BatsINTRODUCTIONThere are an innumerous amount of animal species in the world. They allhave 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 isthe bat. The bat is a truly great creature. It has all the characteristics ofmammals while also possessing the skill in flight of a bird.
There are more than 800 species of bats in the world. They are of manydifferent sizes, shapes, and lifestyles. They live all over the world and havedrawn the curiosity of millions. Bats also have the unique quality ofecholocation that it uses to catch insects. Though other mammals, like theflying squirrel seem to fly but actually glide the bat is the only mammal thatcan truly fly (Lauber 1).
A Bats BodyDue to the great variety of species of bats some characteristics varygreatly but the Little Brown Bat is a good example of a bat. It has fur on itsbody, large naked ears, its rear legs have claws, it has a tail membrane, andit has the most distinguishing feature of a bat, wings (Lauber 9). The upperarm of the bat is short while the forearm is very long. The wrist is verysmall and from it comes the thumb and the four longer fingers. The thumb isshort and used for climbing or walking. The fingers are long and thin.
Interlocking the fingers is the wing. This set up of having the fingers in thewing gives the bat amazing flight maneuverability (Honders 22). These boneslook similar to a human hand. They are connected by rubbery skin to the bat’sbody enveloping all the fingers but the thumb (Bats in CT 1).
EcholocationBats have a “sixth sense” called echolocation. This was first proved byDonald Griffin. Bats produce ultrasonic sound waves and then use the echo ofthe returning sound to sense the world around them and in particularly to catchinsects. These sounds are usually out of the humans range of hearing (Fellman42). This system is similar to that of dolphins. The sound is in the form ofclicks that increase as the bat gets closer to the insect or whatever it istracking (Bats in CT).
Unlike humans most insects can hear the bat’s echolocation sounds.
David D. Yager of the University of Maryland has found that the praying mantishas used this to its advantage. When being pursued by a bat the mantis can hearthe clicks of the bat behind it and to avoid being eaten goes into a series ofevasive maneuvers. First they extend their fore limbs and then extend theirabdomens that stops them. Then they go into a dive going twice their usualspeed 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 781). Mothsalso do amazing maneuvers in attempts of escape similar to the mantis. Tigermoths even make their own ultrasonic clicks. It is not known whether these areto startle the bat or to warn it that the moth is distasteful.
Despite the insects great efforts to foil the bats sonar the bat stillcatches its prey more than 50% of the time (Fellman 93). Some bats even havedifferent frequencies than insects can hear. The competition between insectsand bats will go on forever because they will counter each others countermeasures of how an animal can evolve to how amazing abilities. Bats haveevolved to fly, use echolocation, hibernate, sleep in the day, hang by theirfeet, and many other things that individual species have developed. Some largebats, called megabats, are even thought by some scientists to be closely relatedto primates because of their similar brain tissue. Bats are highly evolvedanimals that have amazing characteristics.
(Gibbons 1992, Bailey et al. 1992)HIBERNATION AND MIGRATIONThe food of bat usually becomes scarce during winter months so some batshibernate while others migrate (Honders 75, Bourliere 95). When bats migratethey usually move from the south to far north during the summer and they returnduring the fall. Bats that hibernate prepare for the winter by getting fat inautumn. Then they fall into a sleep more extreme than their normal daily sleep.
As in most animals, when hibernating their major bodily functions, such asheart-rate and breathing, are suppressed greatly. Bats are known to interrupttheir hibernation because they have been seen in the winter.
Disturbing bats during hibernation can be very destructive (Pistorius94). This is because the bats have a limited supply of energy. The energyused 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, andeven to move to colder places, where they can survive with lower metabolism andsave energy. Repeated awakenings can result in starvation in the late winterfrom lack of energy stores. In an extreme case in Kentucky, during the 1960swhere a cave was a tourist attraction ,the population of 100,000 bats starved todeath after being awakened so many times.
REPRODUCTIONBats have internal fertilization and give birth to highly matured younglike humans (Lauber, Honders 75, Ezzel 92). Most bats only have one baby a year.
The bats mate in the roost and have little or no courtship. The pregnantmothers form separate nursing colonies from the others. Some species like theMexican free-tailed bat, who migrate immediately after mating, produce asecretion that preserves the males sperm until they reach their new roost. Whentheir baby is being born the mother hangs by her thumbs to a tree branch. Itstail membrane acts as a cradle and the baby is born into it tail first. Thenthe mother hangs by one wing and cleans the baby with the other. IT is thenattached to the mothers teat where it will hold on during flight. In somespecies the baby is left at the roost when the mother is hunting, in others thebaby is taken along. In the species that carry their young eventually the babygrows to big for the mother and is left in the roost. The bat then learns tofly and hunt its prey by itself (Lauber).
SPECIALIZED BATSSome 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 95). The bats that eat fruit help disperse seeds by eatingfruit and then dropping the seeds in their droppings during flight. Those thatdrink nectar act like hummingbirds pollinating flowers (Warning from BatConservation International 91). Bats that eat small vertebrates along withinsects and fruit are often called false vampires. These bats eat lizards, treefrogs, birds, rodents, and smaller bats. They kill their prey by using thierstrong jaws and teeth to break their neck. These bats have only about a twofoot wingspan so thier prey tends to be small. Bats that catch fish fly justabove the water and catch the fish with its hind feet and use its sharp claws tohold it. It then maneuvers the fish to kill it by biting it (Novick 73).
The most famous of bats is probably the vampire. The vampire bat drinksthe blood of large vertebrates, to do this they have developed large incisors,a specialized tongue, and specialized saliva to prevent blood from clotting, andthey are able to move quickly on the ground in the case of its prey waking upand it is too full to fly away (Honders 75).