Childrens Illustrated Encyclopedia

346

Nucleus—

control center

of amoeba

Pseudopod

(false foot)

Cell membrane,

the skin around

the cell

Pollen

Microscopic grains of

pollen grow on the male

part of a plant, called the

stamen. each kind of plant

has a different type of

pollen grain with its own

pattern and shape.

All ARoUnD US there are living things that we

cannot see because they are too small. They

float in the air, they swim in puddles and

oceans, and they coat rocks, soil, plants,

and animals. Microscopic life includes

bacteria and viruses; single-celled

organisms called protoctists; and

single-celled plants called algae.

It also includes the microscopic stages in

the lives of larger plants and animals, such

as the tiny pollen grains of flowers and

the spores of mushrooms. From bacteria

to algae, all are so small that we can see

them only through a microscope. Viruses,

which are the smallest and simplest of all

living things, must be magnified one

million times before we can see them.

Microscopic life has a crucial role to play.

Plankton consists of millions of algae and

protozoa, and is an important food for water

creatures. Bacteria in soil help to recycle nutrients.

Some microscopic life, such as bacteria, can cause disease.

AMoeBA

The amoeba is

a single-celled

organism. It lives in

ponds and puddles.

We need to magnify

an amoeba at

least one thousand times

before we can see it.

The amoeba moves by

stretching out a part of its body

known as a pseudopod, or “false

foot.” The rest of the body then

flows into the pseudopod.

Amoebas feed by engulfing prey

such as bacteria with their

pseudopods; then the whole

body flows over the prey.

Food is stored in a

small bag called

the food vacuole.

DUST MITe

This microscopic animal can

be found in anyone’s home. It lives among dust,

fluff, cat fur, and bits of dirt. Dust mites eat the

dead skin you shed every day.

Dust mite

Amoeba divides in half, forming

two daughter cells.

Passionflower

pollen grain

DIAToM

Microscopic plants called diatoms

live in lakes, rivers, and oceans. There

are thousands of different kinds of

diatoms, providing food for many

insects and water creatures. Diatoms

live and grow by using sunlight and

the nutrients in the water. Around

their bodies are strong shell-like

walls made of silica—the same

material found in sand grains.

AlgAe

The slimy scum that you see on

the surface of a stagnant pond is

blue-green algae. These algae are

not true plants. They are more

closely related to bacteria. Blue-

green algae were among the first

forms of life to appear on earth

more than 2,000 million years ago. HoW An AMoeBA RePRoDUceS

To reproduce, the amoeba divides into two. This is

called fission. First the nucleus splits in two, then the

rest of the body divides in half to form two separate

amoebas. These are called daughter cells.

Hollyhock

pollen grain

Microscopic life

Find out more

Disease

Human body

Microscopes

ocean wildlife

US_346_Microscopic_Life.indd 346 09/02/16 5:27 pm