The World War of the Ants – The Army Ant
Some groups just don't get along. Every day, billions of soldiers fight a merciless war on thousands of fronts, and it's been going on for over 100 million years. The World War of the Ants.
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Ants are ancient beings that arose around 160 million years ago and took over a wide variety of ecological niches so successfully that they became one of the dominant animals on planet Earth. Today, they count more than 16,000 different species with over 10,000 trillion individuals. Collectively, ants alone make up 20% of the entire animal biomass on land. Similar to humans, their recipe for success is collaboration.
While a single ant is pretty useless, together, they are able to achieve stunning feats. They construct complex colonies, care for livestock, pursue agriculture, or have complex symbiotic relationships. And of course, ants wage war. Even among the same species, a constant state of conflict is pretty common. Skirmishes, raids, and full-on invasions are happening every day, causing millions of casualties.
Let's look at some of the most interesting ones in a series of videos. In this one, the army ant, a swarm made for war. The army ant group consists of about 200 different species. Army ants do not build nests; they live a sort of nomadic lifestyle with groups of millions of individuals. On a hunt, some species form large columns up to 100 meters long, killing and immediately dismembering every insect or small vertebrate they encounter. The biggest hunting parties can kill up to 500,000 animals per day.
Some army ants specialize in hunting and consuming other social insects, like termites, wasps, and especially other ants. Wasps are fierce and may seem invulnerable, but if a swarm makes its way to their colonies, they don't even stand a chance. The much bigger and stronger wasps might kill a few of them, but they are quickly overwhelmed. Even if their queen survives an attack, the army ants steal the colony's larvae and quickly devour them. There is no recovery from that.
When army ants discover another ant colony, they immediately attack. Now you might think this would be a more even battle, but it's not. Because army ants act as a social unit, they are especially dangerous and effective. Most army ants are not particularly impressive individually, but they can overwhelm their victims with sheer numbers before the victim colony can mount an effective defense. And so invasions tend to be won by the attackers, and the prey colony is damaged significantly or is exterminated.
Interestingly, army ants don't fight army ants. When two swarms encounter each other in the wild, they either pass through each other, ignoring the other swarm, or both colonies just move away, which makes sense from an evolutionary standpoint. Army ants that fought other army ants probably eradicated themselves millions of years ago. Indeed they're so deadly that other ant species had to specialize to survive their presence.
Many species just panic and evacuate their nest when they notice army ant scouts, carrying as many larvae with them as they can, in order to return and rebuild after the attack. Other species have invented living bunkers since fighting is so futile. They have worker classes that have big square heads. When army ants show up, they use them to block the entrances to their nests, so the attackers have to give up after a while.
But not everybody is afraid of army ants. Leafcutter ants form some of the largest and most complex societies of any animal other than humans. They live in extensive nests, many meters deep and across, harboring millions of citizens with a highly sophisticated division of labor. Like huge soldiers, 100 times more massive than a worker. Their sole purpose might be to defend their colonies against army ants.
They still have a nemesis though. The diet of the army ant species Nomamyrmex esenbeckii consists mostly of the larvae of other ants. Compared to other army ants, they have a more robust soldier caste. So far, they are the only known species that can successfully attack a mature colony of leafcutters.
When they find a leafcutter colony, hundreds of thousands attack in a long column. The moment the leafcutter ants notice the army ant attack, they go into crisis mode and immediately alert their soldiers, who very quickly swarm to the site of attack. A frontline develops that can be a few meters wide and up to a meter deep.
The leafcutter soldiers go head-to-head with the army ants, locking on them and trying to cut through their heads. Smaller leafcutter workers help by grabbing the enemies. Small teams carry out attacks behind the frontline, where they dismember their enemies by ripping their legs from their bodies. The attackers meanwhile try to swarm their victim's soldiers and sting them to death in a mob.
Despite the powerful defense and the determined response, the army ants are still superior in numbers. So without knowing if the battle can be won, the leafcutters prepare for the worst. Workers rush to create barricades and seal off as many entrances to their nest as possible to secure their route.
If the leafcutters are not able to repel the invaders, or at least barricade enough of their entrances in time, the army ants swarm the nest, overrunning all opposition. They penetrate deep into the hidden chambers and steal tens of thousands of the leafcutters' brood to eat them. Even if the leafcutter colony survives, this is a heavy blow. Regardless of who's won the war, thousands lay slain on the battlefield.
When the army ants attack, death follows them. But there are other species that form much more dangerous ant armies. Species that form supercolonies covering thousands of square kilometers over multiple continents, engaging in wars kilometers across. They deserve their own video though.
No matter the scale, war is a part of ant existence. Be it between huge colonies, or small groups trying to fend off a raid. In tropical rainforests, but also in the cracks of the concrete we walk over every day. Humans have decided that war is not a thing that they want to do a lot anymore. For ants though, the other ant will always be the enemy.
No, some groups just don't get along.