Nature's Flight

Bats--there are more than 1,000 different kinds ranging from the large flying fox to the tiny hog-nosed bat (weighing 2 grams, it's the smallest known mammal). Bats are the only mammals that can truly fly. Most bats are great flyers. Their webbed hands act like wings. Tails are used for balance and to help with sudden turns. Some bats can even use their tail membranes as brakes. (Note: Squirrels, fish, lizards, and snakes that appear to "fly" are really just gliding.)



	Ostriches aside, most birds are well-adapted for flight. They have light skeletons (thanks to hollow or very thin bones), aerodynamic feathers, and large wing muscles. And they might just have a genetic advantage too. Scientists knew that bird cells have less DNA than cells of reptiles and mammals, they just didn't really know why. Austin and Marianne Hughes of Pennsylvania State University believe that it may be a special adaptation for flight. Smaller cells can absorb oxygen more efficiently and use it to get more energy from food. That would make the energy-intensive job of flying easier for birds. The Hughes back up their study by pointing out that bats (the only flying mammals) have less DNA than other mammals. Their study is not completely finished, but it sure makes you say "hmm". (DNA is "deoxyribonucleic acid" (no wonder we shorten the name). We sometimes call this chemical substance "the blueprint for life", because it directs protein production and contains genetic information passed on to new cells. Every cell in your body contains DNA which has enough information to produce thousands of different proteins!)

Some hummingbirds can beat their wings 90 times per second (that's why they make a humming sound)! They are the only bird that can fly backwards, and they can even fly upside-down. A hovering hummingbird burns up energy about 10 times as fast as a person running.

Some time during the Devonian period (400 million years ago) winged insects appeared. That makes them the world's first flyers. Most adult insects have two sets of wings. Did you know that a mosquito beats its wings up to 800 times per second! No wonder they make such a racket when they buzz around your ear!

Canada Geese have the right idea when it comes to flying. They fly in a V-shaped formation that allows them to get lift from air currents coming off the wing tips of the bird flying ahead. In the V formation, the geese can fly up to 71 percent farther than if they flew alone!

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