Page 156 - Engineering in Nature

Engineering in Nature

The gecko does not cling to the ceiling by secreting an adhesive
substance, since the lizard has no glands with which to do such a
thing. Furthermore, such a system might also stick the gecko to a sur-
face, but not allow it to move.
Nor does the reptile's ability stem from a structure like a suction
cup. The gecko's feet also work perfectly in a vacuum, and a suction
cup cannot attach itself to the ceiling in such an environment.
Neither is there any question of electrostatic attraction.
Experiments have proven that the gecko's feet function even in ion-
charged air. Were electrostatic attraction being used, the ions added to
the air diminish the force of attraction and prevent the lizard holding
on.
Research has shown that the mechanism in the gecko's feet is an
example of superior engineering. In fact, the lizard's entire foot has
been designed for climbing.
Kellar Autumn, an environmental physiologist from the Lewis &
Clark High School in Portland, and the California Berkeley
University bio-engineer Robert Full, and supported by Massachusetts
IS Robotics, set up a team to perform a microscopic study of the geck-
o's climbing ability. 46
The results revealed that in the gecko's feet is a force of which per-
haps only nuclear physicists are aware.

Special Feet Consisting of Thousands of Micro-Hairs
The tips of the gecko's toes are covered with thin leaves of skin,
just like the pages of a book. Every leaf, in turn, is covered in a special
tissue known as setae, hair-like protuberances, whose ends are di-
vided into thousands of microscopic tips.
On the gecko's toe, an area the size of a pinhead contains an aver-
age of 5,000 micro-hairs. That means each of the animal's feet contains

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