The Tail of the Agama Lizard

THE agama jumps from a horizontal surface onto a vertical wall with ease. But if that surface is slippery, the lizard loses its footing, yet it still makes a successful landing on the wall. How? The secret is in the lizard’s tail.

Consider: When agamas jump from a coarse surface—which provides grip—they first stabilize their body and keep their tail downward. This helps them to jump at the correct angle. When on a slippery surface, though, the lizards tend to stumble and jump at the wrong angle. However, in midair, they correct the angle of their body by flicking their tail upward. The process is intricate. “Lizards must actively adjust the angle of their tails just right to remain upright,” says a report released by the University of California, Berkeley. The more slippery the platform, the more the lizard must raise its tail to ensure a safe landing.

The agama’s tail may help engineers design more-agile robotic vehicles that can be used to search for survivors in the aftermath of an earthquake or other catastrophe. “Robots are not nearly as agile as animals,” says researcher Thomas Libby, “so anything that can make a robot more stable is an advancement.”

What do you think? Did the agama’s tail come about by evolution? Or was it designed?

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