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Bats | |
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Introduction A bat looks like a mouse because of its small, furry body. Some thought that a bat was a flying mouse so they named them "flittermouse". Others believed that bats were birds. A Roman fable tells the following story: The bird council passed a law forbidding all bats from the kingdom. The bats said that they were mice. When the bird council banned mice, the bats claimed they were birds. All the beasts became angry so the bats were afraid for their lives. From then on they only flew at night. Today we know that a bat is not a mouse or bird. The bats are more closely related to primates. Bats fly like a bird but they do not have feathers, build nests, or lay eggs. Bats are mammals. Their bodies are covered with fur. They are not hatched from an egg but are born live. They drink milk from their mothers as babies.
There are 1,000 species of bats that live all over the earth. They live in all parts of the world except in most of the Arctic and Antarctica. The greatest variety of bats live in South and Central America. The largest number live in Africa. In the United States there are 43 different species. More bats are found in the tropics than any other mammal. Flight Bats fly with expertise. They are able to truly fly. There are almost 4,000 mammal species. Bats are the only mammals capable of powered flight. The bat's body is designed for flight. The neck is short, the chest is large and strong, and the abdomen is narrow. In a bat the wings have a wide, thin surface which we call an airfoil in flight terms. The wings also give the power to the bat to move through the air. In flight terms we call this the propulsion system. The wing of the bat is made of bones that are like the bones in our arm and hand. The name of this animal order is "chiroptera". In Greek this means handwing. The bones of the bat are covered with a double layer of thin skin called a membrane. The membrane is so thin that you can see light through it. The membrane on the bat covers the arm bones and finger bones. It extends to the sides of the body and leg making an airfoil surface. In some bats the membrane is between the legs, including the tail. The small thumbs do not have the membrane on it. This is so the bat can climb. The wing has a stiff leading edge like an airplane. This is made by the second and third fingers with the membrane in between. The third finger creates the wing tip. The membrane that covers the tail of a bat slows it down. Many of the bat species do not have the membrane covering their tail. Those who do have the membrane on the tail use it as a pouch when catching insects. Bats fly through the air in a rowing motion. During the downstroke of the bat's wings both the thrust and lift are achieved. On the downstroke the wing moves backwards and upwards. Then the wings are swung outwards and downwards. And last, they are moved forward with the tips almost touching in front of the head. This makes the shape of an open umbrella. The bats have large, strong muscles in their backs and chests. These provide powerful wing strokes which enable flight. Some of these muscles pull the wing up and others bring them down. The bat's wings move like webbed hands. In this way the wings can change shape quickly. Many bats can fly in a hovering manner like hummingbirds or helicopters. Other bats enjoy gliding flight for short periods of time. Bats use their wings to brake and steer by folding one wing. Microbats/Megabats The two main bat groups are microbats and megabats in the animal order, chiroptera. Microbats is the larger bat group with 700 species. They live in the Americas, Asia, Europe, Africa, and Australia. They are smaller in size with complex ears and small eyes. These eyes we believe can only see black and white. The microbats use listening to echoes to find objects and to hunt for their diet of insects. This is called "echolocation". Echolocation is like radar in planes. The bat sends out beeps through the air. These hit an object and bounce back as echoes. The bat hears the echoes and the brain works out a sound picture of the object. The large ears and nose also help. Children can sometimes hear the ultrasonic beeps of bats. Adults cannot. The microbats have a smaller wing area than their body. They increase the number of wing strokes to fly. Each second they move their wings up and down 11-18 times. They hunt in the area where they live for insects. Megabats have about 170 different species. They live in the tropical areas of Africa, Asia, and Australia. These bats are larger with simple ears and large, dog-like eyes. They use their very clear vision and sense of smell to find nectar, pollen, and fruit to eat. They do not have the echolocation ability. The wing area is larger than their body size in the megabats. The air resistance on its large wings causes the megabats to be slow and bulky in flight. But with the long, narrow wings the megabats travel 50-80 km in one night. Bats Today Barns, attics, caves, and hollow trees are the homes of bats. They usually live in small groups. The size of a colony can number hundreds of thousands. Bats usually do most of their flying at night. They use their wings to catch insects as they fly and their tails as well. Many bats eat about half of their weight in insects in one night. A little brown bat can eat up to 600 insects in an hour. A colony can rid 6,000 tons of insects in a year. Tropical bats transfer pollen as they fly from plant to plant. This contributes to growing plants. They eat bananas, mangoes, guavas, and berries in 15-20 minutes. Then they pass the seeds of the fruit while flying. Often this reseeds areas of the rain forest. In the Southwest of the United States cactus plants are dependent on bats for pollination at night. Desert animals need these plants for survival. If there were not bats these plants and animals would not live. The hog-nosed bats of Thailand are the smallest bats. They are also the tiniest mammal in the world. They are about the size of a bumblebee and weigh less than an ounce. They have the wingspan of about 5 inches. Many people think that bats are dirty and linked with evil forces of darkness. This is not true. Bats are very clean animals who groom their wings and teeth daily. They do not carry more rabies than other mammals. Other people believe that Count Dracula turns into a bat. This is only a myth. Vampire bats live in Mexico and Central and South America. They do not suck people's blood. They do feed on the blood of sleeping cattle and livestock. Bats are very helpful to man and the environment. They are fascinating mammals that cover most of the globe.
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