This activity looks at how ants find their way around.
Warning: this activity involves ants, some of which have powerful jaws or stings. You should not come into direct contact with any ants as part of this activity, but if you are allergic to ant bites or stings, this is an activity to skip. With this or any activity that involves animals, you should always follow these rules:
Have an adult supervise
Take care to make sure they don't harm you
Do not harm them
Do the activity so you have the smallest possible affect on the animals
You will need
An ant colony on flat ground
Biscuit crumbs (possibly)
A cardboard or paper ring, about 20 cm across and 5-6 cm wide
What to do
Try to find an ant colony where the ants are making a trail. If you find an ant colony where the ants aren't making a trail, you could make a small pile of biscuit crumbs about a metre or so from the colony. If you wait for a while, the ants should form a line carrying the crumbs back to the colony. Ants are cold-blooded, so try to do this activity during the warmest part of the day, when they are most active.
Follow the ant trail back to the colony.
Place the ring around the food or the entrance to the colony. Be careful not to squash any ants in the process.
Watch how the ants react when they reach the cardboard.
Keep the cardboard there for several minutes and watch what the ants do.
When you have finished watching them, carefully remove the cardboard, without harming the ants.
I found that once the ants reached the cardboard, they acted as though they were lost. The ones returning to the colony with food and the ones heading out to the food started to wander around on the cardboard at random. After a few minutes, they started to form a trail again.
The ants before you put the cardboard down
Immediately after you put the cardboard down, the ants will wander around as if lost.
After a while, the ants will re-establish the trail.
What's happening?
Ants brains work differently to ours or most mammals. When ants are searching for food or taking food to the ant colony, they don't actually remember the locations of the food or colony. Instead, ants leave behind them a trail of chemicals called pheromones, which they can smell. As ants forage, or search for food, they leave one type of pheromone behind them, which they can use to find their way back to the colony. When they find food, they follow the trail back to the colony while leaving a trail of a different pheromone.
When another foraging ant finds a trail leading to food, they can follow it to find the food and take it back to the colony, while leaving their own pheromone trail. As more and more ants come across the pheromones, they make it stronger and an ant trail is formed.
When you put the cardboard down, you blocked the ants from the pheromones. Without a trail to follow, they had to go back to randomly wandering around until they could find the trail on the other side of the cardboard again. Since they couldn't go around the cardboard, they had to cross it and gradually re-established the trail.
The ants' method of using pheromone trails has some useful features:
The ants make the pheromones stronger near the starting point of the trail and gradually make them weaker as they move along. This means that when an ant comes across a trail, they can follow it to their colony or the food without going the wrong way.
The pheromones will gradually evaporate. This means the ant colony is not surrounded with old trails that don't lead to food any longer.
Ants tend to find the shortest route between the food and their colony. This is partly because if there are two trails, the ants don't take as long to travel along the shorter trail, so every minute, more ants will go along a shorter trail than a longer one. This makes the shorter trail more powerful, so the ants will prefer to use it.
