Difference between revisions of "Bat" - New World Encyclopedia

From New World Encyclopedia
(Added article and credit tags)
 
 
(26 intermediate revisions by 7 users not shown)
Line 1: Line 1:
{{OtherUses|the mammal}}
+
{{Approved}}{{Images OK}}{{Submitted}}{{Paid}}{{Copyedited}}
{{Taxobox
+
{{Taxobox  
 
| color = pink
 
| color = pink
 
| name = Bats
 
| name = Bats
 
| fossil_range = Late [[Paleocene]] - Recent
 
| fossil_range = Late [[Paleocene]] - Recent
| image = Haeckel Chiroptera.jpg
+
| image = Big-eared-townsend-fledermaus.jpg
 
| image_width = 240px
 
| image_width = 240px
| image_caption = "Chiroptera" from [[Ernst Haeckel]]'s ''Artforms of Nature'', 1904
+
| image_caption = Townsend's Big-eared Bat, ''Corynorhinus townsendii''
| regnum = [[Animal]]ia
+
| regnum = [[Animalia]]
 
| phylum = [[Chordate|Chordata]]
 
| phylum = [[Chordate|Chordata]]
| classis = [[Mammal]]ia
+
| classis = [[Mammalia]]
 +
| infraclassis = [[Eutheria]]
 +
| superordo = [[Laurasiatheria]]
 
| ordo = '''Chiroptera'''
 
| ordo = '''Chiroptera'''
 
| ordo_authority = [[Johann Friedrich Blumenbach|Blumenbach]], 1779
 
| ordo_authority = [[Johann Friedrich Blumenbach|Blumenbach]], 1779
 
| subdivision_ranks = Suborders
 
| subdivision_ranks = Suborders
 
| subdivision =  
 
| subdivision =  
[[Megachiroptera]]<br/>
+
Megachiroptera<br/>
[[Microchiroptera]]<br/>
+
Microchiroptera<br/>
 
See text for families.
 
See text for families.
 
}}
 
}}
'''Bats''' are [[mammal]]s in the [[scientific classification|order]] '''Chiroptera'''. Their most distinguishing feature is that their forelimbs are developed as [[wing]]s, making them the only mammal capable of flight. (Other mammals, such as [[flying squirrel]]s and gliding [[phalanger]]s, can [[gliding|glide]] for limited distances but are not capable of true [[flight]]). The word ''Chiroptera'' can be translated from the [[Greek language|Greek]] words for "hand wing," as the structure of the open wing is very similar to an outspread human hand, with a [[membrane]] ([[patagium]]) between the fingers that also stretches between hand and body.
 
  
There are estimated to be about 1,100 species of bats worldwide: about 20% of all mammal species.
+
A '''bat''' is a [[mammal]] in the [[order (biology)|order]] '''Chiroptera'''. Their most distinguishing feature is that their forelimbs are developed as [[wing]]s, making them the only mammals in the world naturally capable of [[flight]]. (Other mammals, such as [[Squirrel|flying squirrel]]s, [[lemur]]s, and flying opossums, can [[gliding|glide]] for limited distances). There are estimated to be about 1,100 [[species]] of bats worldwide, accounting for about 20 percent of all mammal species (Trudge 2000).  
  
About 70 percent of bats are [[insectivorous]]. Most of the remainder feed on [[fruit]]s and their juices; three bat species eat [[blood]] and some prey on [[vertebrate]]s. These bats include the [[leaf-nosed bat]]s ([[Leaf-nosed bat|Phyllostomidae]]) of [[central America]] and [[South America]], and the related [[bulldog bat]]s ([[Noctilionidae]]) that feed on [[fish]]. There are at least two known species of bat that feed on other bats: the [[Spectral Bat]] or American False Vampire bat and the [[Ghost Bat]] of Australia.
+
Though sometimes called "flying [[rodent]]s," "flying [[mice]]," or even mistaken for [[insect]]s and [[bird]]s, bats are not, in fact, rodents.  
  
Some of the smaller bat species are important [[pollinator]]s of some tropical [[flower]]s. Indeed, many tropical plants are now found to be totally dependent on them, not just for pollination, but for spreading their [[seed]]s by eating the resulting fruits. This role explains environmental concerns when a bat is [[introduced species|introduced]] in a new setting. [[Tenerife]] provides a recent example with the introduction of the [[Egyptian bat]].
+
While in [[China]] bats are considered a sign of good fortune, in the West they often are viewed negatively, such as associated with witches or vampires. Some bat-human interactions indeed are unfavorable for humans, such as those [[fruit]]-eating bats that compete for crops and the blood consuming vampire bats that can spread [[rabies]] to humans and domestic animals. But bats as a group provide important benefits to the [[ecosystem]] and to humans. Some of the smaller bat species are important [[pollination|pollinator]]s of some tropical [[flower]]s. Indeed, many tropical plants are now found to be totally dependent on them, not just for pollination, but for spreading their [[seed]]s by eating the resulting fruits. Insect-eating bats also play an important role in controlling insect populations, including night-flying [[mosquito]]s that might be carriers of [[malaria]] and other serious diseases. Some of the larger bats are a food source, and bat droppings, or guano, are harvested for use as fertilizer.
  
