Halloween is upon us, which means it’s time to pick out a costume and make sure the house has candy for when the neighborhood children arrive. In the spirit of of the holiday, researchers at Tel Aviv University explain how they’ve turned trickery and disguise into a science.
Dr. Gal Ribak of the Department of Zoology at the The George S. Wise Faculty of Life Sciences, studies the biomechanics of animal movement. He uses models and simulations to try and understand how animals develop their unique style of movement, while referencing physiology, ecology and animal evolution.
Dr. Ribak says trickery is part of the job. “We use trickery all the time. One of the studies in my lab deals with the interception mechanism of damselfies – a type of dragonfly – who chase their prey while airborne. The damselfly detects moving prey visually and can calculate a flight path to intercept the prey at its future position. This allows the damselfly to capture its prey with great efficiency, while it and its prey are moving through the air.
Using artificial prey in his lab, Ribak tricks the damselflies
To understand how damselflies do this, we ‘trick’ them into chasing artificial targets in my lab, which are moved through electro-mechanical means. By controlling the motion of the target and analyzing the movement of the damselfly with special cameras, we can learn about its strategies of attack. This helps us understand the neurobiological mechanisms of controlled movement in animals, and could have implications for how we control movement in robots and drones.”
The lab of Prof. Arnon Lotem of the Department of Zoology also uses trickery and deception in the name of science. Prof. Lotem and his students study the evolution of behavioral mechanisms and social learning in animals, specifically in house sparrows.
“Behavior and leaning in animals are complex processes and understanding of these processes requires experimentation, not just observation. The problem is that in order to perform controlled experiments you have to control the behavior of certain individuals in the group and see how other individuals react to it.
Fake sparrow teaches chicks
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In studying the house sparrow, we use stuffed sparrows that are operated like a puppet on a string at a puppet show. My students specializing in this are Edit Katsnelson, Amos Belmaker and Noa Truskanov. For example, by stationing “fake,” stuffed sparrows near sources of food, the researchers managed to gradually turn hardworking sparrows, who look for food on their own, into ones that tended to follow other individuals in the flock.
In a different experiment, sparrow chicks were raised to follow a stuffed sparrow as though it was their biological mother. This allowed us to learn a lot about the way young sparrows learn from their mothers, especially about the relationship between cues in their environment and the presence of food. It turns out that when the mother only hints at the location of sustenance and allows her chicks to find the food on their own, they learn the food-related cues better than if the mother reveals the food for them.”
No one hesitates to use trickery to learn about the secret lives of bats in the lab of Tel Aviv University’s “bat man”, Dr. Yossi Yovel of the George S. Wise Faculty of Life Sciences and Sagol School of Neuroscience.
Hitting a wall
“Bats use sonar – they emit sound pulses and analyze the echoes with their brain to ‘see’ the world. In one of our experiments bats fly in complete darkness through a corridor that’s blocked halfway through by a plastic wall. The bats approach the wall and use sonar to sense it. They get strong echoes from the wall and try to land on it, but sometimes the barrier is only ‘pretending’ to be a wall. When the wall turns from hard plastic into soft sponge, it reflects fewer echoes and bats fly at it as if it there were no barrier there at all.
That’s despite the fact that in nature bats can hunt mosquitoes, which generate even weaker echoes! Our conclusion is that the different aspects of an object have to match up in order for us to perceive the objects correctly. A large wall must generate strong echoes, otherwise it’s not a wall. A mosquito is tiny and must generate very weak echoes, otherwise it’s not a mosquito. For us humans, an apple must be both round and red (or green) to be an apple. Each characteristic separately is not enough.”
An integral part of the work these researchers involves to simulating and imitating conditions in the field in order to study behavior in laboratory conditions. This requires a lot of creativity and imagination. In a sense, in many labs across Tel Aviv University – every day is Halloween.