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15 Industrious Facts About Ants

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Ants may be small, but they’re a sophisticated species. They build intricate homes complete with sanitary facilities, take medicine to fight off infection, and teach each other things. Here are 15 surprising facts about the insects: 

1. THEY'RE NOT ALWAYS HARD WORKERS.

Despite ants’ reputation as dedicated workers, not every ant in the nest pulls her own weight. In one study of a nest of the North American species Temnothorax rugatulus, up to a quarter of the ants were inactive throughout the observation period. For reasons the scientists could not elucidate, these ants specialized in inactivity. 

2. THEY LOVE JUNK FOOD.

In 2014, a group of scientists left hot dogs, potato chips, and other junk food on the sidewalks of New York City to see how much human food ants were eating. After a day, they came back and weighed the food to see how much had disappeared. They found that along just one urban corridor, ants and other insects might be eating as much as 2100 pounds of junk food trash per year. 

3. SOMETIMES THEY RAISE BUTTERFLY LARVAE. 

The Alcon Blue butterfly sometimes fools Myrmica ants into raising its little ones. The ants occasionally mistake a faux-scent on caterpillar larva as evidence of its belonging to the nest, so they’ll pick it up and carry it home, providing food and protection for the foreign species as a kind of cuckold. 

4. THEY MAKE TOILETS FOR THEIR NESTS. 

Ants don’t just go anywhere. Some ants dump their waste just outside their nest, in a pile called a “kitchen midden.” Others, as scientists recently discovered, relieve themselves in specific spots within their nest. Even if they dispose of dead ants and other waste outside, black garden ants keep their frass (poop) in corners of their nests that are like little ant latrines. 

5. THEY TAKE MEDICINE WHEN THEY'RE SICK.

In a recent study, researchers found that when ants are exposed to a deadly fungus, they eat food laced with free radicals to fight off the infection. The free radicals damage the fungus cells, increasing the ants’ survival chances. 

6. THEY CAN TAKE DOWN PREY MANY TIMES THEIR SIZE.

The stinging Leptogenys ant mostly eats millipedes that can be several inches long. It takes dozens of ants to bring down a millipede, and the process is pretty intense to watch

7. THEY MIGHT FEEL SELF-DOUBT.

A 2015 study of black garden ants found that ants may be aware of when they don’t know something. When the ants in the study were put in an unpredictable situation, they were less likely to leave a pheromone trail that would encourage their fellow ants to follow them. This, the researchers argue, suggests that the insects know when they're not sure they're headed in the right direction. 

8. THEY CAN WALK ON WATER. 

The reason ants don’t drown in the rain? They’re so light that they don’t break the surface tension of water. They just walk on top of it

9. THEY HAVE SOME OF THE FASTEST REFLEXES IN THE ANIMAL WORLD.

Trap-jaw ants, carnivorous ants that live in South and Central America, can snap their jaws closed at speeds of up to 145 miles per hour

10. MALES DON'T HAVE FATHERS. 

Male ants come from unfertilized eggs and only have one set of chromosomes, which they receive from their mother. Female ants, on the other hand, are the result of egg fertilization and have two sets of chromosomes, one from their mother and one from their father. 

11. THEY COUNT THEIR STEPS. 

In windy desert environments, ants count their steps to find their way back to the nest after foraging. The 2006 study that proved this theory involved making ants’ strides shorter and longer in the lab through methods like cutting the tips of ants’ legs off and super-gluing others’ feet to stilts. 

12. THEY'VE BEEN TO SPACE. 

In 2014, a group of ants arrived on the International Space Station as part of a study to see how they would fare in microgravity. Despite the unusual environment, they were still able to work together to explore their territory. 

13. THEY'RE THE ONLY NON-HUMAN ANIMALS THAT TEACH. 

In a 2006 study, researchers found that Temnothorax albipennis ants lead each other to food, teaching other ants the path. They argued that it was the first observed instance of a non-human animal teaching another. 

14. THEY CAN ACT AS PESTICIDES.

A review of 70 studies on the use of weaver ants to protect crops finds the insects are effective at driving away pests from citrus and other tree crops. Weaver ants live in nests they build in trees and eat other insects. The study found that orchards with weaver ant nests had less plant damage and greater crop yields.

15. THEY CAN CLONE THEMSELVES. 

An Amazonian ant called Mycocepurus smithii reproduces through cloning. No male of the species has ever been found. Instead, the entire colony is made up of clones of the queen

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Adria C. LeBoeuf
Ants Communicate by Swapping Spit
Adria C. LeBoeuf
Adria C. LeBoeuf

Some insects’ mouth-to-mouth exchanges transmit tiny molecules of hormones and other important chemical information, according to scientists writing in the journal eLife.

The spit-swapping behavior is called trophallaxis. Many entomologists who witnessed the behavior in ants and other social insects believed the bugs were using it to efficiently share food. But some researchers noticed that carpenter ants were trophallax-ing in non-dining contexts, like when one ant would return to its family after being away. The scientists wondered if the ants’ kissing juice contained more than just calories.

They brought lots of ants into the lab to sample what the ants were sharing. At first, the researchers tried just waiting around until one ant initiated trophallaxis, but that mostly resulted in a lot of waiting and very little fluid. Eventually, they figured out that they could gently squeeze the ants’ bellies until the liquid came dribbling out of their mouths.

The researchers ran chemical and genetic tests on the fluid to determine its contents, and they found all kinds of interesting things. The liquid did indeed include particles of food and digestive enzymes, but it also contained several growth-related proteins and a juvenile hormone that can influence an insect’s development.

To find out how these compounds might affect a trophallaxis recipient, the researchers added the juvenile hormone to the meals they were feeding adult ants. The adults passed the hormone-charged liquid onto their larvae. The larvae loved it. Individuals who had taken in the hormone were twice as likely as others to survive to adulthood.

First author Adria LeBoeuf works at the Center for Integrative Genomics in Switzerland. She says the ants could very well be using trophallaxis to decide which larvae succeed. “When the ants feed their larvae, they aren’t just feeding them food, they are casting quantitative ballots for their colony, administering different amounts of growth-promoting components to influence the next generation,” she said in a statement.

Larvae chosen to receive the liquid are being nourished in more ways than one. In some ways, LeBoeuf says, it’s a lot like mammals’ milk. It also suggests that “…the oral exchange of fluids, such as saliva, in other animals might also serve previously unexpected roles." Yum.

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Josh Cassidy/KQED
Watch These Peruvian Tree-Protecting Ants in Ultra HD
Josh Cassidy/KQED
Josh Cassidy/KQED

In the Peruvian rainforest, a mutualistic relationship thrives between Inga tree saplings and native ants. The young trees need the ants as defense, so insects don't eat their leaves. The ants get "paid" for this defensive role using nectar provided by the tree.

In this beautiful Ultra-HD video from Deep Look, we see how this relationship works—and how it breaks down when clever Riodinid caterpillars come along!

The moral of this story? Never trust ants to protect you.

For more discussion, read this KQED article. Also fascinating is this paper by Suzanne Koptur (PDF link) describing the same ecosystem. There's also a nice It's Okay To Be Smart video on ant/tree mutualism.

And if you enjoyed this, watch another Deep Look video: What Do Ants Do With the Leaves They Carry Around?

(Photo courtesy of Josh Cassidy/KQED.)

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