How do animals detect distance?

In a lovely British accent your GPS commands, “drive 34 miles on I495 until you reach exit 4.” You reset your car’s trip odometer and watch as the miles pass by. Without this handy little feature* on our car it would be quite difficult to tell how far we’ve gone. But what do animals do when they need to know how far they’ve traveled?

Desert ants count their steps.

Look closely at the picture of the desert ant above and you can see that it’s actually on stilts. To test whether or not ants count their steps, scientists ran experiments in which they lengthened (with stilts) or shortened the legs of the ants and recorded how far they ended up walking. Read about it here or watch a fun animation here.

Bees keep track of how much their visual world has moved.

Honeybees and bumble bees have been shown to use optical flow to determine distance flown. Optical flow is the movement of the visual world across the eye (learn more about that here). Scientists were able to discover this by having bees fly down tunnels with moveable walls and seeing how the wall movement changed the flight distance of the bees (read about it here).

Many animals use landmarks to gauge distances.

These homing pigeons have been shown to use landmarks to navigate (read about it here). Many animals have this ability, including bees, ants and humans.

It’s likely that most animals use some combination of the distance tracking methods listed above. In the past, research has suggested that some animals (like bees and ants) estimate their energy expenditure to determine how far they’ve traveled. Recent evidence, however, does not seem to support this hypothesis.

Distance estimation, like compass orientation which I recently wrote about, is another one of those awesome animal senses that us humans have had to recreate with technology. Right now we’re working on mimicking these animal abilities on the robots we’re building. I’ll share our progress on this in an upcoming post.


*the first odometer appeared over 2000 years ago on Roman chariots!


Photo credits: [ant: unknown, retrieved from Scientific American blog site][bees: Dan Blustein][pigeons: Robin Freeman]


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