Snakes

(MS.Encarta) - Put yourself in the place of a harmless snake. You’re just lying in the grass, minding your own business, when suddenly a great big foot comes crashing down right next to your head. You take off through the grass like greased lightning. In the distance someone screams, “Snake!” Which one should be more afraid, the human or the snake?

A snake is simply a long, thin animal. It does not have arms or legs. It crawls along the ground on its belly.

Snakes are reptiles. Like all reptiles, snakes are cold-blooded. They can’t control their own body temperature, and so they have to lie in the sun to get warm and in the shade to get cool.

WHERE DO SNAKES LIVE?

Snakes live almost everywhere in the world. They live in grasslands, deserts, and rain forests. Some snakes live in water. There are no snakes, however, in Ireland, Iceland, Antarctica, or New Zealand. There are more than 2,500 species (kinds) of snakes.

HOW BIG ARE SNAKES?

The world’s smallest snake is about 5 inches (about 13 centimeters) long at full growth and weighs less than 0.1 ounce (less than 2 grams). The largest snakes are the anaconda and the reticulated python. They both can grow as long as 33 feet (10 meters) and can weigh up to 550 pounds (250 kilograms).

DO SNAKES HAVE BONES?

Like other reptiles, snakes are vertebrates—they have a backbone. A snake’s long backbone is made up of small bones called vertebrae. Snakes have between 100 and 400 vertebrae. Humans have just 32 vertebrae.

A snake’s jawbones are not attached to its skull. They are linked together by muscles and stretchy tissues called ligaments. This type of jaw lets a snake open its mouth wide and eat animals that are much larger than its head!

A SNAKE’S SKIN

The dry outer layer of a snake’s skin is made of scales. Scales give a snake its color. The color of some snakes lets them blend into their surroundings and avoid being seen. Some poisonous snakes are brightly colored to warn off enemies.

Snakes regularly shed their skin. First, a new layer of skin forms underneath the old one. Then the snake loosens the skin around its lips. Finally, the snake crawls out of its old skin. A brand new skin takes its place.

SNAKE SENSES

Snakes don’t see or hear as well as other animals. A snake has eyes but no eyelids. They have clear scales over their eyes. Most snakes can see movement, but some snakes are blind.

Snakes do not have ears. They have bones in their heads that can sense low sounds and vibrations.

Snakes have a great sense of smell. A snake flicks out its forked (divided) tongue to collect scents. It doesn’t mean the snake is hungry. The snake pulls its tongue in and sticks the forked tips into a place in the roof of its mouth called Jacobson’s organ. This way of smelling lets snakes find other snakes as well as prey (animals it hunts for food).

Pit vipers, boas, and pythons have small pits on their heads that can sense heat. These pits help a snake sense when a warm-blooded animal is near.

POISONOUS SNAKES

Most snakes will not harm people. Garter snakes and ribbon snakes are harmless snakes. But some snakes can be deadly. They inject a poison called venom when they bite. They use venom to defend themselves or to kill prey.

Poisonous snakes have two big, hollow teeth called fangs. When they bite, the venom comes down through these fangs. Pit vipers keep their fangs folded in their mouths until they are ready to strike. Rattlesnakes are a well-known kind of pit viper. Cobras and coral snakes are also very poisonous.

Spitting cobras do not have fangs. Instead, they spit poison to defend themselves. They aim their venom at the eyes. The venom can cause blindness.

Someone bitten by a poisonous snake should get medical help immediately. Snake venom can be deadly.

BOAS AND PYTHONS

Boas and pythons are kinds of snakes known as constrictors. These snakes have thick bodies and strong muscles. Instead of biting, they wrap themselves around their prey and squeeze. They squeeze so hard that the animal can’t breathe and dies.

HOW DO SNAKES MOVE?

Some snakes move by wiggling and squirming forward. Some snakes make leaping, twisting movements called sidewinding.

Snakes that live in trees coil their tail around a branch. Then they hook their neck into a higher part of the tree and pull the rest of their body up behind them.

WHAT DO SNAKES EAT?

Snakes eat a variety of things: worms, insects, lizards, small mammals, birds, and frogs. Some snakes, such as the Australian bandy-bandy, feed only on other snakes. Other snakes like to eat the eggs of other animals. An adult reticulated python eats larger prey, such as wild pigs, monkeys, and small deer.

Snakes don’t chew their food. They swallow it whole. Their teeth point backward, which helps to keep prey from escaping. Many snakes begin to swallow their prey while it’s still alive. Others kill the animals before eating them.

LIFE CYCLE OF A SNAKE

Most snakes lay eggs. Some sea snakes and snakes that live in cold places give birth to live baby snakes.

