A Report On Bats- Essay, Research Paper

A Report on Bats-

INTRODUCTION

There is an abundant amount of animal species in the

world. They all have adapted and evolved to survive in

their surroundings. Some have grown fins, others legs, and

still others wings. One of the animals that has grown wings

is the bat. The bat is a truly great creature. It has all

the characteristics of mammals while also possessing the

skill of a bird in flight.

There are more than 800 species of bats in the

world. They are of many different sizes, shapes, and

lifestyles. They live all over the world and have drawn the

curiosity of millions. Bats also have the unique feature of

echolocation that it uses to catch insects. Though other

mammals, like the flying squirrel seem to fly but actually

glide, the bat is the only mammal that can truly fly (Lauber

1968).

A BAT’S BODY

Due to the great variety of species of bats some

characteristics vary greatly, but the Little Brown Bat is a

good example of a common bat. It has fur on the body, large

naked ears, the rear legs have claws, a tail membrane, and

it has the most distinguishing feature of a bat, wings

(Lauber 1968). The upper arm of the bat is short while the

forearm is very long (Fig. 1). The wrist is very small and

from it comes the thumb and the four longer fingers. The

thumb is short and used for climbing or walking. The

fingers are long and thin. Interlocking the fingers is the

wing. This arrangement of having the fingers in the wing

gives the bat amazing flight maneuverability (Honders 1975).

These bones look similar to a human hand. They are

connected by rubbery skin to the bat’s body enveloping all

the fingers but the thumb (Anonymous 1990).

Echolocation

Bats have a sixth sense called echolocation. This

was first proved by Donald Griffin. Bats produce ultrasonic

sound waves and then use the echo of the returning sound to

sense the world around them and in particularly to catch

insects. These sounds are usually out of the humans range

of hearing (Fellman 1993). This system is similar to that

of dolphins. The sound is in the form of clicks that

increase as the bat gets closer to the insect or whatever it

is tracking (Anonymous 1990).

Unlike humans, most insects can hear the bat’s

echolocation sounds. David D. Yager of the University of

Maryland has found that the praying mantis has used this to

its advantage. When being pursued by a bat the mantis can

hear the clicks of the bat behind it and to avoid being

eaten goes into a series of evasive maneuvers. First they

extend their fore limbs, then they extend their abdomens

which stop them. Then they go into a dive achieving a pace

twice their usual speed and if still being pursued will

crash into the ground to avoid being eaten. This and other

insects also use hearing to their advantage (Amato 1991).

Moths also do amazing maneuvers in attempts of escape,

similar to the mantis. Tiger moths even make their own

ultrasonic clicks. It is not known whether these are to

startle the bat or to warn it that the moth is distasteful

(Fellman 1993).

Despite the insects great efforts to foil the bat s

sonar the bat still catches its prey more than fifty percent

of the time (Fellman 1993). Some bats even have different

frequencies than insects can hear. The competition between

insects and bats will go on forever because they will

counter each other’s counter measures by evolving new

strategies, and as James Fullard said Evolution never

stops.

HIBERNATION AND MIGRATION

The food of bat usually becomes scarce during winter

months so some bats hibernate while others migrate (Honders

1975 and Bourliere 1995). When bats migrate they usually

move from the South to far North during the summer and they

return during the fall. Bats that hibernate prepare for the

winter by getting fat in autumn. Then they fall into a

sleep more extreme than their normal daily sleep. As in

most animals, when hibernating their major bodily functions,

such as heart-rate and breathing, are suppressed greatly.

Bats are known to interrupt their hibernation because they

have been seen in the winter.

Disturbing bats during hibernation can be very

destructive (Pistorius 1994). This is because the bats have

a limited supply of energy. The energy used when the bat is

awake is huge compared to that when it is hibernating. Bats

arise on occasion anyway to groom, or sometimes take a

flight outside, and even to move to colder places, where

they can survive with lower metabolism and save energy.

Repeated awakenings can result in starvation during the late

winter from lack of energy stores. In an extreme case in

Kentucky, during the 1960 s where a cave was a tourist

attraction, the population of 100,000 bats starved to death

after being awakened on several occasions.

REPRODUCTION

Bats have internal fertilization and give birth to

highly matured young like humans (Lauber 1968, Honders 1975,

and Ezzel 1992). Most bats only have one baby a year. The

bats mate in the roost and have little or no courtship. The

pregnant mothers form separate nursing colonies from the

others. Some species like the Mexican free-tailed bat, who

migrate immediately after mating, produce a secretion that

preserves the male s sperm until they reach their new roost.

