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Name: Justiene
Status: other
Grade:
Location: HI
Date: May 2007

Question:
How do insects such as the house fly stay in flight without using much energy? What structures allow for this fact?



Replies:
Actually, insects use a lot of energy compared to their body weight. And even though it may seem like house flies never land, they actually land frequently. Few insects can maintain long, sustained flight.

Still, insects' ability to fly as long as they do, and with the speed and agility that they have, is truly impressive. Insects have evolved over thousands of years to be able to fly how they do.

Their bodies are optimized for flight in several ways. First, the muscles insects use to move their wings have some of the highest power-to-weight ratios of any living thing. Second, their bodies are designed to transport air (oxygen) to those muscles extremely efficiently -- whereas people have small lungs and air gets to our muscles via blood, insects have rigid air-filled tubes and sacs in their bodies that actively pump oxygen to the muscles. There is only a thin barrier between these sacs (and a small amount of blood-like liquid) and the muscle that the oxygen has to move through. As the wings pump back and forth, the sacs compress and inflate creating a bellows-like effect. Lastly, as the insects fly, their forward flight velocity helps further to increase the pressure pushing oxygen toward the muscles. The overall result is that insects' bodies can deliver much more oxygen to their muscles, and the muscles use every bit of it.

Insect wings are truly remarkable and efficient as well. It's only been in the last few years that scientists have figured out how insects fly (have you ever heard that "according to engineering calculations, bumble bees shouldn't be able to fly"?). It turns out that the dynamics of flying depend on the size of the thing doing the flying. The physical rules for flight for a jet airplane are different than they are for a bird, and different for a tiny insect. When you're really small, air seems "thicker" -- or, more precisely, the viscosity of air plays a more influential role on flight than its density. What this means is that insects can generate lift more efficiently (with less energy) than larger things (like planes or even birds). Unlike planes (fixed wing), or even birds (a different kind of flapping), insects' wings create unique air vortices that create more lift. The mechanics of insect flight are different than bird flight due to their size differences. The shape, length, and thickness of insect wings are all optimized for the size, speed, and agility that insect requires. Insect wings also are remarkably strong and light considering the forces that they have to bear. Again, this is a function of size. Nature has created some unique nanotechnology allowing insect wings to be very strong, light, and effective.

So, in summary, insects can fly very well for these reasons:

1. The physics of flying are different for insects

2. Insects' bodies are optimized for oxygen transport to the muscles

3. Insects' muscles have huge power output

4. Insects' wings are optimized for their unique kind of flight

Hope this helps,

Burr

http://en.wikipedia.org/wiki/Insect_flight



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