Capital
Ljubljana
Form of
government
Republic
Major cities
Ljubljana, Maribor,
Celje, Kranj,
Velenje
110 Slovenia BRITANNICA STUDENT ENCYCLOPEDIA
Smallpox
Smallpox is a dangerous disease caused
by a tiny germ called a virus. Smallpox
once killed or scarred many people.
However, in the late 20th century scientists
fought the disease successfully.
There have been no naturally occurring
cases of smallpox since the 1970s.
People who have the smallpox virus can
spread it to other people through their
breath or saliva. The virus also can live
on bedding or clothing. Once a person
is infected by the smallpox virus, there is
no cure for the disease.
People with smallpox get a high fever.
They also get body aches and become
very tired. A rash appears on the skin.
The rash changes into blisters. People
can die from smallpox. People who survive
may suffer permanent damage such
as scars or blindness.
Smallpox existed for thousands of years
in Europe, Asia, and Africa. Explorers
brought the disease to the Americas after
1492. Many Native Americans died
from it. Large outbreaks of smallpox
happened around the world.
In 1796 an English doctor named
Edward Jenner discovered a smallpox
vaccine. A vaccine is a substance that
prevents people from getting a disease.
In 1967 a group called theWorld
Health Organization began giving the
smallpox vaccine to people around the
world. The project was a success. By
1979 there were no cases of smallpox
anywhere in the world.
#More to explore
Disease, Human • Vaccine • Virus
Snail and Slug
Snails and slugs are similar animals. The
main difference between them is that a
snail has a shell and a slug does not.
Snails and slugs belong to the group of
soft-bodied animals called mollusks,
which also includes oysters, clams, and
squid.
Snails and slugs are found throughout
the world. Some live on land or in trees.
Others live in water. Some snails and
slugs spend the winter underground.
Most snails and slugs are small and drab.
A snail has a coiled body and shell. The
shell protects the snail from heat and
enemies. Snails can make their shells
A doctor gives a girl a shot of a vaccine in
the 1960s to protect her against smallpox.
Doctors vaccinated so many people that
today the chances of catching the disease
are very small.
BRITANNICA STUDENT ENCYCLOPEDIA Snail and Slug 111
bigger as they grow. Slugs have straight
bodies. Both snails and slugs have two
long tentacles sticking out from the
head. Each tentacle has an eye at the tip.
Snails and slugs move by gliding on a
foot. They make a slimy fluid that helps
the foot glide.
Snails and slugs eat plants. Slugs also eat
dead animal material and sometimes
worms and snails. Snails and slugs are
eaten by snakes, toads, turtles, beetles,
and birds.
Gardeners consider snails and slugs to be
pests. But people eat some types of land
snails, especially in France.
#More to explore
Mollusk • Shell
Snake
A snake is a reptile with a long, slender
body but no arms or legs. Snakes are
closely related to lizards. There are about
2,900 species, or kinds, of snake. The
best-known snakes include cobras,
vipers, boas, and pythons.
Where Snakes Live
Snakes are found throughout the world
except near the North and South poles.
The tropics have the greatest variety.
Most snakes live on the ground, but
others prefer trees. Some snakes spend
their whole lives in underground tunnels.
Sea snakes live in water.
Physical Features
Snakes are vertebrates, or animals with a
backbone. The backbone is long and
flexible. Snakes grow throughout their
lives. The longest known snake is the
reticulated python, which can grow to
32 feet (10 meters). The giant anaconda
is usually not as long but is much
heavier. The smallest snakes are the
blind snakes. Some of them are barely 4
inches (10 centimeters) long.
Snakes are covered with rows of scales.
Scales are hardened folds in the outer
layer of skin. A scale can be shiny and
smooth, or it can have a ridge running
down the middle. A snake molts, or
sheds its skin, many times during its life.
Snakes have no ears or eyelids. Clear
scales cover the eyes. A snake’s mouth
opens wide because the lower and upper
jaw can separate. Most snakes have long,
needle-sharp teeth that curve backward.
Some snakes, including cobras and
rattlesnakes, have a long front or back
pair of teeth called fangs. A snake’s
tongue is forked.
A snail glides along the surface of a leaf.
112 Snake BRITANNICA STUDENT ENCYCLOPEDIA
Snakes come in many different sizes and colors.
BRITANNICA STUDENT ENCYCLOPEDIA Snake 113
Behavior
Snakes eat mice, rats, birds, frogs, fish,
insects, lizards, eggs, and sometimes
other snakes. Most snakes swallow their
prey whole, usually head first. The prey
may be dead or alive when eaten. Boas,
pythons, king snakes, and rat snakes are
called constrictors. They coil around
their prey and constrict, or squeeze, the
animal to death before eating it. Vipers
and cobras kill their prey by shooting
venom, or poison, into it through their
fangs.
Without ears, snakes cannot hear most
sounds. But they can sense when prey is
near through vibrations in the ground.