Some snakes can begin reproducing at two years of age. Others take slightly longer to mature. Snakes may live for as long as 20 to 30 years.

SNAKES AND PEOPLE

People in Asia and other places kill snakes for meat. Some people make shoes, belts, purses, and other things out of snakeskin. When people build houses and farms, the places where snakes live are often destroyed.

Scientists and other experts fear that some snakes could become endangered if the killing of snakes or the destruction of their habitat (living places) continues. Some countries have laws against killing or selling snakes for their skins or their meat.
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Spiders

“If you want to live and thrive, let a spider run alive!” That is an old English saying that means not killing spiders will bring you good luck. There is also a myth that killing a spider will bring bad weather.

Letting a spider live won’t bring you good luck or good weather. But scientists say there is no good reason to kill a spider. Most spiders will not harm you. They rarely bite. Only 30 of the 40,000 species (kinds) of spiders cause illness when they bite people. The black widow and the brown recluse are two spiders that have painful or deadly bites.

Spiders are important to the balance of nature. Spiders eat mosquitoes and other insects. Spiders help keep insects under control.

ARE SPIDERS INSECTS?

Spiders are arachnids. They are not insects. Daddy longlegs, mites, ticks, and scorpions are also arachnids.

You can tell spiders and insects apart. Spiders have eight legs. Insects have six legs.

The bodies of spiders have two parts. The head and thorax (chest) form one part, and the abdomen is the second part. The two parts are linked by a thin stalk called the pedicel. The bodies of insects, on the other hand, have three parts. A spider’s body has a hard outer shell.

Insects have antennae, and most of them have four wings. Spiders do not have any wings or antennae.

HOW BIG ARE SPIDERS?

The biggest spiders are tarantulas. They have bodies that are more than 4 inches (10 centimeters) long. A tarantula’s legs spread out over 8 inches (20 centimeters). The smallest spiders have bodies that are less than 0.04 inch (1 millimeter) long.

HOW DO SPIDERS MAKE WEBS?

Spiders spin webs out of silk threads. The silk comes from glands in the spider’s abdomen.

The glands make a liquid. The liquid goes out through tubes as thin as a hair. The tubes are called spigots. The spigots go to spinnerets on the spider’s abdomen. Dozens of spigots go to each spinneret. The spinnerets are like fingers. They can move to stick silk threads to a wall or wrap prey (animals they eat) in silk.

WHY DO SPIDERS MAKE WEBS?

House spiders, garden spiders, and other spiders spin webs to catch prey. Some webs are shaped like funnels. Some webs are flat. Some webs are like a circle. The spiders feel the web vibrate when a fly or other insect gets trapped in the web’s sticky threads.

Not all spiders spin webs, but all spiders make silk threads. Spiders leave a silk thread behind them as they go. They can use this thread to make a quick escape. Spiders use their silk to make nests.

Some spiders use their silk to wrap up captured prey. All spiders are carnivorous (meat eaters). They eat insects and sometimes other spiders.

Scientists divide spiders into two groups called web spiders and ground spiders. Ground spiders hunt their prey. Wolf spiders and other ground spiders have long, thick legs. They wait for an insect to come along and then jump on it.

HOW DO SPIDERS EAT?

A spider has special mouthparts called chelicerae. There is a sharp fang at the end of each chelicera. The fang is hollow. The spider stabs its prey with the fang. Poison from a poison gland in the spider’s body goes through the fang and into the prey. Big tarantulas are powerful enough to kill frogs and lizards. Small jumping spiders that live in the tropics can jump a long way to attack prey.

Spiders cannot chew their food. The spider spits juices into the wound made by its fang. The juices start to digest (break down) the prey outside the spider’s body. The spider’s stomach has muscles that are powerful enough to suck in the digested prey.

A spider can use its mouthparts for things other than eating. It can use them to carry prey. Ground spiders use their mouthparts to dig tunnels in the soil.

DO SPIDERS HAVE HAIR?

Some spiders have hair on their bodies. All spiders have hairs on their legs. Spiders use their hairs to feel and smell things. Each leg has seven parts with joints between them.

The hairs of many tarantulas have barbs like tiny fishhooks. Tarantulas can brush off their abdominal hairs when they feel threatened. The barbed hairs fly through the air. They cause a burning feeling if they get in your skin or up your nose.

HOW DO YOUNG SPIDERS GROW?

The male spider fertilizes eggs from a female spider. The female makes a silky cocoon for her eggs.

Some spider mothers hide their cocoons and then leave them. Other spiders guard their cocoons until the eggs hatch. Female wolf spiders carry their cocoons on their bodies until the eggs hatch.

