Imagine. You’re camping in the jungle. Your camp leader has instructed you to go out into the forest to find some food. You better not come back empty-handed because otherwise you’ll be on washing-up duty. So you forage around not far from the camp, then get distracted by a beautiful butterfly and suddenly you’re lost. You don’t even know what direction you came from.
No streetsigns, no Google Earth, no reception. How you going to find your way back?
Somehow ants cope with this scenario every day. So how do they do it?
In a variety of ingenious ways as a matter of fact. Some species use pheromones to lay a trail back to the nest. Any ant who gets lost–and you can recreate this situation by simply plucking up an ant and dropping it elsewhere–will just randomly wander until they hit one of these trails. Once on the trail, only a matter of time separates the ant from its nest.
Other species will use a method called path integration to allow them to take the shortest route back to the nest. By keeping track of both its distance travelled and its direction of travel, the ant can build a mental “map” of its location in relation to the nest. Ideal for random foraging paths on the way out from the nest, followed by direct routes home with the food. Distances travelled can be measured using internal pedometers that keep count of steps taken, or by evaluating how objects change in the ant’s visual field. Directions are measured using the position of the sun, a distant “fixed” landmark, or sometimes even the Earth’s magnetic field!
This path integration method is especially important for species who forage in hostile environments where efficient return to the nest can mean the difference between life and death as ants avoid dessication, predators, and chats on the way back (not really).
It’s not always plain sailing for ant-nav though. Sometimes a group of ants will lose the pheromone trail and end up circling back on themselves. Other ants follow and soon enough the entire group is going round in endless circles. This is the fabled “ant mill” and often leads to vast hordes dying of exhaustion.
All-in-all though, ants are one of the planet’s smartest organisms–or superorganisms–and I highly recommend checking out what other amazing things they can do.
Image Credit: Wiki Commons