Name: The Insane Biology of: Ant Colonies
Uploaded: 2021-06-10T06:58:29.000Z
Duration: 18 min 3 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

When you think of the most dominant  creatures on earth - what comes to mind?   

様態の副詞

If considering sheer size, perhaps you  immediately thought of the ocean - and the  

largest animal that's ever lived - the blue whale.  Or perhaps thinking of strength and ferocity,  

you imagined lush forests full of fearsome big  cats. Or maybe, quite sensibly, you thought of  

us - human beings- the most intelligent, and one  of the most widespread creatures on the planet.    

But if you were to walk down the sidewalk, or lean  against a tree, the first animal that you would  

likely encounter is something small - ants. Their  total population is around ten thousand trillion,  

and when combined their total weight would be  about the same as the weight of all human beings.  

in biomass and in impact on ecosystems,  these small animals are arguably the most  

successful creatures to have ever lived.     Ants have colonized almost every landmass on  

earth. Their presence is so significant that they  have directed the evolution of countless other  

plant and animal species. Aggressive, warlike,  but also cooperative, altruistic - ants living  

in colonies exhibit some of the most complex  behaviors of all insects. And the colony is the  

only thing that matters in the lives of ants.  Their loyalty to it is absolute. And in their  

service to it, they exhibit some of the most  complex social behavior in the animal kingdom,  

giving rise to their nearly complete  ecological conquest of the earth.     

How do ant societies work, and what is it about  the colony that has made ants so successful?  

Is it as simple as “strength in numbers?”  Or is it something more profound?   

Even though insects were among the first  animals to colonize land, cooperative insect  

societies are a relatively recent development.    The first insects emerged around 400 million  

years ago - but ants didn't emerge until  much later, around 100 million years ago.  

They lived amongst the dinosaurs, and for a long  time did not rule the landscape. This was the  

era of the giant dragonflies, cockroaches, and  termites. It wasn't until 60 million years ago  

that they became the dominant insects. And since  then, they have truly flourished. Today there are  

around 16,000 different species of ant, and they  are found on every continent except Antarctica.    

The competitive edge that allowed ants  to become a world-dominant group is their  

highly developed colonial existence  and specialized social structure.    

Ant societies are broken up into two castes: a  non-reproductive worker caste, and a reproductive  

royal caste. The queen is the only reproducing  female of the entire colony, and the colony  

exists to serve her, and her alone. The birth  of a colony begins with the birth of a queen.    

The life of a queen begins when its mother queen  lays a special kind of egg, different from the  

millions of regular worker eggs the queen ant  will lay in her lifetime. These special eggs  

are laid when the colony passes a certain size -  and when they hatch, they produce ants that are  

larger than regular workers and have wings. These  are the reproductive males and young queens.    

During what is called a nuptial flight  these winged ants take to the air and  

mate with each other, after which the males  die and the females drop to the ground,  

scrape off their wings and begin to search for  a place to dig their nest. Few get far in this  

journey. Predators snag most of these young  queens before they can establish themselves.  

Only around 1 in 500 new queens has a chance  at success. But those that do succeed become  

the single egg-laying queen of their new colony.   Over the course of her life, a queen ant can lay  

up to 300 million eggs, depending on the species  of ant. And the vast majority of these eggs  

hatch into dedicated worker ants - female ants  whose lives are devoted to the queen's welfare  

and reproductive activity. At any given time,  there are millions of worker ants maintaining  

the colony. There can be many different types,  and many different sizes of workers even within  

a single colony. Some care for larvae, others  excavate tunnels, others build amazing structures,  

while others leave the nest and search for  food, or go to war with neighboring colonies.    

And surprisingly, it is the ant workers themselves  who ultimately decide the fate of the young,  

choosing which worker caste they  will develop into. Larvae develop  

into different types of workers based  largely on the nutrition they receive.  

Those fed more insects than seeds are  more likely to become larger individuals.

For leaf cutter ants, the polymorphism  that exists among the workers is extreme.  

The largest workers, called soldiers, defend  the colony, while the medium sized workers  

collect leaves, excavate tunnels, or collect  garbage, and the smallest workers raise the  

young and cultivate and farm fungus - the  only food source for the whole colony.    

The workers toil away in a flawless synchrony  - in a flow that looks chaotic to our eyes,  

but is in fact based on a  complex system of communication,  

a chemical and physical language invisible  to us, but binds these societies together.    

For years, scientists knew that ants must  have some way to talk to each other in order  

to organize their intricate societies.  But ants have poor vision and hearing,  

so scientists knew that ant communication must  work in a fundamentally different way to ours.    

It was a mystery for years, but in 1962 leading  entomologist EO Wilson began to crack the code  

of ant communication. He started with the  question of how ants tell other members of  

the colony the location of a new food source. He  noticed that ants often tap their abdomen to the  

ground when travelling, so wondered if they  were leaving some sort of chemical trail.    

He began painstakingly dissecting fire ant  abdomens, crushing each of the organs with  

an applicator stick. He would then spread  the ant juice on a piece of paper in front  

of other fire ants, to see if they would react.  As he worked through each of the known organs,  

the ants showed no interest. But then he stumbled  upon an organ that had never been studied  

before - something called Dufour's gland. When he  crushed this gland and spread it across the paper,  

the ants went wild. They followed the  trail immediately and completely.   

Over time, scientists have discovered over 20  different pheromones that ants use to communicate.  

And by combining different signals, ants  have created a complex pheromonal language.   

African weaver ants, in particular, have the most  sophisticated pheromone communication system ever  

studied in animals. Some of their thoughts are  expressed by spreading pheromones on the ground,  

like previously mentioned,  combined with physical gestures.    

When a worker wishes to say 'follow me I have  found some food' she deposits a trail from the  

rectal gland, while running from the food back  to the nest. When she encounters other workers,  

she waves her head and touches the other ant  with her two antennae. Or when a worker wishes  

to raise the alarm about an enemy, she lays  short looping trails around the intruder with  

secretions from the sternal gland.    Other signals are sent through the  

air. When an African weaver ant worker  encounters an enemy in her own territory,  

she releases a mixture of four chemicals that  not only convey a message but elicit a response  

from all other workers in her vicinity.    The first tells the other ants to 'be alert'.  

The next one tells them to search for the  trouble. The next one tells them to come  

closer and bite anything in their path, and the  final compound tells them to go nuts and attack.   

Scientists believe that the combination of  these signals very closely resembles syntax  

that we see in human language. A main reason ants  are so successful in the world then, is the same  

reason that humans are. Like us, communication  gives ants the amazing capacity to cooperate.    

Of all ants, weaver ants are among the most  impressive. They dominate the forests in  

Africa and Australia, in large part due to their  complex and efficient chemical communication.  

But perhaps more remarkable than their  ability to communicate so effectively,  

is what they can achieve with it. Weaver  ants are a species of ant that do not live  

in or on the ground, but in the trees. And  to keep their huge populations safe there,  

they construct their own housing. They weave  branches and leaves together to create an  

architectural feat, full of a network of different  rooms complete with roofs, walls, and floors.    

To begin the process, a single ant searches for  a nice, bendy looking leaf. It will pull on the  

edges, testing to see if the leaf will curl.  If the ant has some measure of success, other  

ants will be attracted to the endeavor, and begin  pulling the edge as well. As the leaf bends more,  

more workers arrive. They line up in precise rows,  gripping the edge, pulling it towards another  

leaf. If the gap is too large for a single row of  ants to seal, they perform an impressive acrobatic  

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