Spider eggs hatch inside the cocoon. The young spiders go through different life stages. The first stage is as a white, wormlike larva. After about two weeks, the larva changes into a spiderling. Spiderlings look like grown-up spiders, only smaller.

Spiderlings lose their hard outer shell a number of times as they grow. A new shell takes the place of the old one. This is called molting. Small spider species may molt about 5 times. Some large tarantulas may molt as many as 40 times. The last time a spiderling molts it becomes a grown-up spider.
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Panda - Da Xiong Mao

(MS. Encarta) - Giant Panda, bamboo-eating bear that lives in forests high in the mountains of central China. As one of the rarest but most recognized animals in the world, the giant panda has become an international emblem of endangered species and wildlife conservation efforts. The Chinese name for the giant panda, da xiong mao, means “great bear-cat.”

Physical Description

he giant panda resembles other bears in general appearance, with the exception of its coloring. The giant panda is white with black patches over its eyes, ears, and legs and a black band across its shoulders. Like other bears, the giant panda has long, shaggy fur. It keeps the giant panda warm in the cold and damp forest.

Giant pandas have an enlarged wrist bone on the forefoot that functions as an opposable thumb. Their premolar teeth and molars are generally larger and broader than those of other bears, and their jaw bones and cheek muscles are exceptionally strong. These adaptations assist giant pandas in holding, crushing, and eating bamboo.

An adult giant panda usually weighs between 75 and 160 kg (between 165 and 350 lb). Males are generally 20 percent heavier than females. The giant panda grows to about 1.5 m (about 5 ft) in head-and-body length, plus a 12.5-cm (5-in) tail.

Habitat and Behavior

Giant pandas are found in the wild in the Sichuan, Gansu, and Shaanxi provinces of central China. They live in a few rugged mountain ranges at the eastern edge of the Tibetan Plateau where temperate broadleaf and coniferous forests contain dense stands of bamboo. Giant pandas are usually found at elevations between 2,300 and 3,800 m (7,500 and 12,500 ft) but will relocate to lower elevations in winter and spring. However, the zone of bamboo vegetation below 1,200 m (3,800 ft) has been cleared for agriculture in many areas, greatly restricting the giant panda’s range.

Unlike other bears that live in temperate climates, giant pandas do not hibernate. Bamboo is usually abundant and green even in winter, so they generally have no lack of food.

Although giant pandas eat bamboo, they have the digestive system of a carnivore like other bears. Their system cannot efficiently digest bamboo, so they must eat large amounts to obtain enough nutrition. A giant panda must consume between 12 and 38 kg (26 and 84 lb) of bamboo each day. It spends 10 to 16 hours a day foraging and eating. A giant panda usually feeds in a sitting position, enabling it to grasp a bamboo stalk between its “thumb” and first two digits. It strips away the bamboo’s tough outer layer with its teeth, and then slowly eats the peeled stalk. It also eats bamboo leaves, shoots, and roots. If its usual food supply is unavailable, a giant panda may feed on other plants, such as irises and crocuses, or even small animals, such as rodents.

When not eating, a giant panda spends most of its time sleeping and resting. Giant pandas seem to have no permanent den, although they find shelter and give birth in caves or hollow trees.

Giant pandas are fairly solitary most of the year. Small groups of giant pandas share a large territory and sometimes meet outside the breeding season. Both males and females may have overlapping ranges, and males show no evidence of territorial behavior other than scent-marking their routes. Giant pandas make a variety of sounds to communicate with each other, including bleats, honks, barks, growls, moans, and squeals. However, they never roar like some other bears.

Mating takes place from March to May, and the young are born during August or September. A newborn cub usually weighs only 90 to 130 g (3 to 5 oz) and is about the size of a stick of butter. Born nearly hairless and unable to open its eyes for 40 to 60 days, the cub is completely defenseless and dependent on its mother. A giant panda mother will cradle her tiny cub in one paw and hold it close to her chest, nursing it often. Nearly half of giant panda pregnancies produce twins, but only one cub usually survives in the wild because the mother will neglect the other one. In captive breeding centers, human caretakers will switch the cubs so each receives enough milk from the mother to survive.

A giant panda cub begins to walk when it is three to four months old. It starts eating bamboo around the fifth month of its life but will not be fully weaned from its mother’s milk until the eighth or ninth month. Giant panda cubs may stay with their mothers for up to three years before striking out on their own.

