant makes contact And then another others come running The slug tries to sit out the attack There're so many ants The victim uses the only escape route left to it The ants fall too they often use this unconventional way to get down from the trees But the unforturnate slug has fallen from the frying pan into the fire And aweful lot of ants are milling about down here They smother their prey But the slug has a trick up its sleeve It may be slow, but it's well-protected Its entire body is covered in a thick and noxious slime It's so glutinous that's once their jaws are in, they can't get them out Other ants seem to give a helping hand But this one is firmly stuck Try as she might, she just can't get away For some, it's not just their jaws that are trapped She's almost free then something remarkable happens Some of the workers begin to bring particles of soil and place them on the slug In this way, the slime is soaked up like ink on blotting paper Gradually the slug disappears under a riving mass of earth and ants With its protective coat neutralised, the ants attack the slug underneath Slowly the victim is sliced up Piece by piece, small chunks are pulled away As the flesh is removed, the butchers switch roles and become transporters They carry the food along the foraging trails back to camp the larvae will be fed tonight By day 10, the queen resumes her primary role as super mother the ultimate egg-laying machine Food is served to her at one end and eggs appear at the other She produces a staggering 2 million eggs a month A palace of staff bustles around her collecting packages of eggs grooming her constantly She's the colony's most valueable asset a link to the future The ants around her are quite prepared to die for her not because of any love for a mother but simply because they're protecting the blueprints that makes them what they are and what they do They pick up clumps of the precious eggs and gently carry them away to the nursery The already huge ant population is increasing exponentially and the demand for food is growing astronomically There's a need for a greater than ever increasing rations Having raided to the north and west and eliminated every living thing that slithers or crawls the column heads south The raid takes them into a wet and swampy area This is no deterrent diver ants are proficient at crossing difficult terrain But a river is something even they can't manage They've reached the southern edge of their territory and water and ants don't mix They head back inland and straight into another barrier But a shallow pond is no obstacle In order to cross, the ants simply build a bridge It's made out of leaves and the ants themselves a living bridge The swarm raiders stream across the pond but the raid is failing They're carrying little food the ants retreat But fortunes change the raiding party has flushed out what seems an unassailable quarry Freshwater crabs are common in the forest, but a surprising target for ants At first, the raiders do what's natural They swarm or over their intended victim but there's no way their tiny jaws are going to pierce the crab's thick outer skeleton Instinctively, they probe for its weak points One group examines the legs and claws for a way in It has its dangers They search for the vulnerable joints and hack their way into the leg using knife-like mandibles, they slice away the soft tissue and as the joint is ripped and the tear widened the smaller workers are able to climb right into the crab's legs to reach the muscles inside Another group checks out the mouth They seem to work together The larger soldiers prise open the mouth parts, so smaller workers can squeeze through and attack the soft tissues behind The ants are dwarfed by the crab Yet with so may attacking at one time, even a fully armoured crab doesn't stand a chance Ants eat from inside out By day 22, raiding parties have quartered almost every part of their territory and down in the brood chambers, there are now 4 million more mouths to feed The larvae are voracious and the raiders barely keep pece with their demand for food The family is at a crisis point There's just one part of the forest left to explore And here they stumble upon an unexpected prize A mound made by forest termites Termites have a permanent home more a fortress than a nest Inside live 2 million residents now wing termites are leaving the safety of the mound They're the future kings and queens and they do go on a nuptial flight Late in the day, they emerge from the nest Just a few fail to fly very far they'll be easy pickings The reign is very short, as with its life The ants swarm over any termite that fall short The work detail tries to control and snip off the unmanageable wings For a tiny ant, it's like wrestling with a gigantic sail Others anchor down their victim by holding on to its legs As the hauliers keep pulling and pushing, the buchters keep slicing The raiding party heads home with an almost headless victim But their haul of a few ditch termites is far less than the colony needs As the evening draws in and the temperature drops the ants become lethargic They head back to their nest for the night but in returning home, they miss out on the biggest feast there's been in this part of the forest for a long time The main exodus of wing termites is this night tens of thousands emerge at the same time This would be such a glut of ant food, it would satisfy the 20 million of them for several days But the ants are not here The termites are on the wing, the feast is flying away and the ant brood is demanding increasingly more food If none is forthcoming, the new generagtion could be put on hold The next 24 hours are critical A new day and for the ants a renewed challenge This has been their home for 23 days successful hunting means their forest larder is almost bare The entire army is mobilizing The raiding parties head out to the last place they'd found food where they had pinned down the few wing termites The bearing they've taken is leading them straight towards the termite mound itself Ants and termites have been adversaries for over 100 million years Now their armies of today are on a collision course but without any physical contact, the blind army is as unaware of the termites ahead as the termites are of the approaching ants They begin to swarm over the outside of the termite towers that for the moment, appear to them to be just mounds of dried mud Guards are posted while others explore every crevice for any sign of food First contact, the ants know there's something here and change direction towards the alarm signal They mass around, the guards alert for any unpleasant surprises This is unknown territory anything could be Iying in wait down there A worker gingerly explores the gapping hole and a scouting party lays a scent trail for others to follow Activity increases, an assault is on Other ants have found the termites' foraging tunnels and scramble inside The tunnels are narrow and not at all like the open spaces driver ants prefer Termite soldiers with enormous jaws and heads prepare to check the incursion A soldier termite confronts the invadors with a threat display but it's not going to impress a driver ant The ants penetrate deep into the nest and the residents intensify their warning First blood is to the termites but the tunnel guards are in danger of being overrun The ants break through the first line of defence Another wave of ants advances unchallenged but the attack is not going to plan In the tunnels, the ants become embroiled in one to one duels The jaw to jaw combat is at a stalemate ants and termites seem locked in a lethal embrace The adversaries are well-matched The ants are pulling out Their army will have to look elsewhere But not all are going home Those who can move out do so the termite mound has defeated them They must find food in another part of the forest For the ant army, a big change is inevitable The queen makes ready for a journey The lower ranks gather up all the larvae in the nursery and move them to the nest entrance They've depleted the food supply in the vicinity of their nest and must leave They've outstayed their welcome Swarm raiding parties have located a concentration of food 200 yards further on so the entire colony must relocate in order to exploit it They've wreaked havoc here so they're moving on to terrorise another part of the forest Yet the ants are important to the forest's well-being The wholesale culling of bugs and slugs ensures that no one species dominates Driver ants help maintain the huge range of plants and animals Despite all the killing, driver ants are an essential part of forest life In many ways, the good guys after all