The Ants Come Marching
I have often wondered if ants have some way to tell other ants that there’s work to be done.
You may think so, too, if you’ve watched an ant trying to lift a dead grasshopper or drag away a large crumb of cake. It struggles for a while, then dashes away. Soon a team of workers appear. The ants pick up the food and haul it off.
What’s more, you may have noticed that when two ants meet, they stop, wave their antennae, and then touch each other’s antennae. They seem to be saying, “Give me a high two.” And sometimes they seem to kiss!
Benjamin Franklin wondered about the same things more than two hundred years ago. In fact, he tried an experiment and found an answer.
A
Founding Father
Mr. Franklin is remembered as a scientist, inventor, printer,
writer, and one of our country’s important early leaders.
His ant experiment is just one of many interesting stories
from his life.
One day he discovered ants crawling all over his kitchen shelf. Within minutes, a little jar of molasses was alive with them. He picked up the container and took out the pests.
But one ant stayed inside, swallowing the sweet, sticky syrup and storing it in the pouch, or crop, inside her mouth. (All worker ants are females.)
Because Mr. Franklin wanted to know if ants could communicate with one another, he gave this ant a challenge. He tied a piece of string around the mouth of the jar and hung it on a nail in the ceiling. Then he settled down to wait and watch.
Shortly, the insect crawled up the inside of the container, over the rim, and down the side.
But when she reached the bottom, there was, of course, no shelf! The ant dashed here and there and round and round. She zigged and zagged and eventually found the string.
Then a fast march up, a dash across the ceiling, and a race down the wall and over the floor led her to an opening that let her out of the kitchen. She vanished.
About thirty minutes later, Mr. Franklin spotted an army of ants moving like running water toward the wall. They swarmed up, flowed across the ceiling, and scrambled over to the nail holding the string. They lined up and marched, one after another, down the string and into the jar.
Before long, there were two lines of ants on the string, one line tramping down to get at the sweet food, and the other line parading upward. They were carrying home globs of molasses in their crops.
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When
it comes to teamwork, ants are among
the most cooperative creatures. This group worked steadily until they had taken home all of this bit of apple pastry. (Photo by Chris Dietel) |
Ant
Language
Ben Franklin’s experiment proved that the ant had communicated
with her nestmates. But how? Did she speak to them, or did
she draw signs with her feelers? Two hundred years ago no
one knew. Today, after many observations and experiments,
scientists have found answers to some of these questions.
Ants may not be able to speak, but they can use their antennae to smell and taste. Special glands in their bodies produce a variety of odor signals, called pheromones (FEH-ruh-moans).
Using one of these signals, a scout ant can leave an invisible trail of odor for other ants to follow. And when ants “sniff” along a trail of this stuff, they receive a message. One trail’s message may say, “Come get food.” Another could say, “Prepare for battle! Alien ants on the way!”
When a scout finds food, she rushes back to the colony, spraying a pheromone trail along the way. Inside the nest, the scout performs a dance for her sisters that seems to say, “Let’s go!”
Then worker ants follow her trail. Hundreds upon hundreds of them stream out to follow the chemical trail. They scurry off directly to retrieve the food.
Ant
Greetings
Ants also exchange information with their antennae, which
serve as both nose and fingertips. When ants meet on a trail,
they wave their feelers back and forth, touching, stroking,
and tapping one another. They are searching for smells that
identify a friendly nestmate or a hostile stranger.
If the ants are sisters, one may signal the other that she needs nourishment. Then the sister spreads her antennae, opens her mandibles, and brings up food from her crop for her sister to eat.
As Ben Franklin suspected, ants really do communicate. By means of body language and chemistry, ants tell one another what they need to do, and they do it! This great spirit of cooperation is what keeps them marching.