In the wild, a female giant panda will usually have a cub every other year for about 15 years of her life. However, many panda cubs do not survive to adulthood, and losses of young hinder the recovery of giant panda populations. Giant pandas generally live to between 20 and 35 years of age in captivity, and it is believed their lifespan is longer in the wild.
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Tigers

(MS.Encarta) - They can move silently through the forest. They can kill a huge wild boar with a single bite. Their roar sends shivers down your spine. They are perhaps the perfect killing machines. They are tigers.

TIGERS ARE HUGE CATS

Tigers are members of the cat family. Lions, leopards, cheetahs, and house cats are also members of the cat family. Tigers are the largest cats, and the only cats with stripes. They live in large forests in southern and southeastern Asia.

A tiger’s short fur is usually colored dark orange with black stripes. Each tiger has different stripes, and you can use them to tell tigers apart. The stripes make a tiger stand out if you see them in the open. In the forests where tigers live, however, the stripes make them almost invisible.

Like house cats, tigers have soft pads on the bottoms of their paws. These pads allow tigers to move silently through the forest. Tigers have long, sharp claws at the ends of their feet. They pull the claws in until they need them. When needed, the claws pop out like knives.

Their big, yellow eyes give tigers sharp sight to help find prey. Tigers see as well as people during the day, and much better than people at night. They also hear very well. They can turn their ears toward sounds.

Tigers have explosive speed. They have strong muscles and long legs that help them move extremely fast over short distances. Their long tails give them balance while running fast. Powerful jaws and sharp teeth help tigers grab and kill prey once they catch it.

Some tigers in zoos and circuses are white with blue eyes. People bred these tigers because white tigers fetch more money from tourists. In the wild, white tigers are very rare. Zoos no longer breed tigers to be white.

WHAT DO TIGERS EAT?

Tigers eat the largest animals they can catch. They hunt wild boars, deer, wild cows, young elephants, and young rhinos. Tigers also kill farmers’ cows and goats. Tigers prefer to avoid people. Sometimes they attack and kill people, but only if they can’t find other food.

HOW DO TIGERS HUNT?

Tigers hunt alone. They usually hunt at night. Tigers will travel 6 to 20 miles (10 to 30 kilometers) in one night while searching for prey.

Tigers sneak up on their prey. They use the trees and grass to hide. A tiger slowly and silently sneaks until its prey is about 30 feet (about 10 meters) away. The tiger then lunges, lightning-fast, and grabs the animal in its paws and wrestles it to the ground. It sinks its teeth into the animal’s neck to kill it.

The tiger then drags the dead animal to a hiding place. The tiger will eat for two or three days until the meat is gone. On average, a tiger must kill once every eight days to avoid starving. Even though tigers are built to hunt, they are only successful in 1 out of 10 or 20 hunts!

WHY DO TIGERS ROAR?

Tigers roar to scare other tigers away. A tiger’s roar tells other tigers to keep out of its hunting ground. Tigers also use smells and scratch marks to mark their territory.

FEW TIGERS REMAIN

Tigers are disappearing in the wild. There are less than 7,000 tigers still alive. People pose the biggest threat to tigers. People destroy the tiger’s forest home. People have taken away tigers’ food.

People also hunt tigers for sport and sell their skins and bones. Most countries have passed laws against hunting tigers, but poachers continue to kill them.

A tiger in a zoo can live to be 20 years old. A wild tiger will likely not live to be 15. Only half of the tiger cubs born live long enough to leave their mother. Adult tigers have violent fights with each other. Other animals injure and kill tigers. They can also starve to death when there is no food.

SAVING TIGERS

Many nations have passed laws to protect tigers. Scientists are trying to create more national parks for tigers to roam in and make the forests they live in bigger. Zoos also breed many tigers.
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Turtles and Tortoises

(MS.Encarta) - Turtles were crawling and swimming around when gigantic dinosaurs walked Earth. The first turtles lived about 185 million years ago. The dinosaurs died out, but turtles lived on. Many kinds of turtles still thrive today.

Tortoises are a kind of turtle that lives all its life on land. Other turtles live at least part of the time in water.

WHY DO TURTLES HAVE SHELLS?

A turtle is the only reptile with a shell. The shell is made of a bony or a leathery material. A shell is like a suit of armor. Most turtles can protect themselves by pulling their heads, necks, and legs into the shell.

The top part of the shell is called the carapace. This part covers a turtle’s back. The bottom part is called the plastron.

Most turtle shells are brown, black, or olive green. Some turtles have red, orange, yellow, or gray spots or lines on their shells. The painted turtle is very colorful. It has a yellow plastron and a black or olive carapace with red markings around its rim.

Tortoises have big, heavy shells to protect them from enemies on land. Sea turtles have light shells so they can swim more easily.

