Why Insects Can Float on Water?

There are some known species of little-insects can walk on water, or better known by the term "water strider" (henceforth, be called a "insect"). Although the water level seem to look flat to the human eye, for small creatures such as insects, water will seem like a "wall" which is pretty big. This wall is created by what is called the surface tension of water. To walk on water, the insects need only climb this wall. However, in order to climb the wall, legs needed a very special structure which is only possessed by these insects.

Hairy legs structure that help little 
insects can float on water. (Picture from:  
http://www.anneahira.com/)

The ability of insects to walk on water is a skill that is developed by insects to find place to lay eggs or to avoid predators. Previously, scientists initially thought that the ability of insects to float on the water just seems to be caused by the presence of materials such as wax released by insect legs and combined with the surface tension of water. But now scientists have finally discovered how little insects walking on the actual surface of the water.

Mosquitoes laying eggs in the water.
(Picture from:  http://aktifisika.wordpress.com/)

Microscopic images of insects leg revealed that insects have a very small fine hair, called "microsetae". Hair were arranged towards one direction and consists of several layers. Microsetae shaped like needle has a diameter of less than 3 micrometers, compared with the diameter of a human hair that can reach 80-100 micrometers. Microsetae addition, there is also an insect leg indentations smaller again.

Structure of legs like this will give the effect of a hydrophobic (water-repellent) are very strong and can withstand the load when the insects floating on the water. That scientists refer to as the insect leg superhidrofobik. Because of dense layers microsetae and indentations there, the air will be trapped. Air trapped in the space contained between microsetae and nano-sized grooves will form a kind of air cushion, which prevents insects feet wet by water. In addition, the structure of the foot like this, insects can also withstand loads equal to 15 times its body weight without sinking.

Water striders using surface tension 
when mating. (Picture from:  http://en.wikipedia.org/)

Insects also appear constantly move back and forth when it floats. This is done to avoid his body submerged in the water. Because these insects hovering over the water by using their legs like oars. And it is very important that these insects are not wet feet, because their feet to avoid penetrating the surface tension of water as long as they are "rowing". If their feet accidentally fall through the surface of the water, they have to produce ten times the strength of their weight to return to the surface.

This insect is also known as rapid movement, it can reach speeds of 1.5 m/s, the speed is very high considering the relatively small body size. To move, the insects will hit the surface of the water with a couple feet without penetrating the middle surface of the water, then forming depressions in the surface of the water. This basin deep enough to push the insect forward and make these insects off with a fairly high speed. *** [LIVESCIENCE | PIKIRAN RAKYAT 30082012]
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