When their baby is being born the mother hangs by

her thumbs to a tree branch. Its tail membrane acts as a

cradle and the baby is born into it tail first. Then the

mother hangs by one wing and cleans the baby with the other.

It is then attached to the mother s teat where it will hold

on during flight. In some species the baby is left at the

roost when the mother is hunting, in others the baby is

taken along. In the species that carry their young

eventually the baby grows too big for the mother and is left

in the roost. The bat then learns to fly and hunt its prey

by itself (Lauber 1968).

SPECIALIZED BATS

Some bats have developed special ways of adapting to

their surroundings. Though most bats eat insects, some feed

on fruit, nectar, small vertebrates, fish, and blood

(Bourliere 1995). The bats that eat fruit help disperse

seeds by eating and then dropping the seeds in their

droppings during flight. Those that drink nectar act like

hummingbirds pollinating flowers (Anonymous 1991). Bats

that eat small vertebrates along with insects and fruit are

often called false vampires. These bats eat lizards, tree

frogs, birds, rodents, and smaller bats. They kill their

prey by using their strong jaws and teeth to break their

neck. These bats have only about a two foot wingspan so

their prey tends to be small. Bats that catch fish fly just

above the water and catch the fish with its hind feet and

use its sharp claws to hold it. It then maneuvers the fish

to kill it by biting it (Novick 1973).

The most famous of bats is probably the vampire.

The vampire bat drinks the blood of large vertebrates when

they are asleep. To help in doing this they have developed

large incisors, a specialized tongue, and specialized saliva

to prevent blood from clotting. They are also able to move

quickly on the ground in case of their prey waking up and it

is too full of blood to fly away (Honders 1975).

MYTHS

There are many misconceptions about bats (Anonymous

1990). People think they are all dangerous because they

carry rabies. Less than one percent of all bats is infected

with rabies. Some people think they become caught in

people s hair, but this is also untrue. Other people think

lots of bats drink blood but this is also untrue, only three

species of bats drink blood. These prefer cattle blood and

only live in Latin America.

Bats are actual quite helpful to humans (Van Dyke

1994). Bats are important to many plants in the United

States because they help pollinate flowers. Most bats eat

insects, this is extremely helpful to humans. They help

keep bug populations low. Some bats, such as the little

brown bat, can consume about 600 mosquitoes in an hour.

Bats also keep the population down of other potential pests

such as leafhoppers, cucumber beetles, and June bugs.

Despite bats being helpful they can still be

dangerous under certain conditions (Anonymous 1988). Bat

droppings, or guano, are known to have spores and fungus in

them that cause Histoplasmosis, a lung infection, and other

diseases. Rabid bats can also be a threat because if one

attacks the victim can easily be infected with rabies. If

anyone ever has to handle a bat always wear gloves to

prevent bites.

Bats are a good example of how an animal can evolve

to have amazing abilities. Bats have evolved to fly, use

echolocation, hibernate, sleep in the day, hang by their

feet, and many other things that individual species have

developed. Some large bats, called megabats, are even

thought by some scientists to be closely related to primates

because of their similar brain tissue. Bats are highly

evolved animals that have amazing characteristics (Gibbons

1992 and Bailey et al. 1992).

LITERATURE CITED

Anonymous. 1988. Bats. Pamphlet distributed by Missouri Department

of Health. pp 1-2.

Anonymous. 1990. Bats In Connecticut. Pamphlet from Connecticut

Department of Environmental Protection. pp 1-8.

Anonymous. 1991. Warning From Bat Conservation International.

Pamphlet from Animal Welfare Institution. pp 1.

Amato, I. 1991. Praying Mantises Play Top Gun . Science 252: 781

Bailey, W. et al. 1992. Rejection Of The Flying Primate

Hypothesis . Science 256: 86-89

Bourliere, F. 1995. Mammals of The World. Alfred A. Knopf, New

York. pp 190-196

Ezzel, C. 1992. Cave Creatures . Science News 141: 88-90

Fellman, B. 1993. Guess Who s Coming to Dinner . National Wildlife

31: 42-45

Gibbons, A. 1992. Is Flying Primate Hypothesis Headed for a Crash

Landing? . Science 256: 34

Honders, J. 1975. The World of Mammals. Peebles Press, New York.

pp 22-23.

Lauber, P. 1968. Bats Wings in the Night. Random House, New York.

pp 1-15

Novick, A. 1973. Bats Aren t All Bad . National Geographic 143:

615- 627.

Pistoris, A. 1994. Forever Protected . Harrowsmith Country Life

28-35.

Van Dyke, L. 1994. Batting Down Bugs . Sierra Magazine 36-68