Category Plants & Animals

Why Are They Gone?

Just as you change while you grow, the world and the things that live on it change, too. Most scientists believe that the earth has changed many times in the past, and that many kinds of animals have lived on our planet.

Once, there were scaly reptiles as big as houses. Once there were horses no bigger than cats. And, very long ago, no animals of any kind lived on land. All the animals lived in the ocean.

Dinosaurs were very important animals. They ruled the earth for more than 100 million years. They wallowed in great swamps and prowled through hot, damp forests.

Then something happened, and all the dinosaurs died. We don’t know why dinosaurs became extinct.

Some scientists think dinosaurs became extinct slowly. Swamps began drying up. New plants were taking the place of old ones. Perhaps dinosaurs could not live with these changes. Other scientists think Earth was struck by a huge asteroid. The air then filled with dust that blocked out the sun’s rays. Eventually, this changed the climate and led to the death of the dinosaurs.

Perhaps all these things, and others that we don’t know about, caused the dinosaurs to die out. It’s a great mystery.

Picture Credit : Google

Animals in Danger 
Hundreds of years ago, thousands of birds called dodos lived on the earth. But people overhunted them for food and introduced new animal enemies to their habitats. Now there are no dodos. Today, the numbers of polar bears, rhinoceroses, tigers, and many other animals are going down. These animals are in danger. Why? 
• Their homes are being destroyed. 
• People hunt them for their fur, horns, skins, and meat. Some are hunted for sale as pets and some because people think they are pests. 
• Pollution kills them. 
• Growing numbers of people crowd out animals and use up all the land and food. 
• People introduce new animals to a habitat, upsetting the balance of nature. 
Unless people work hard to save them, many other animals will become extinct like the dodo. 

Picture Credit : Google

Food Chain

A field of green grass waves in the wind. A furry rabbit hops by and nibbles the grass. As the rabbit scurries around, an owl perches overhead. The owl swoops down, grabs the rabbit, and flies away to eat it. When it has eaten its fill, the owl leaves part of the rabbit’s body in another field of grass. The rabbit’s body feeds the soil.

It may seem cruel that animals kill and eat one another. But this is just one way in which wild creatures help each other and keep nature in balance. The grass, the rabbit and the owl are part of an important system in nature called a food chain.

All food chains begin with sunlight. Sunlight provides food for plants. Plants are the primary producers in a food chain. They use sunlight, water, and air to produce food to live and grow.

Animals that eat plants are another link in the food chain. They are consumers. Animals that eat the plant-eating animals are also consumers. The rabbit and the owl are consumers.

Tiny living things called decomposers are also part of the food chain. They break down dead plants and animals into parts. These parts nourish the soil in which the plants grow.

Picture Credit : Google

Animals on the Move

When the cold days of winter come, many animals find it hard to find food. So they fly, march, scamper, or swim to warmer places. When spring comes, they fly, march, scamper, and swim back. This movement from place to place as the seasons change is called migration.

Barn swallows, monarch butterflies, ladybirds, caribou, whales, salmon, and lemmings are just a few of the animals that migrate.

When birds migrate, they often fly great distances. Sometimes they cross oceans and continents. In spring, they migrate back. Sometimes they return to the same nests they used the summer before.

In winter, caribou leave their summer home in northern North America and begin dangerous journey southwards in large herds. The following spring they journey northwards again.

Lemmings are small mammals that live in northern Europe. They migrate sometimes, too. When there is a lot of food, lemmings have many young. When the food runs out, they migrate. Sometimes they travel along roads and through towns looking for food.

Picture Credit : Google

Sleeping Through Winter

Every autumn, a woodchuck eats large amounts of food, curls up into a ball, and goes to sleep in its underground home. But the woodchuck’s sleep isn’t like your sleep. The woodchuck’s heart and breathing slow down and nearly stop. Its body changes. Most of the time, the woodchuck’s body is warm because it is a warm-blooded animal. But the woodchuck’s body grows cold before it goes into its long winter sleep. As it sleeps, its body lives off the energy from the extra food it ate in autumn.

The woodchuck’s sleep is called hibernation. Ground squirrels, bats, hamsters, hedgehogs, and other warm-blooded animals also hibernate.

