Bats are somewhat difficult to study because of
their secretive, nocturnal habits and their
flight capabilities. Although well over nine hundred
species have been identified and catalogued,
additional species have since been discovered,
primarily from the South American rain forests.
New ones remain to be discovered, and the classification
of bats continues to be improved.
Bats are the most widely distributed kind of
terrestrial mammal. They are found from Alaska
to the tip of Argentina and from near the Arctic
Circle to South Africa. They occur widely through
the tropical regions and in the temperate zones.
Physical Characteristics of Bats
Although bats range in size from tiny hog-nosed
bats that weigh less than a penny to flying foxes
whose wing spans exceed five feet, the majority of
bats tend to be small. Despite variation in size, all
species of bat share the same body form, with certain
similarities in fur and skin, wings, teeth, reproductive
system and patterns, and visual and
hearing systems.
The bat's skin is black or dark grayish brown in
color, with tiny transparent hairs on the membrane
surface. While most bats have small eyes,
perhaps encouraging the misconception that bats
are blind, their auditory system is developed to an
extraordinary degree.
Of the bats who feed on animals, some feed on
insects and whole animals; vampire bats, which
occur from Mexico to Argentina, feed only on the
blood. Plant-eating bats feed on fruit and flowers.
Female bats give birth at the roost site, frequently
while hanging upside down. Bat young
are born in a breech presentation and are helpless
until they are large enough to fly. Brown bats
reach adult size and begin to fly at three to four
weeks of age.
The Behavior of Bats
The major behavioral pattern of bats is nocturnal
activity. During nocturnal flight, bats are protected
from being visually spotted by predators and from
exposure to the sun and to high temperatures,
which promote heat absorption and the loss of
body water necessary for temperature regulation.
Bats routinely seek shelter during the daylight
hours. Caves provide protection from the sun and
predators and allow bats to conserve energy under
consistent temperature and moisture conditions.
Bats also shelter in tree cavities, crevices,
buildings, and trees.
While tropical bats are active all year round,
bats in temperate regions hibernate during the
winter in order to accommodate the diminished
food supply. Most hibernating bats spend the
summer feeding heavily on insects, building up
enough fat to provide energy during hibernation.
During hibernation, the bat allows its body temperature
to fall to that of the surrounding air, and
as its pulse and breathing rates slow down, it essentially
enters a state of suspended animation.
The sole characteristic that sets bats apart from
other mammals is flight. Some bats fly high, fast,
and far, while others fly more slowly, maneuvering
around obstacles, catching
their prey on the wing, or plucking
it from the ground. Soaring is uncommon
in bats, as is swift flight in
comparison with birds. Bats fly in
flocks sometimes numbering in the
thousands, a precaution against
predators.
Microchiropteran bats use echolocation,
a pulse system of highfrequency
sounds and their echoes,
to navigate and to locate food.
Bats emit sound, then receive and
analyze the data from the returning
echoes which provide information
on direction and distance to the
target. Best suited to short distances,
echolocation is so accurate
that some bats appear able to distinguish
among individual species
of insects.
Bats are allies of human beings
in controlling the insect population.
Most species of bats found in
the United States feed on beetles,
moths, and crickets, many of
which destroy vegetation and are
damaging to agricultural interests.
Recent studies also suggest important
uses for anticoagulent compounds,
found in vampire bats' saliva,
that hinder the clotting of
blood.
Classification:
Kingdom: Animalia
Subkingdom: Metazoa
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Subclass: Theria
Order: Chiroptera (bats)
Suborders: Megachiroptera (flying foxes), Microchiroptera (bats)
Families: Pteropopidae (flying foxes, forty-four genera, 173 species);
Rhinopomatidae (mouse-tailed bats, one genus, three
species); Emballonuridae (sheath-tailed bats, thirteen genera,
fifty species); Craseonycteridae (hog-nosed bats); Nycteridae
(slit-faced bats, one genus, eleven species); Megadermatidae
(false vampire bats, four genera, five species); Rhinolophidae(
horseshoe bats, one genus, sixty-nine species); Hipposideridae
(leaf-nosed bats, nine genera, sixty-one species);
Mormoopidae (leaf-chinned bats, two genera, eight species);
Noctilionidae (bulldog bats, one genus, two species); Mystacinidae
(short-tailed bats, one genus, two species); Phyllostomidae
(spear-nosed bats, forty-seven genera, 140 species);
Desmodontinae (vampire bats, three genera, three species);
Natalidae (funnel-eared bats, one genus, eight species);
Furipteridae (thumbless bats, two genera, two species; Thyropteridae
(disk-winged bats, one genus, two species); Myzopodidae
(sucker-footed bats);Vespertilonidae (common or vesper
bats, forty-two genera, 319 species); Molossidae (free-tailed
bats, twelve genera, ninety-one species)
Geographical location: Every continent except Antarctica
Habitat: Mostly forests and deserts; some grasslands
Gestational period: Three to ten months, with delayed implantation
Life span: Generally three to five years; up to thirty years in captivity
Special anatomy: Head, body, tail, two wings, each supported by
upper arm, forearm, hand; knee joints bend backward enabling
the bat to hang upside down and still be ready to take flight
easily
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