Insects are the largest single group of animals in the world. About 700,000 different kind of insects are known, and more are being discovered every year.

Insect are found almost everywhere on earth. Some live deep in underground caves, and some on the tops of the world highest mountains. There areinsects that live on surface of the ocean, far from land, some live in dry deser. Some live in hot springs whose water temperature is 120 degrees Fahrenheit.

Many different insects have been found in cold. Barren Antarctica. One insect is able to live in venegar. The young of another insect live in salty lakes. Insect can luve in a great many different kinds of places. This one of the reasons they have remained on earth for over 300,000,000 years.

Most insect5s are very small. Only a few kinds grow to more than 1 or 2 inches. Some are so tiny that they can hardly be seen. But the largest ones are bigger than some mice.

The small size insects makes it possible for them to escape their enemies by crawling into cracks or other hiding places. And because they are so small, they need very little food and water to live. Thus their small size is a very great advantage.

Anyone who touches the wings of butterfly or a moth finds that somethings like dust comes off on his fingers. The dust is actually made up of tiny scales. The scales grow in rows and give the wings their patterns of colors. The scales also account for the scientific name for butterflies and moths. Together they are called Lepidoptera, which means “scaly winged’.

They are about 112,000 different kinds of moths and butterflies in the world, and they live almost everywhere. In the United States and Canada there are probably about 700 kind of butterflies and 7,000 to 9,000 kinds of moths.

Attacking from ambush, an African lion charges a band of antelope and strikes one down with a single sledgehammer blow of its paw. Padding sil;ently through the Indian jungle, a Bengal tiger stalk an unsuspecting deer. Crouched on a limb, a South America jaguar tenses its muscles, then springs at a passing tapir.

Like all members of the cat family, these three big cats are expert trackers and hunters. They must be if they are to eat. They belong to the order Carnivora the meat eating mammals.
Cats vary in size from beasts smaller than the domestic tabby to Siberian tigers weighing 270 kilograms (600 pounds) or more. Their coats come in many colors and many striking pattern. In the wild, cats range throughout mos of the temperate regions of the world, except for Australia, Madagascar, and some of the Pacific islands.

The Arabian camel is a desert animal. If necessary, it can go without food for days at a time. He hump of the camel’s back is fat. The fat serves as stored food. The camel can also go without water for long periods of time. But scientist are just beginning to understand how it does this.
The Camel is also suited in other ways to desert life. Its broad, padded feet stay on top of sand as the camel walks. When sand blows, the camel can shut its nostrils into slits. And it has thick pads on its knees. It kneels confortably on these.

The Arabian camel is sometomes called the ship of desert. Used as a beast of burden, it can carry 270 kilograms (600 pounds). Somewhat smaller camels are raised for riding. One-humped camels are sometimes call dromedaries.
Arabian camels are mostly raised in the desert of North Africa and Arabia. They all have one hump. They eat the leaves of desert plants. That belong to the big group of animals called hoofed mammals.

Another kond of camel lives on the dry, cold plains of central Asia. This is the Bactrian camel. It has two hump on its back. It also has long hair. The Bactrian camel can carry a pack over deep snow in weather that is below –180 C(00F). It can stay alive on scrub plants that few other animals would eat. People of the Asian plains raise the camel for milk, meat, hides, and hair for making cloth.

The camel’s closest relatives are four animals of South America: the guanaco, vucuna, llama, and alpaca.

Bird are flaying animals. That it the single most important fact about them. Bird are not the only animals with the power of flight insect and bats fly; so did certain ancient reptiles. But birds are the only really numerous flaying animals that have backbones. There are about 8,600 species of bird, but fewer than 1,000 of bats. The flying reptiles have long been extinct. And insects do not have backbones.
Flight is a very difficult activity for a living thing. The strains and streses on the bones and muscles of a flying animal are tremendous. Its senses, such as those of balance and sight, must be of a special sort. Flying demands a much greater supply of energy than do most forms of getting about. Therefore birds have very special features and abilities.
For instance, only a very light animal can fly, but its supporting framework must be very strong. A bird skeleton is a simple, stiff frame work that is both light and strong.
It is light because most of the bones are thin plates or hollow, air-filled tubes and struts.
It is strong because many of these bones have special shapes; the shapes give the bones their strength, rather than the weight or thickness of the bones.
A flying animals also needs strong but flexible surfaces for wings. Feather fit this need perfectly. Overlapped like shingles, they also serve as the warmest yet lightest of insulators for these warm-blooded, flying animals. Fetahers are found only in the group of animals we call birds the class Aves.
The forelimbs (or arms) of bird serve as wings. This means that they are of little use for anything except flying. So birds must walk on two legs. They must have very flexible necks and strong beaks to care for yopung, as weapons of defense, and for many other jobs tha non flying animals do with the paws, claws, or hands on their forelimbs.

They are probably 15,000 to 20,000 different kind of bees living today. Ninety-five per cent of these various kinds are solitary bees that live alone. Five per cent are social bees that live together in colonies containing hundreds, and in some cases, thouands of members. The most social bee of all is the honeybee. It has developed a most efficient social system. Thousand of honeybees live co-operatively in hives and devide the labor of the colony.

