Size Matters for Geckos and Flies

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Size matters for geckos’ and flies’ glue pads, as described in New Scientist, 6 September 2003, p22. Geckos, flies and some spiders are able to walk upside down by using tiny flat pads on their feet called spatulae. The spatulae form temporary atomic bonds with what ever surface they are walking on. Biologists were puzzled that the size of the spatulae was larger in small light creatures such as flies compared with larger, heavier creatures such as geckos. Eduard Arzt from the Max Planck Institute has solved the problem by examining the spatulae of insects, spiders and geckos with an electron microscope and found that by making them smaller they could pack them more densely which increased the bonding power of the geckos toes and enabled them to carry a much larger weight.

Editorial Comment: This is a good example of how all aspects of a system have to work before the system can work. It is not enough just to have the right material in the stick-on pads. They must be the right size and density. Also, the animal has to be able to place them in the stick-on position and be able to release them when it wants to move on. We also wonder what could have made any half evolved geckos and flies try walking upside down on ceilings, branches, cave roofs, when there was every chance they would fall off. It is far more logical to believe that the God who designed flies and geckos knew how much stick-on power they would need and gave them the right size, number and density of spatulae for it. (Ref. gecko, insect, spatulae)

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