Avi Blizovsky
New research reveals that the desert ant uses a "pedometer" to measure walking distances. The researchers knew that insects looking for food could navigate their way using light from the sky, but were amazed by the ability of these animals to estimate the mileage they had traveled on the ground.
By manipulating the length of the legs of desert ants, to make them take short or long steps, team members from Germany and Switzerland found that ants "count" steps to estimate distances. The study was published in the journal Science.
Cataglyphis fortis, or Sahara ants, crawl long distances across the sandy plains of the Sahara desert in search of food. These creatures are endowed with an impressive ability to return to their nests, in a straight path, rather than retracing their steps, a move that requires the ants to measure directions and distances. Researchers know that the ants use the sky to find directions, but how they estimate distance remains a mystery.
To investigate this, scientists from the University of Ulm, Germany, and the University of Zurich, Switzerland, placed ants along a straight tunnel. When they reached food, their legs were lengthened with the help of "crutches", or shortened by partial amputation. After this treatment, the ants were returned to the food point, and began their journey back home. It turned out that the ants with extended legs continued to walk beyond the nest and the ants with shortened legs looked for it in a closer place.
The researchers who followed the "foot-care" ants and discovered that the estimation of the distance in subsequent journeys along the same route was much more accurate, came to the conclusion that the length of the steps is the important variable.
Prof. Harold Wolff, author of the article and a neurobiologist from Ulam University, says: "This means that the animals "count" their steps, a kind of pedometer. When we shortened their legs, they took more steps to get to the food and knew how to estimate that they would need the same number of steps to get back.
In the next step, we have to examine the control of the leg movement in the act of walking, to see if there is something that can act as a distance meter in these animals."
For news at the BBC
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