Beavers inhabit ponds and streams in wooded areas from Alaska to northern Mexico. Their bodies are ideally constructed for their varied activities on land and the water. A beaver’s large hind feet are webbed for swimming. His broad, flat tail is scaly and naked, except for a few bristles. It seves as a prop when he stands up to gnaw on tress; it becomes an alarm signal when slapped against the water; it is rudder and an oar when he is swimming.
Though air breathers, beavers are troughly at home in the water. They can remain submerged for 15 minutes at a time. When a beaver dives, flap-like valves in his ears and nostrils close, shutting out the water. Except for his tail, the beaver is clothed in a shiny coat of soft, thick underfur; this is overlaid with longer, coarser guard hairs. Glands on either side of the tail supply oil, which keeps the coat waterproofed and glistening. The two inner claws of the beaver’s hind feet are grooved; they make efficient combs for grooming the coat and spreding the oil through it.

A shaggy giant wades into a stream. Ducking its head, it lunges forward. Then it comes up, a big salmon flopping between its jaws. Triumphant, the huge beast clambers ahore to eat its meal in comfort. This expert catcher of fish is the Alaskan brown bear the world’s largest land dwelling flesh eater. It may be nearly 3 meters (about 9 feet) long.
Alaskan brown bears feed almost entirely on fish when salmon are running upstream to spawn. T other times the bears make a meal of whatever is in season and available. They may dig for roots and bulbs and eat berries, fruit, eggs, and insect. They burrow after squirrels and other small mammals. Sometimes they even eat grass.

In the animal kingdom bats are classed as mammals, a large group that includes men, mice, lions, and dogs. Like all mammals, bats nurse their young on milk. Like most mammals, they have hair and bear living young. But in one ways bats are different from all other mammals: bats can fly.

There are mammlas knows as flaying squirrels and flaying lemurs, but they do not truly fly. Rather the glide from tree to tree. Bats are the only mammals that move through the air with wings.

A bat’s wings is not like a bird’s wings. The bird’s wing is formed chiefly of feathers; these grow out from bones that make the front edge of the wing. The bat;s wing is a double layer of skin stretched over the thin bones of its arm and fingers. A bat’s wing is something like a kite.
A bat’s skeleton is the framework for a living flying machine. The arm extends from a shoulder socket, bends at the elbow, and ends with long, slender fingers. The fingers are almost as long as the rest of the body. They support the main part of the wing and are webbed. These webbed fingers account fior the bat’s scientific name, chiroptera, meaning “wing-handed.”
The wing covers all fingers except a short thumb, which is left free. A sharp claw on the end of the thumb forms a hook at the top of the wing. When its wings are folded, the bat uses its hooks to climb tree trunks, rocky walls, and other rough surfaces.
The skin connecting the webbed fingers is also attached to the bat’s clawed feet. This makes the back part of the wings. Most bats have an extra flap of skin connecting their feet. While flaying, many can fold this flap into a pocket for cathing insects.
Since its legs bones and leg muscles are included in its wings, a bat can fly more easily than it can walk. But the feet are far from useless. Like human hands, a bat’s feet can turn inward, which enables them to grasp objects like twigs, and branches. Sharp claws hook securely into crack or around bumps in the wall or ceiling of a cave. These claws are so strong that they support the bat’s whole weight, even during sleep.
When resting, a bat can use its claws to cling to a wall or tree trunk-or it may hang upside down, suspended by its feet. Bats hang upside down because it is easier for them than perching upright. Their small legs are attached to the body in a way that makes perching in awkward.

Bacteria are probably the most common form of life on earth. They are also among the simplest and smallest living things. They are micro-organism, which mean they can seen only under a microscope.
Some bacteria cause disease, but most do not. There are at least 2,000 species of bacteria. Most of them are harmless or helpful to other forms of life, including people.
What is bacteria live?
Bacteria are everywhere. Some live in the mouths, and intestines of animals and of people. Other live on fallen leaves or animal waster; in water, milk, and most food;and on dust and soil. Some bacteria can use hydrogen gas, ammonia, and iron compounds as their food. A few bacteria feed on gases and acids that are poisonous to us.
Most bacteria are killed by heat, yet there are a few kinds that live in hot springs, Freezing does not usually kill bacteria, but it checks their growth. Some kinds of bacteria, but resist drying, strong chemicals, or extreme temperatures by changing into tough-walled spores. The cabteria may last a very long time in this resting form. Under favorable condition, the spores walls burst, and the bacteria become active again.
New and future uses of bacteria
Scientist are finding many ways of making bacteria work for the benefit of people. For example, they have developed a method for producing methane gas by processing the manure (solid wastes) of cattle. Methane is valuable fuel. Like natural gas, it is used for heating homes and factories, and for other energy needs. In the same process, protein and minerals are extracted to be used for cattle feed. Protein rich cattle feed has also been obtained by growing bacteria on wood petroleum, abd sewage wastes.
Some bacteria are used as living insecticides against certaian insect pests.
Scientists are experimenting to find answers to questions such as these; May bacteria useful in fighting other bacteria able to make cellulose, which can be used to make paper? Can bacteria that eat holes in underground deposits of limestone be used to make oil flow more easily? Can bacteria be used to generate electricity? While feeding on certain subtance, some bacteria produce energi that can be converted to electricity. Scientists are traying to devise batteries that can use bacterial energy.