WHAT’S A TURTLE SHELL MADE OF?

Most turtles have shells that are covered with horny scales called scutes. The scutes are made from skin tissue. They overlap and make the shell hard and strong. Some turtles do not have scutes. Instead they have soft shells covered with tough skin.

The inner part of a turtle’s shell is made up of many bones. These bones include part of a turtle’s backbone and its ribs. The backbone and ribs are attached right to the shell. This is why a turtle cannot crawl out of its shell.

DIFFERENT KINDS OF TURTLES

There are about 270 species (kinds) of turtles alive today. Scientists group turtles by how they pull their heads into their shells.

Some turtles fold their necks sideways under the top of their shell. They are called side-necked turtles. Hidden-necked turtles bend their heads directly back into the shell. Sea turtles cannot pull their heads into their shells at all. But they are grouped with hidden-necked turtles.

Turtles come in all sizes. The largest turtle is the leatherback sea turtle. Its shell can be 8 feet (2.4 meters) long, and it can weigh over 2,000 pounds (900 kilograms). Other sea turtles, such as the green turtle and the loggerhead turtle, are also very large.

The largest land turtles are the giant tortoises that live on the Galápagos and Aldabra islands. They can measure 4 feet (1.2 meters) long and weigh as much as 600 pounds (270 kilograms).

Among the smallest turtles are the American mud turtles and musk turtles. Many mud and musk turtles have shells that are less than 5 inches (13 centimeters) long. The shell of the tiny speckled cape tortoise of South Africa is only 4 inches (10 centimeters) long.

A TURTLE’S BODY

The kind of limbs a turtle has depends on where it lives. Turtles that live on land have thick legs for walking. Turtles that live in water have long webbed toes for swimming. Sea turtles have flippers to paddle through the water.

All turtles have tails. Most turtles have short tails. American snapping turtles have long tails. The Asian big-headed turtle has a large, strong tail covered with scales.

Turtles, like other reptiles, breathe air through lungs. Even sea turtles must come to the surface to breathe. Some turtles can hold their breath for months at a time. They do this when they hibernate at the bottom of a pond or river during winter.

WHERE TURTLES LIVE

Turtles are cold-blooded animals. This means they cannot produce their own body heat. If it is cold outside, the turtle will be cold. If it is warm, the turtle will be warm. For this reason, turtles cannot live in very cold places, such as Antarctica. But they can live in most other places.

Side-necked turtles live in South America, Africa, and Australia. Hidden-necked turtles live in North America, Europe, and Asia. Turtles live in ponds and rivers. They live in forests and grasslands. Some turtles even live in deserts. Sea turtles live in the ocean.

WHAT TURTLES EAT

Some turtles only eat animals, such as insects, worms, and small fish. Some turtles only eat plants. Most turtles eat both animals and plants.

Turtles do not have teeth. They have a beak, similar to a bird’s, with ridges that they use to cut food. Turtles that eat animals have knife-sharp ridges for slicing through their prey. Plant-eating turtles have ridges with sawlike edges that help them cut through tough plants. Turtles have a tongue that helps them swallow food.

HOW TURTLES REPRODUCE

After mating, female turtles lay from 1 to 200 eggs on land. They dig a nest to keep the eggs safe. The baby turtles must take care of themselves as soon as they hatch from the eggs. Turtles that survive can live a long life. Some turtles can live more than 60 years. Some tortoises live to a very old age—up to 150 years!

THREATS TO TURTLES

Animals such as raccoons, snakes, and skunks love to eat turtle eggs and baby turtles. Many birds eat baby turtles as they crawl toward the sea. Fish eat baby turtles once they enter the water. Most turtles never live to grow up.

People are the biggest threat to turtles. People hunt turtles for their meat, eggs, and shells. They destroy places where turtles live by building farms and towns. They pollute the water where turtles swim. Sea turtles get trapped in fishing nets. Some species of turtles have become endangered. Many states and countries have passed laws to protect endangered turtles.
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Whales

(MS.Encarta) - What is the biggest animal on Earth? Hint: It’s not an animal that lives on land. It’s the blue whale. Blue whales can grow to be 80 feet (24 meters) long and weigh 150 metric tons. The heart of a blue whale is as large as a small car!

WHALES ARE NOT FISH

The body of a blue whale looks a lot like the body of a fish. All whales look like fish, but whales are not fish. Whales are mammals that live in water.

There are many differences between fish and whales. Whales are much bigger than fish. Fish stay underwater all the time and breathe through gills that take oxygen out of water.