Snakes, turtles, frogs, and toads hibernate in a different way. A snake is cold-blooded. Its body is just as warm or as cold as the air around it. So when the weather grows colder, a snake’s body grows colder. The snake tries to get warm by crawling into a hole. But as the weather becomes colder, the snake’s body becomes cold and stiff. Its heart and breathing nearly stop.

When spring comes, the woodchucks and other warm-blooded animals wake up. The snakes warm up, too, and crawl out of their holes. The world is alive again!

Picture Credit : Google

Animal Partners

Hungry crocodiles usually try to eat birds that come near them. But one kind of bird can walk among crocodiles safely. In fact, this bird can lay its eggs in crocodile nests!

A bird called the water dikkop eats insects that disturb crocodiles. The bird gets an easy meal and the crocodile becomes more comfortable. So the birds are really helping the crocodiles. Maybe that’s why the crocodiles don’t harm them.

Little fish called wrasses help many other bigger fish. Tiny worms often fasten themselves to a fish and make sores on its body. When this happens, the fish goes to a coral reef where a wrasse lives. The little wrasse hunts all over the fish’s body and eats the worms.

A European fish called a bitterling teams up with certain freshwater clams. The female bitterling lays her eggs in the clam. When the baby fish leave the shell, clam larvae are buried in their skin. After the clam larvae have grown a bit, they leave the fish and sink to the bottom of the pond or river. The clam provides a safe place for the fish to lay its eggs, and the fish helps spread baby clams along the pond bottom.

The water dikkop, the wrasse, and the bitterling all get something from the animals they help. Some get food as a reward for getting rid of annoying pests. Others help each other reproduce.

Warning!

Have you ever wondered what animals is “saying” when they tweet, squeak, mew, or bark?

Sometimes, animals make sounds to find a mate. But other sounds are calls for help or cries of danger. A dolphin that is hurt makes a high whistling noise to get the attention of other dolphins. The other dolphins use their backs and flippers to keep the injured dolphin near the top of the water so it can breathe.

Some animals “talk” without using any sounds. Deer and many other animals mark their territory by rubbing a special scent on trees or bushes. Glands in the faces of some male deer give off a scent that warns other males to stay away.

Other animals communicate by changing their body positions. Whenever two wolves in the same family meet, they use their bodies to show which wolf has a higher rank, or position. The high-ranking wolf stands straight, holds its tail high, and points its ears forwards. A low-ranking wolf crouches, holds its tail between its legs, and flattens its ears.

Song and Dance

Have you ever seen fireflies flashing on a summer night? If so, you’ve seen male fireflies looking for mates. The male firefly flashes his light to attract a female. Animals use all sorts of things—light, colourful feathers, and even food—to attract mates.

The male satin bowerbird of Australia builds a kind of house out of grass and twigs. It decorates the house with bright stones, flowers, and seeds. When a female comes near, the male spreads its wings and “dances”.

Other animals make “songs” to attract mates. Crickets and grasshoppers make a loud sound by rubbing their wings together, or by scraping a leg against a wing. Many frogs and toads blow up a large sac under their chin. This makes their croaking sound extra loud.

Some animals use “perfume” to attract a mate. Female silkworm moths release sweet-scented chemicals to attract males. For some females, food is a gift of love. A male tern catches a fish and offers it to the female. Male nursery-web spiders present the female with a captured fly before mating.

Safety in Numbers

A herd of baboons hunts for food at the edge of a grassy plain in Africa. Each baboon is looking and listening every second. There might be a lion creeping through the grass towards the herd!

If a baboon saw or heard something, it would give a loud grunt. Baboon grunts sound almost like someone yelling “Hah!” Then all the baboons would hurry to climb trees. Because of one baboon’s warning, all the baboons would be safe.

Some animals live together in herds. They are safer that way. An animal by itself may not see or hear the enemy that creeps towards it. But if there are many animals watching, there are many more chances that one animal will see or smell danger and warn the others.

Herds of baboons, zebras, antelopes, and deer run when they sense danger. But sometimes a whole herd of animals will fight an enemy.

Sometimes the safest place to be is in a herd. There is safety in numbers!