Saturday, November 24, 2007

The nature of microscopic

This single-called creature is called a ciliate because it is covered with tiny hairs known as cilia, which push it through the water.

Euglena moves around by beating a hair-like growth called a flagellum. It lives like a plant, by harnessing energy from sunshine.

Each vorticella consists of a single cell with a cup on a long stalk. Tiny breathing hairs (cilia) drive food particles into the centre of the 'cup', where they are absorbed.

Invisible occupant
This dust mite, a tiny relative of spiders, is magnified around 375 times. It collects food with microscopic picers, and usually feeds at night.

Cyclops are microscopic relatives of crabs and shrimps. They get their name from the fact that they have only one eye, like the Cyclops of Greek legend. The two little bags attached to either side of this animal's tail contain eggs.

Next, continue the microscopic kind
The microscopic world that feeds the whales
Blue whales feed on very small animals called krill, using their huge sieve-like mouth to catch thousands at a time. The krill feed on microscopic animals and plants called plankton that float in the upper layers of the ocean. So blue whales, which are the largest living creatures in the world, are directly dependent on some of the smallest creatures for their food.

After this, find out about kinds of microscopic

Friday, November 23, 2007

What is the smallest living thing?
The smallest living things are viruses. They are like car engines without any wheels or bodywork attached, they have no way of moving around and no cell wall, unlike other living thing. Viruses do not even have any way of reproducing themselves. In order to produce more viruses, they have to invade other cells and take them over. This is why viruses cause diseases. When you catch a cold, the cells in your nose have been taken over by viruses so that they can reproduced themselves.

How to live on leaves
Animal such as deer and horses have bacteria in their digestive systems that allow them to digest grass and leaves. Our ancestors once had these bacteria too, and attached to your intestine is an 'appendix'. This empty pocket is all that remains of the large structure which aonce held leaf-digesting bacteria.
What tiny creatures share your home?
If you think your house just belongs to you and your family, think again. As well as flies, spiders and woodlice, there are many microscopic animals and plants living with you. No matter how clean your house is, the carpets, armchairs and mattresses are probably full of tiny animals called house dust mits. These feed on the flakes of skin that you shed every day. Before the mite get to them, these bits of skin provide food for microscopic moulds, and the mites eat the moulds along with the skin. As long as you are not allergic to moulds or dust mites, neither will do you any harm.

Unseen in the pond
A drop of pond water can be full of the most astonishing animals and plants, visible only with a microscope.

Thursday, November 22, 2007


A huge part of the living world is too small to be seen except under a microscope, which magnifies everything tens or even thousands of time. Some of these microscopic creatures are harmful to us, causing diseases or making food rot. Others are useful, such as the yeast that help us make bread, and the bacteria that make yogurt and cheese.

What's living on you?
In the wild, most animals have fleas, lice and other small parasites living on their bodies. The same was true of our ancestors. A large, warm-blooded creature such as a human being is like a walking restaurant to smaller forms of life, and the meals are all free. Today we use soap and water to get rid of these small parasites from our bodies and our clothes, and if all else fails we use chemicals to kill them. But there are many microscopic creature sharing our lives that we do not even know about. Most of them do us no harm at all. Some are even beneficial, such as a bacteria which live on our skins and in our intestines.
What is coal?
Coal is just old wood, twigs and leaves. It began as forests, which grew in swampy land more than 300 million years ago. When the trees died they fell into the swamp water, which prevented them from breaking down properly. They turned into peat, a soft brown substance. The huge pressure of rock layers building up above turned the peat into coal.

Prehistoric plants
Animals are not the only things that can turn into fossils. Coal sometimes contains the fossilised bark and leaves of giant ferns and clubmosses, trees that grew in swampy forests more than 300 million years ago.

Tracks through time
Animal footprints can be preserved in the rocks, and so can insect trails or even the traces left on the seabed by worms and jellyfish. However, these small, delicate structures can only be preserved in rock that originally comes from mud or sand.

Wednesday, November 21, 2007

Fossils within fossils
Sometimes, a fossil animal is found with another fossil animal inside it. The larger animal may have been pregnant with young at the time it died, in which case the animal inside is an unborn baby animal. In other cases, the animal inside was eaten by the larger animal just before the larger animal died, and become fossilised with it.

Do dead animal always turn into fossils?
When animal die, the bone are usually chewed by other, scavenging animals, scattered by the rain and wind, or bleached broken down to dust by the Sun. For this reason, the bones of most animals that have ever lived, nomore than one in a million has survived as a fossil. Fossil form only when a dead animal is buried quickly by sediments, before there is a chance for the bones to be destroyed. When this happen, the bones are locked up in the sediment as it slowly turns to rock. The bones themselves also turn to rock in the process, but they keep their shape. Millions of years later, erosion strips away the layer of rock and exposes the fossil.
Four fossils form
1. Cover up :
The dinosaur lies on the mud in shallow water, which keeps scavenging animal away.

2. Rot set in :
Sediment starts to settle on the dinosaurs body. Meanwhile, bacteria attack the body's soft
parts, making them rot away.

3. Dead and buried :
After hundreds of years, the bones are safely buried beneath the surface. Water
seeps into the bones, leaving behind minerals that help to turn the bones into fossils.

4. Finished fossil :
As a sediment piles up, pressure grows. After thousands of years, this turns the sediment
and fossils into rock.

What are the best places to find fossils?
Fossils are found in rocks such as chalk, limestone, sandstone and shale. These were formed long ago by sediments building up on the seabed or at the bottoms of lakes. They are called 'sedimentary rocks' Rocks form by volcanic action, such as granite and basalt, do not contain fossils. You can find fossils where sedimentary rocks are being cut away by erosion, such as in sea cliffs or river gorges.

Tuesday, November 20, 2007


No one has ever seen a tyrannosaurus, or any other dinosaur, but we know a lot about them. Almost all our knowledge about prehistoric animal comes from fossils, which are rock-like 'model' of the bones of animals. The bone themselves were buried in layers of mud or sand, millions of years ago, and then slowly turned to rock themselves by a natural chemical process. Very rarely, softer parts of the body such as skin, feathers and fur also become fossilised, giving many useful clues about life in the past.

How fossils form?
If a dinosaur dies beside a lake and falls into the shallow water, it has a very good chance of slowly turning into a fossil. The dinosaur's body is slowly covered by muddy sediment. Its skin and flesh start to rot away, leaving just the bare bones are completely covered up, they do not break down any more. Instead, they are slowly fossilised, or turned into rock.

Monday, November 19, 2007

Why do some animals become extinct?
Some creatures die out, or become extinct, while others flourish. This is part of the process of evolution. Successful species move into new areas, or start eating new food, or adapt to a change in climate, and so evolve into new forms. The extinctions make space for new species to emerge. Human activities such as forest clearance, building and road-making, which are not part of a natural process, are now also causing extinctions, too quickly for evolution to fill the gaps. We are now losing thousands of species every day, and they are not being replaced.

Sunday, November 18, 2007

Why does a pangolin look like an armadillo?
Sometimes animals that live in the same way and eat much the same food evolve to look like each other, even though they are not closely related. The armadillo's main diet is ants and termites, which it digs out of the ground with powerful claws. It has a long snout for nosing around in the ground after insects, and thick plates of bone protecting its skin from the ants painful stings. This bony armour also gives it protection from predators out on the open plains where the ant nests are found. Armadillos live only in the Americas, but in Africa there are animals called pangolins that look remarkable similar. They, too, live out on the plains and feed mainly on termites and ants. The pangolins and armadillos are not related, but because they live the same kind of life, they have evolved along similar lines. This is called convergent evolution.