18May2019

Andaman Chronicle

The Daily Diary of the Islands

Somewhat Like Humans

By Maneka Sanjay Gandhi

We are just so lucky that the 13,000 species of ants, discovered till now, are small. Even if they were the size of cats, they would be the rulers of the universe by now, would have discovered ways to reach Mars, and colonise the moon, would have solved any mathematical or gravitational problems, would have built weapons without metal. They would have sailed the oceans and destroyed as many other species as possible. They would be in constant warfare, but their wars would not destroy the land around them, or foul the air and water.

I simply love ants. I find them exactly like human beings, little mini-mes. with all our awful instincts and yet deadly precision and efficiency with no waste.

I could go on forever about them, because I learn more every day. We have everything in common. They fight all the time as well. Like people, ants have often fought over food and territory. But ants began fighting with each other, or other nests of their own species, or other species, long before humans: at least 99 million years ago when dinosaurs ruled the earth, according to a fossil insect experts in the Department of Biological Sciences at Rutgers University-Newark published online in the journal Current Biology. Ants have been trapped in ancient Burmese amber while fighting to the death. These “hell ants” had mammoth like tusk-jaws which were used to impale prey - which, fortunately, modern ants don’t have. In Mark Moffett's Book, Adventures Among Ants, he writes about the territorial disputes between two huge colonies of Argentine ants in California. Along the front line literally millions of ants die every month in what is a never-ending struggle. Sounds like India and Pakistan. Even Charles Darwin wrote about human like conflicts between ants.

Here are some similarities:

* The Florida ant (Formica archboldi) decorates its nest with the skulls of its enemies, the trap jaw ants. But trap jaw ants are bigger, have stingers and mouths that close like bear-traps and have a special feature - they can catapult to freedom when attacked. How does the much smaller archboldi do it ?

A study published in the journal Insectes Sociaux reveals that F. archboldi possesses acid spraying nozzles (like machine guns)  and attacks its quarry with quick sprays of toxic acid. They cut off the heads of their victims and take them back as trophies. But first they hide themselves within the trapdoor ants by producing a waxy layer of scent that matches the smell of the trap door ant perfectly! Chemical cues are vital to ants. While ants have eyes, they rely on scents to  follow their nest mates to food, identify friend from foe.

* However, archboldi ants have their own problems. Polyergus ants kidnap and brainwash entire colonies of F. archboldi. In fact, they are known as pirate /kidnapper ants and their modus operandi is as follows : The kidnapper ant queen identifies an archboldi ant colony. She sneaks in, murders the queen, and then bathes in her blood. She takes her place, using this newly acquired scent to avoid detection and pumps out a bunch of eggs inside the archboldi nest. These hatch into polyergus workers who capture the rest of the nest.

* Researchers have documented the first known instance of insects moving prey by forming chains. Bluish Leptogenys ants drag huge millipedes in Phnom Kulen National Park, Cambodia. Each ant bites on a constriction on the abdomen of the ant ahead of it, while the first ant bites tight on the millipede's antenna. Walking backwards, the ants heave the millipede away. Other ants form chains too. Weaver ants and army ants build chains to sew nests and cross waters respectively. But the Leptogenys ants are the first insects known to move prey by making long chains. Some ants walk ahead of the chains clearing the path.

* The big-headed ant (Pheidole megacephala) colonies have soldier ants with disproportionately large heads and giant jaws which they use to attack other ants and cut up prey. According to the Biological Journal of the Linnean Society, big-headed ant soldiers grow larger when they encounter other ants that know how to fight back.

Big-headed ants are world travellers, hitching rides with humans to get around. Their arrival at a warm destination spells almost certain doom for native ants, spiders, beetles and other invertebrates.

Big-headed ants spread out, assembling multiple nests that cooperate on defence, reproduction, territorial expansion and food procurement. If their prey are not aggressive the ants remain the same size. But if they encounter competitors in the local area they can grow to three times their size. Genetic analysis shows that the size variation is not the result of long-term evolutionary change. It is simply a uniquely quick response (within 60 days) to a new environment.

* Trap jaw ants train to fight by holding antenna boxing bouts. These bouts also establish levels of dominance within the nest. Ants have a hierarchy of roles within the colony. Trap-jaw ant species engage in antennal "boxing," a quick fight involving striking one another with their antennae, to determine which of the worker ants stay in the nest and which go out to forage. Entomologists at the University of Illinois, whose findings are in the journal Insectes Sociaux,  counted how rapidly four species pummelled their opponents during antenna-boxing bouts. The speeds ranged from 19.5 strikes per second for Odontomachus rixosus, from Cambodia, to a blazing-fast 41.5 strikes per second for Odontomachus brunneus, of Florida. Trap-jaw ants are the fastest boxers ever recorded.

* Terrorists and Colbopsis Explodens ants from Borneo have the same suicidal strategies, according to the study published in the journal ZooKeys. When confronted by another insect, the ants actively burst their body walls and release a sticky, toxic substance that can repulse or even kill the enemy. The workers die in the attack as well.

* Army ants send out a huge raiding party that sweeps through the forest. If they find the swarm raid of another army ant nest they either ignore each other: the two huge swarm parties pass through each other almost as if the other did not exist. Or both colonies retreat in opposite directions, away from each other. But if they find another species of ants, like Leafcutter ants, they attack, even if it is very large colony. Soldiers of both species line up and engage in absolutely cataclysmic battles that go on for days before the army ants finally break through the defence and go down to the leaf-cutter nest and pillage the brood.

When army ants arrive the prey ant colony evacuates the nest. What they usually do is, they grab the babies and run out to a distance. There they stand and wait. After the army ants depart, the prey ants go back to the nest.

* Wars need backups in the form of medics to save the wounded. Megaponera analis, a small black ant species native to sub-Saharan Africa, wages war on termite nests. Attacking ants can have limbs ripped off by termites. Instead of leaving the hurt ants behind, other ants will carry them back home where they can heal and participate again in future raids. Once back at the nest, healthy ants attend to the wounded, licking their injuries for minutes at a time. This strikingly unusual behaviour raises the survival rate for injured ants from a mere 20 percent to 90 percent, according to research published in the journal Proceedings of the Royal Society. M. analis colonies aren't that large, and only a dozen or so baby ants are born each day. Losing one or two ants each day would be quite significant, so they find ways to reduce the mortality.

* In the United States, the South American fire ant armies are being beaten back by the armies of a new invader – the tawny Crazy Ant. In the journal Science, entomologists at the University of Texas explain why the smaller tawny crazy ants are winning.

Fire ants spew extremely toxic venom at other ants. Most ants just die. But the Crazy ants charge into the fray. The key to their success is their chemical defences. Once an ant is sprayed, it retreats from the battle and applies its own caustic venom, which acts like a healing salve, neutralizing the effect of the fire ant's toxic ammunition. And then they run back into the fight. This tactic is so effective that the fire ant populations are dying out.

Ants tend to separate the world in a rather simple way, into two classes: colony members and everybody else. Somewhat like humans.

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