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On the Wild Side: Strange news from the World of Wildlife!


Animal, Vegetable, or ... Velcro!?!
© Paul D. Stewart

Animal, Vegetable, or . . . Velcro!?!

It looks like a convention of aliens has landed. But we're not sure even Steven Spielberg could have dreamed up these organisms! Can you guess what they are? Denizens of the coral reef? Exotic funghi? Some sort of plant-animal mutants? Here's a hint: They could be the key to the next revolution in adhesive products (think Post-it Notes and Velcro).

Have you guessed what the objects in the photograph are? They may look like extraterrestrials, but what they are is the feet of six of the world's 750 species of geckos, thin-skinned lizards that live throughout the tropics. Geckos, to put it simply, have truly amazing feet. Humans have been trying to get to the bottom of gecko feet for centuries. Why? Because geckos can skitter across any surface, horizontal or vertical, right-side up or upside down, be it a rock, a plaster wall, a tree branch, a leaf, or a pane of glass, without falling off. They stick so well that they can even hang by a single toe, if so inclined.

Theories about gecko stickiness have abounded over the years. It was thought that their toes acted like suction cups, that there was chemical bonding involved, that the adhesive attraction had to do with water molecules. Recently, scientists have finally discovered just what it is that makes a gecko stick. On the bottom of each gecko toe pad are scales covered with a myriad of microscopic hairlike bristles, millions of them. Each tiny bristle is in turn covered with about a thousand minute pads -- and we mean minute: each pad is said to be only 200-billionths of a meter wide. These pads are just the right size and shape to bond on the molecular level with molecules on the surface material. The force of attraction at work is called van der Waals force.

Now that scientists have discovered the key to this miraculous adhesive, they have been developing synthetic "gecko feet" in order to study its properties and explore possible applications. Eventually they hope to invent an adhesive that can be used far and wide, wet and dry, everywhere from under water to outer space.

Click here to learn about the geckos of North America.

 

 

 

 

 

2007 eNature.com