Whales breathe through lungs just as you do, so they must come up for air. Fish are cold-blooded, which means their body is the same temperature as the water around them. Whales are warm-blooded (like humans), and so their bodies always stay warm. Fish lay eggs. Whales, like almost all mammals, give birth to live young and feed their babies on mother’s milk.

Fish and whales both have tail fins. The tail fins of a fish are vertical (up and down). A fish swims by moving its tail from side to side. The tail fins, or flukes, of a whale are horizontal (side to side). A whale swims by waving its tail up and down. Whales also have two front limbs called flippers that they use to steer.

DIFFERENT KINDS OF WHALES

There are more than 75 species (major kinds) of whales. Zoologists (scientists who study animals) divide whales into two groups by the way they eat. One group, the toothed whales, have sharp, pointy teeth for catching fish, squid, and other prey. Sperm whales, beaked whales, narwhals, belugas, dolphins, and porpoises are toothed whales.

The other group, the baleen whales, do not have teeth. Instead, they have big plates with brushes on the edge called baleen, or whalebone. Baleen whales take in a big mouthful of water. The baleen then traps small fish and plankton (tiny plants and animals that float in the ocean). Rorquals, gray whales, blue whales, and right whales are some of the baleen whales.

BLUBBER AND BLOWHOLES

A whale has smooth skin that can be black, white, or other colors. Under their skin, whales have a thick layer of fat, called blubber. Blubber stores energy and helps keep the whale warm in cold water.

Whales don’t have noses. They breathe in and out through blowholes on the top of their heads. Toothed whales have one blowhole. Baleen whales have two blowholes. Whales can hold their breath underwater for a long time. Baleen whales can stay underwater about an hour. The sperm whale can stay underwater for even longer—about 80 minutes.

When a whale comes to the surface, it blows air out through its blowhole. The warm air looks like a mist. The mist is called the spout.

SEEING AND HEARING UNDERWATER

Whales have excellent eyesight. Oily tears help keep their eyes safe and clear underwater.

Whales have good hearing. Toothed whales use sound to hunt for food in the deep, dark ocean. They send out a sound that bounces back when it hits a fish or other animal. The echo tells the whale where the animal is.

Baleen whales do not have a good sense of smell. Toothed whales can’t smell at all.

COMING OUT OF THE WATER

Whales never climb up on land. But some whales can jump right out of the water. They land on their backs with a loud smack. Scientists call this behavior breaching. Scientists don’t know why whales breach. Are they trying to attract a mate? Are they “talking” to other whales far away? Or do they just want to get a good look at what is around them?

MIGRATING WHALES

Some whales migrate (move from place to place). These whales swim great distances every year. Baleen whales travel to cool waters near the Arctic or Antarctica every summer. They feed on krill, small animals that look like shrimp. In the winter, baleen whales head for warmer waters near the equator to breed.

Other whales do not migrate. Narwhals, for instance, live year-round in the cool waters of the Arctic and North Atlantic oceans.

HAVING BABY WHALES

After male and female whales mate, it takes from 10 to 16 months for a baby whale to form. The length of time depends on the whale species. A whale gives birth to only one baby at a time. The baby whale nurses on the mother’s milk for as long as a year.

Some whales can mate and have babies at 7 years of age. Other whales take longer to mature, and first mate as late as age 14.

LIFESPAN OF A WHALE

Small whales live about 20 years. Large whales can live to be 60 years old.

ANIMALS THAT HUNT WHALES

Some large sharks, such as the great white, can eat whales. But people are the main whale hunters. People began to hunt large numbers of whales in the 1700s. They hunted the sperm whale for a waxy liquid used to make candles and for whale oil to burn in lamps. People hunted baleen whales for whalebone to make combs and other products.

People no longer hunt whales for lamp oil or whalebone. However, they still hunt whales for oils and other materials used to make soap and cosmetics. Many whales, including right, bowhead, gray, and blue whales, have become endangered. Some countries in the mid-1900s decided to limit or forbid whale hunting. A few nations kept on hunting whales. Conservation groups now ask that all whale hunting be stopped. They fear that some kinds of whales could disappear forever.
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Zebras

(MS.Encarta) - If you saw a horse with black-and-white stripes, you might think you were “seeing things.” But you would be seeing a zebra. Zebras are a kind of horse. They walk, trot, canter, and gallop just as horses do. Zebras live only in Africa.

There are three species (kinds) of zebras: Grévy’s zebra, the mountain zebra, and the plains zebra (also known as Burchell’s zebra). Each kind of zebra has its own pattern of stripes. And you can tell individual zebras apart. No two zebras have exactly the same stripes.

WHY DO ZEBRAS HAVE STRIPES?

