AAAS

Video: ‘Blindfolded’ ants reveal clues to insect navigation

Scavenging Cataglyphis ants scuttle across the scorching sands of the Sahara Desert in search of dead spiders and other arthropods to feed their colony with. The conditions are so harsh, the ants have to be efficient navigators while zipping to and from the nest to avoid being burnt to a crisp. Previous work has shown that the insects count their steps to gauge how far they’ve traveled, but a study published online today in Science indicates they can also find their way home solely with vision. They use “optic flow,” which is akin to how we estimate distance and direction out the window when riding in a car. To figure this out, researchers “blindfolded” ants with bright yellow paint to see whether they could find their way back to the colony. Experienced foragers that walked a set distance from the nest were able to return without issue, blindfolded or not, because they counted the steps it took to get to that point. But, as seen in the video above, interior colony workers—which only venture outside when carried by a forager to a satellite nest—were carried the same distance that their foraging counterparts walked, and were only able to get back unblindfolded. Although the interior workers didn’t know how many steps away their home was, they were able to rely on sight to return—which is a surprise, because vision was only thought to play a supporting role in navigation. Researchers think these ants’ Saharan habitat is so hazardous that they evolved two separate mechanisms—step counting and optic flow—to cope.