Mammals - A Multimedia Encyclopedia/Mammals.bin/mammals/bats/bats.dat

Text File | 1990-06-20 | 5KB | 167 lines

BAT

  In ghost stories, no haunted house
is complete without a few bats
flying around. Halloween, too,
brings to mind images of witches,
goblins, and bats. Bats seem
frightening and mysterious. They
dart around at night, hang upside
down in caves, and roost in
abandoned buildings. But most
stories about bats aren't true. Bats
don't get tangled in people's hair.
And they are not blind.

  All bats can see, but many do not
use their eyes to find food.
Instead, they use their ears. Even
in the dark, a bat can find its way,
can avoid obstacles, and can detect
food by using %f,10,g\echoloca%echolocation (say
ek-oh-low-KAY-shun). When flying, a
bat sends out a series of short,
high-pitched beeping sounds through
its mouth or its nose. It listens
for the echoes that bounce back when
the beeps hit an object. From these
echoes, a bat can tell where an
object is and whether it is moving.
Sonar systems used by submarines to
locate other ships work in the same
way. The tones of the beeping sounds
that each kind of bat produces are
different. People don't notice the
sounds that most bats make because
they are beyond the range of human
hearing.

  Bats are the only %f,10,h\mammal%mammals in the
world that can fly. Colugos and
flying squirrels can move through
the air, but they really only glide.
Bats flap their wings and fly like
birds. Two delicate layers of skin
stretch from the sides of a bat's
body to the ends of its long finger
bones. The wings are moved by
powerful muscles that help the
animal fly easily through the air.
Some bats can fly 40 miles (64 km)
an hour or more.

  Bats exhibit incredible variety.
Their %f,10,h\wingspan%wingspans range from 6 inches
(15 cm) to 6 feet (183 cm). Some
bats have tails, and some do not.
Scientists divide bats into two
groups. In one group are the
microchiropterans (say
my-crow-kye-ROP-tuh-runs). Bats in
this group tend to be small. They
have large ears and small eyes.
Microchiropterans use echolocation
to fly and locate food. In the other
group are the megachiropterans (say
meg-uh-kye-ROP-tuh -runs). These
bats are usually larger. They have
small ears and large eyes and look
like small foxes. Most
megachiropterans fly by sight and do
not use echolocation.

  Most bats are microchiropterans.
These bats feed mainly on insects
and other small animals. Some
microchiropterans also feed on fruit
and flowers.

  Some bats that live in colder
areas %f,10,h\migratio%migrate to warmer places
before winter arrives and food
becomes hard to find. Others sleep
for months at a time. This kind of
sleep is called %f,10,g\hibernat%hibernation (say
hye-bur-NAY-shun). When a bat
hibernates, its body temperature
drops. Its heart rate and breathing
slow down. It lives off fat stored
in its body.

  Most megachiropterans live in
tropical Africa, Asia, and
Australia. They feed mainly on fruit
and flowers. Most fruit- and
flower-feeding bats--large or
small--are very much alike. They use
their keen sense of smell to detect
flowers and ripe fruit. To lap
nectar from inside a blossom, a
flower-feeding bat uses its pointed
snout and a tongue that may measure
one-third the length of its body.

  Insect eaters use echolocation to
find their %f,10,h\prey%prey. These bats feast on
insects that fly at night. A bat may
catch a big insect in its mouth, or
it may scoop a small insect up with a
wing and pull its victim to its
mouth. Some bats can gobble 12 or
more mosquito-size insects a minute.

  Fishing bats also hunt by
echolocation. They use their huge
claws to catch fish. Flying low over
water, these bats can detect a fish
breaking the surface. Then they
swoop down and hook their catch with
their sharp, curved claws.

  A vampire bat has razor-sharp
teeth that it uses to make a
shallow, painless cut in the skin of
its prey. With rapid licking
movements, it laps up blood from the
cut. This small bat is only about 4
inches (10 cm) long--about the size
of a mouse. But it can drink its
weight in blood--about 1 ounce (28
g)--each night. It may even drink so
much that it becomes too full to
fly. Vampire bats rarely bite
people. They often feed on the blood
of chickens, cattle, asses, and deer.
The wounds they make can become
infected. And vampire bats sometimes
carry a disease called rabies.

  Most bats have only one %f,10,h\offsprin%offspring
a year. Many kinds give birth in
caves and their offspring cluster in
%f,10,h\nursery%nurseries where large numbers of
baby bats are found. A nursery may
contain fewer than a hundred or as
many as several million females and
their young. A newborn bat clings to
its mother or to the ceiling of the
nursery. Within two to twelve weeks,
the young bats will begin to fly.

  Bats benefit people in several
ways. Some feed on harmful insects.
Others %f,10,h\pollinat%pollinate flowers as they fly
from blossom to blossom sipping
nectar. In fact, more than 130 types
of plants are dependent on bats
for pollination and would become
%f,10,g\extinct%extinct without them. Seeds dropped
by fruit bats may sprout into plants.

  Scientists are studying
echolocation. They would like to
perfect a similar system that would
allow blind people to detect objects
with sound.