Some scientists think zebra stripes act as protection. Zebras like to hang out together in groups. When zebras are feeding together, the stripes can confuse an attacking animal. The stripes make it hard for a lion or hyena to pick out one zebra in the crowd. The stripes also break up the zebra’s outline and make zebras hard to see at a distance.

Other scientists think zebras can tell each other apart by their stripes. The stripes might help zebras find family members and friends.

Each species of zebra has a different pattern of stripes. The Grévy’s zebra has narrow stripes set closely together. The mountain zebra has wider stripes. The plains zebra has the widest stripes of all. The plains zebra also has stripes that wrap around from its back to its belly. The other two kinds of zebras have white bellies. The plains zebra sometimes has faint gray stripes between the black stripes on its sides.

THE BODY OF A ZEBRA

Zebras are usually smaller than horses. The mountain zebra is the smallest zebra. These zebras are about 4 feet (about 1.2 meters) high at the shoulders. Plains zebras are slightly larger. Grévy’s zebra is the largest zebra. It stands about 5 feet (about 1.5 meters) high at the shoulder.

Zebras have manes that stick straight up from their necks. A zebra’s tail is shorter than a horse’s tail.

Zebras can hear very well. They turn their ears and big eyes toward the source of any sound. They are always on the lookout for danger. How zebras hold their ears helps to show what mood they are in. A zebra that flicks its ears back and forth is upset.

Zebras do not have a very good sense of smell. However, they can smell smoke. Smoke might mean the grassland where they live is on fire.

WHAT DO ZEBRAS EAT?

Like other members of the horse family, zebras are grazing animals. They feed on coarse grass. Zebras have chisel-shaped teeth at the front of the mouth to bite off the grass and large molars (back teeth) for grinding up food.

Zebras spend over half their time eating. In a single day, a herd of zebras may wander more than 12 miles (20 kilometers) in search of food. While some zebras have their heads down munching on grass, others are on the lookout for danger. Some zebras also stand lookout while other zebras lie down and sleep.

FAMILY LIFE OF ZEBRAS

Zebras form small family units. A zebra female, or mare, is pregnant for about 12 months. She usually gives birth to one foal at a time. The newborn foal feeds on its mother’s milk for up to a year.

The family units of the plains and mountain zebra are very stable. An adult male, or stallion, heads the family. A family can have up to six adult females or mares. The mares often remain in the group for life. The stallion helps protect all the mares and foals in the family unit. Sometimes a younger male may drive out the stallion.

When the animals are on the move, the oldest mare is first in line, followed by her foals. The other mares and foals line up behind by age. The stallion brings up the rear.

A family unit of Grévy’s zebras is usually made up of a nursing mare and one or two of her foals. Stallions help look after their own foals. Adults do get together in groups, but each mare comes and goes as she pleases.

All zebras like physical contact. They groom each other by nibbling on each other’s fur. They flick their tails to keep flies away from each other’s faces.

THREATS TO ZEBRAS

The main natural enemies of zebras are lions, hyenas, and other wild animals. However, people are a greater threat to zebras. People hunt zebras. They hunted a kind of zebra called the quagga until the animal died out.

Today, Grévy’s zebra and the mountain zebra are endangered. People still hunt them for meat and hides. People turn the lands where zebras live into farms and ranches. This leaves fewer places for zebras to live.
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The Zoo

(MS. Ancarta) - You don’t have to go to Africa to see an elephant. You don’t have to go to the North Pole to see a polar bear. You can see elephants, bears, lions, crocodiles, hawks, and all kinds of other wild animals at a zoo.

Zoos are places where animals are kept so that you can learn about them. Zoos are also places where scientists study animals. Some zoos help preserve endangered animals.

WHAT DOES A ZOO LOOK LIKE?

Zoos once kept animals in cages. Today, they try to keep animals in larger, open places. The places look like the home of each animal that lives there. They have rocks and trees, bushes, and other plants that the animal likes. Some places might look like deserts or prairies or rain forests. Polar bears have ponds of ice-cold water to play in. Monkeys have trees they can climb. Pandas have lots of bamboo to eat.

The places where the animals live have fences and other borders. But the fences are hidden and hard to see. Part of the San Diego Wild Animal Park in California looks like a plain in Africa. It seems like the animals are free to go anywhere.

Many zoos have places with closed-in tops where hundreds of birds can fly around. Some zoos have places you can walk through to see butterflies sipping nectar (juice) from flowers.

WHO WORKS AT A ZOO?

A zoo needs many people to care for the animals. Zoologists are scientists who study animals. They learn about how the animals live. They learn what makes the animals happy.

Veterinarians are animal doctors. They take care of any sick zoo animals. They try to keep all the animals healthy.

