When climbing over a ladder, the grasshopper looks closely at each rung, rather than relying on its tactile sensors. So far, science has assumed that only mammals with their larger brains use vision to walk in critical environments. Photo: Jeremy Niven, University of Cambridge
Reading aloud Even a small brain copes with complex tasks: In tough ground conditions, insects do not simply feel their way through their antennae, but look for a secure hold with their eyes. Scientists led by Jeremy Niven of the University of Cambridge have now come up with desert grasshoppers for the first time in mammals with their sophisticated brain. They sent the insects over a small ladder and filmed the climb with a high-speed camera. It was noticeable that the grasshoppers stopped suddenly when they did not see the foreleg, with which they wanted to reach the next rung: For the critical step they used the leg, which was in their field of vision. The cleverly controlled locomotion of insects on the ground has hitherto been hidden from scientists because they focused on the role of sight in insect flight. The researchers, study author Niven noticed that bees or flies have large eyes and short antennae, crawling insects like crickets or cockroaches, on the other hand, small visual and long tactile organs. In order to find out if the soil dwellers also use their eyes in locomotion, the scientists chose the desert grasshopper as a candidate for their ladder experiment: it stays on the ground and in the air, their organs are short and their eyes are large, When climbing over the sprouts of the tiny ladder, the grasshoppers underwent just as many missteps as in simple environments. The reason for this surefootedness revealed the high-speed camera: The insects use only the front leg, for which they see a secure fit.

"The use of the eyes in locomotion proves a behavior in insects, which we have found so far only in living beings with a large brain and multilayered motion control such as human, monkey or octopus, " explains Niven. "These mammals have more neurons in their visual system than the grasshoppers in their entire nervous system." The example demonstrates how nature forms completely different strategies in living beings for solving similar tasks.

That grasshoppers with a very simple mechanism prevent stumbling, also interested in two scientific disciplines beyond biology: The insects are considered in neurology for over 40 years as a model organism for the study of limb control. Robotics is also learning the tricks of how to control the legs of mechanical beings from insect crawling.

Jeremy Niven (University of Cambridge, Cambridge) et al .: Current Biology, doi: 10.1016 / j.cub.2009.10.079 ddp / science.de? Rochus Rademacher advertisement

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