Why do ants touch each other with their heads when they meet? Why do they walk in a file one behind another?

At some point in our lives or another, we watched ants march on the kitchen floor, across the walls of our house, or on the front yard garden. No wonder as these pesky little creatures possess such a fascinating behavior. But why do they touch each other’s heads or walk in a file? 

First, there are over 10,000 different species of ants on the planet that we currently know of. They bump into each other when they meet as it serves as a way of their communication. Whenever they want to alert or inform about something that might be beneficial for their colony, they utilize their antennae to pick up or transfer the scent. By doing so, they are able to smell the new scent and pass on their discovery.

Some studies show that ants also bump into each other when communicating about possible areas they can use new nesting sites. In case they need to migrate, ants send out explorers to look for locations fit for the colony. Once the explorers find a suitable place, it will relay the message to another ant to survey or inspect the area. If it finds it suitable, it will go back to the colony to inform the other ants and check the site themselves.

As they pass the message, the frequency of bumping into each or touching each others’ antennae increases among the colony members. Moreover, the more times they meet, means more ants agree to the new nesting site.

In terms of body language, ants also brush themselves off each other lightly to elicit a jaw reflex, which then enables them to know what they have eaten. Moreover, though we can’t hear the sound they create, ants also communicate with one another by rubbing their legs against their bodies.

Now, when it comes to those ant trails that seemed going on for hours, the unique chemical signals, pheromones, are also responsible for them. When a worker ant goes out to search for food, it leaves a trail of pheromones, which other ants may use to follow.

If the worker ant became successful in finding food, it will return to the colony and will leave another line of pheromones. Fellow colony members will detect the scent and follow the same path. As other ants go, they release their own pheromones, allowing the track to become stronger and more appealing to other ant workers.

Ants can quickly distinguish how well a path has been traveled depending on the thickness of the pheromone track. A thick pheromone trail implies that the destination has an abundant source of food for the colony. What’s remarkable is that some ants species have a separate alarm pheromone that they use to signal others that their fellow sisters have died, killed, or been injured.

If in case the trail has been disrupted or blocked (like we intentionally do as kids to see how ants would react), they will start walking in circles to search for other pheromone tracks and follow that again. While they are good at leaving markers, they are as good as looking for different trails left by their fellow ants.

More Readings:

Ant (Wikipedia)

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