| Bats
account for nearly one quarter of all mammals, with almost
1,000 species worldwide. Bats have a rapid metabolism and
consume a lot of food for their size. The effort of flight,
and the need for some species to migrate or hibernate during
the winter, contribute to their large appetites. About 70 percent
of the world's bats eat insects. Small bats live in cooler
to moderate climates such as the U.S. and Europe and, for
the most part, feed on insects that fly at dusk or dark. Some
bats eat small aquatic animals like fish and frogs.
About
20 percent of the world's bats eat ripe fruit and the nectar
from night blooming flowers. These tend to be the larger
bats that live in warm tropical climates and can have a
wingspan of up to six feet.
There
are only three species of vampire bats, which drink the
blood of large animals. The saliva of vampire bats contains
a blood-thinning agent that is 20 times stronger than any
other known anticoagulant. This agent may one day help thin
the blood of people who are at risk for heart attacks or
strokes.
Although
bats have reasonably good eyesight, many have the added
skill of echolocation. Similar to the sonar used by whales,
porpoises, dolphins, seals, shrews, and some birds, bats
also let out ultrasonic (high-frequency) pulsing sounds
from their mouth or nose. The sound bounces off obstacles
and food and echoes back to the bat giving it information
about the size, shape, identity, and location of the object.
Modern radar used by highway patrol personnel is based on
this same principle.
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