Zookeepers take care of everything the animals need. They make sure the animals have plenty of food and water. They watch for any problems with the animals.

Zoos have other workers, too. They have guides who give tours and talk about the animals. They have cooks who work in zoo kitchens to make food for the animals. They even have people who build the homes for zoo animals to live in.

WHERE DO ZOOS GET ANIMALS?

In the past, most animals in zoos were captured wild animals. Today, zoos want their animals to breed (mate and have babies).

It is easy to get some animals to breed at a zoo. Lions living at zoos have many cubs. It is hard to get other animals to breed at a zoo. Cheetahs and giant pandas rarely have babies when they live in a zoo.

PROTECTING ENDANGERED ANIMALS

Zoologists try to save some endangered animals by breeding them at a zoo. Sometimes, they put animals born in a zoo back into the wild. They put the endangered Père David’s deer into an animal preserve in China. They put red wolves in places in North Carolina and Tennessee. These zoo-born animals now live completely in the wild.
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Kangaroo

(MS.Ancarta) - Kangaroo, common name for a group of mammals found in Australia and neighboring islands. Kangaroos are marsupials, a type of mammal that gives birth to undeveloped young. In kangaroos and many other marsupials, the young are carried and nurtured in a special pouch on the mother's body.

More than 50 different kinds of animals are grouped together in two kangaroo families. The large kangaroos include red kangaroos and gray kangaroos, wallabies, pademelons, and quokka; they belong in the family Macropodidae.

The other family, Potoroidae, is made up of assorted smaller species, such as various rat-kangaroos, bettongs, and potoroos.

The largest kangaroos are the gray kangaroo and red kangaroo, which can stand up to 2 m (6.5 ft) tall and weigh up to 85 kg (187 lb). The smallest are the musky rat-kangaroos, ratlike animals measuring about 30 cm (12 in), not including the tail.

Kangaroos are found only in mainland Australia and New Guinea and on some of their offshore islands, such as Tasmania. A few species have been introduced to other countries, such as tammars in New Zealand and a rock wallaby in Hawaii. Kangaroos inhabit every imaginable type of habitat throughout Australia and New Guinea. Red kangaroos and gray kangaroos are found in grasslands, savannas, and open woodlands. Rock wallabies live on nearly vertical rock walls in the southern desert. Bettongs inhabit burrows in arid scrubland. As their name implies, tree kangaroos are found high in the rain forest canopy, while rat-kangaroos scamper nimbly through the dense, wet understory below. Red-necked wallabies live in many habitats, including the frigid peaks of Tasmania's mountains, and the endangered quokka's last refuge is just two windblown islands off the southwestern Australia coast. Several species of kangaroos are so adaptable that they are common inhabitants of public parkland, suburban gardens, and even golf courses.

Fossil evidence shows that the first kangaroos appeared in Australia about 15 million years ago, during the Miocene Epoch. As a result of climate changes about 8 million years ago, Australia's rain forests gave way to open woodlands and savanna, and kangaroos evolved into many of the forms we know today. The now extinct giant kangaroos stood up to 3 m (10 ft) high and weighed 200 kg (440 lb).

Physical Characteristics

Most kangaroo species have large ears and relatively small heads. Their small front feet have five digits of unequal length, while the back feet typically have four digits. One of the toes on each hind foot has a sharp claw used in defense. Many species are drably colored to closely match their surroundings, helping them to hide from predators. Males of the larger kangaroo species are noticeably bigger in size than the females, a trait known as sexual dimorphism.A physical feature that distinguishes kangaroos from other marsu pials is the adaptation of the hind legs and tail for hopping. In red kangaroos, for example, the hind legs are very large—roughly ten times the size of the small front limbs. When moving slowly, kangaroos use all four legs. When they need to move fast, they rise up on their muscular hind legs and start hopping.

The leaps of some kangaroos are legendary. Red kangaroos moving at top speeds can cover 5 m (16 ft) or more in a single bound. They are able to reach speeds of more than 50 km/h (31 mph) for short periods. The kangaroo's heavy, muscular tail is also important for locomotion. It serves as a counterbalance and a rudder during hopping, and provides support when the animal sits.

The only member of the kangaroo family that does not hop is the musky rat-kangaroo. Scientists have tried to learn why hopping is so widespread among kangaroos but is so rare in other mammals. Studies have shown that hopping is energy efficient for kangaroos, partly because of springlike tendons in their legs. The energy required to start hopping is quite high, but very little extra energy is needed to hop faster and faster. In contrast, mammals that run on all fours require increasing amounts of energy as speed increases.
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