123CytoplasmThere are around 30,000
species of tick and mite, most of
which are less than^1 ⁄ 32 in (1 mm)
long. They can be found in stored
food such as flour and cheese; in
animal dung; and skin, hair, and fur.
They feed on plants and on the
skin and blood of host
animals.7
/ (^7)
LIVING WORLD
GROWING
Noctiluca algae are also
responsible for “red tides.”
These are usually caused,
for example, by sewage or
fertilizer. Algae growing
in this way can kill other
life-forms.
MICROLIFE
MINI MONSTERS
Ticks and mites belong to the same
class of invertebrate as spiders, the
arachnids. They are parasites, living
and feeding on plants or other
animals, known as hosts. Some
species destroy crops, while others
pass on diseases.
Eyelash mites
You won’t be able to see them or feel
them, but living on your face are
tiny,^7 ⁄1,000 in- (0.2 mm-) long mites
called Demodex folliculorum. The
mites cling to eyelashes, to feed on
dead skin cells at the eyelash roots—
but don’t worry, they are harmless.
MEAL
MITE
Many of the
foods you eat
probably contain
the remains of mites
like this one, which
feeds on stored cereal
products such as flour
and oatmeal.
BRILLIANT BACTERIA
Bacteria are an essential part of
life on Earth. Some types live in
soil and release nitrates, without
which plants would not grow and
the food chain would collapse.
Other types live in your
intestines, helping you digest
your food. But bacteria can also
be harmful, causing dangerous
diseases in all kinds of plants and
animals, including people.
POWERFUL PENICILLIN
If you have an illness, your
doctor might give you penicillin.
This is an antibiotic—a
medicine that kills bacteria.
In 1928, scientist Alexander
Fleming found a dish of bacteria
with a type of mold growing
on it. Where the mold grew,
the bacteria had died. From
this discovery, Fleming
Cell developed penicillin.
wall
Cell membrane
Flagellum
In 1862, French scientist
Louis Pasteur created a
way of killing bacteria
with heat. This process,
called pasteurization, is
still used today.
TELL ME MORE...
Penicillin colony
A DUST MITE
can fit on the tip
of a needle.
This tiny
creature eats
fragments of
dead skin and
hair found in
house dust.
Bacterial
cell
CRAB LARVA Many
animals start life as
microscopic larvae. Crab
larvae find a place to settle as
a tiny crab, where they can
then grow to be an adult.
(c) 2012 Dorling Kindersley. All Rights Reserved.(c) 2012 Dorling Kindersley. All Rights Reserved.