==Classification==
+
Given the ability of fruit-eating bats to spread seeds, there are environmental concerns when a bat is [[introduced species|introduced]] in a new setting. [[Tenerife]] provides a recent example with the introduction of the [[Egyptian fruit bat]].
Bats are [[mammals]].  Though sometimes called "flying rodents", "flying mice," or even [[bugs]], but bats are neither [[mouse|mice]] nor [[rodent]]s.
 
There are two suborders of bats:
 
#[[Megabat|Megachiroptera]] (megabats)
 
#[[Microbat|Microchiroptera]] (microbats/echolocating bats)
 
Despite the name, not all megabats are larger than microbats. The major distinction between the two suborders is based on other factors:
 
*Microbats use [[Animal echolocation|echolocation]], whereas megabats do not (except for ''[[Rousettus]]'' and relatives, which do).
 
*Microbats lack the [[claw]] at the second [[toe]] of the [[forelimb]].  
 
*The [[ear]]s of microbats don't form a closed ring, but the edges are separated from each other at the base of the ear.
 
*Microbats lack [[underfur]]; they have only guard hairs or are naked.  
 
  
[[Image:Big-eared-townsend-fledermaus.jpg|thumb|240px|[[Townsends's Big-eared Bat]], ''Corynorhinus townsendii'']]
+
The word ''Chiroptera'' can be translated from the [[Greek language|Greek]] words for "hand wing," as the structure of the open wing is very similar to an outspread human hand with a [[skin|membrane]] (patagium) between the fingers that also stretches between hand and body.
  
Megabats eat fruit, nectar or pollen while microbats eat [[insects]], [[blood]] (small quantities of  blood of animals), small mammals, and [[fish]], relying on [[animal echolocation|echolocation]] for navigation and finding prey.
+
==Megabats versus microbats==
  
Genetic evidence, however, indicates that some microbats ("Yinochiroptera") are more closely related to megabats than to the other microbats ("Yangochiroptera"). There is some morphological evidence that Megachiroptera evolved flight separately from Microchiroptera; if so, the Microchiroptera would have uncertain affinities. When adaptations to flight are discounted in a [[cladistic]] analysis, the Megachiroptera are allied to the primates by anatomical features that are not shared with Microchiroptera.
+
Bats are divided into two distinct groups (or suborders):
  
Little is known about the evolution of bats, since their small, delicate skeletons do not fossilize well. However a late Cretaceous tooth from South America resembles that of an early Microchiropteran bat. The oldest known definite bat fossils, such as ''Icaronycteris'', ''Archaeonycteris'', ''Palaeochiropteryx'' and ''Hassianycteris'', are from the early [[Eocene]] (about 50 million years ago), but they were already very similar to modern microbats. ''Archaeopteropus'', formerly classified as the earliest known megachiropteran, is now classified as a microchiropteran.
+
* '''Megachiroptera''' (megabats)
 +
* '''Microchiroptera''' (microbats/echolocating bats)
  
Bats are traditionally grouped with the tree shrews ([[Scandentia]]), colugos ([[Dermoptera]]), and the [[primate]]s in superorder [[Archonta]] because of the similarities between Megachiroptera and these mammals. However, molecular studies have placed them as sister group to [[Ferungulata]], a large grouping including [[carnivora]]ns, [[Pholidota|pangolins]], [[Perissodactyla|odd-toed ungulates]], [[Artiodactyla|even-toed ungulates]], and [[Cetacea|whales]].
+
Despite the name, not all megabats are larger than microbats. The major distinction between the two suborders is based on other factors:
 +
* Microbats use [[Animal echolocation|echolocation]], whereas megabats do not (except for ''[[Rousettus]]'' and relatives, which do).
 +
* Microbats lack the [[claw]] at the second [[toe]] of the [[forelimb]].
 +
* The [[ear]]s of microbats do not form a closed ring, but the edges are separated from each other at the base of the ear.
 +
* Microbats lack [[underfur]]; they have only [[guard hair]]s or are naked.  
  
*'''ORDER CHIROPTERA''' (Ky-rop`ter-a) (Gr. ''cheir'', hand, + ''pteron'', wing)
+
Megabats are found in [[Africa]] and [[Asia]]. They eat [[fruit]], [[nectar]] or [[pollen]], with some supplementing their diets with a few insects. Some megabat species are known as '''flying foxes.''' There are about 170 species of megabats. Microbats are found on all continents except [[Antarctica]]. Most of them eat [[insect]]s, while a few eat fruit, nectar, or small animals, or drink the [[blood]] of large animals. There are about 800 species of microbats (Richardson 2002).
**'''Suborder [[Megachiroptera]] ([[megabat]]s)''' [[Image:Golden crowned fruit bat.jpg|thumb|[[Giant golden-crowned flying fox]], ''Acerodon jubatus'']]
 
*** [[Pteropodidae]]
 
**'''Suborder [[Microchiroptera]] ([[microbat]]s)'''
 
*** Superfamily ''[[Emballonuroidea]]''
 
**** [[Emballonuridae]] ([[Sac-winged bat|Sac-winged]] or [[Sheath-tailed bat]]s)
 
*** Superfamily ''[[Rhinopomatoidea]]''
 
**** [[Rhinopomatidae]] ([[Mouse-tailed bat]]s)
 
**** [[Craseonycteridae]] ([[Bumblebee Bat]] or [[Kitti's Hog-nosed Bat]])
 
*** Superfamily ''Rhinolophoidea''
 
**** [[Rhinolophidae]] ([[Horseshoe bat]]s)
 
**** [[Nycteridae]] ([[Hollow-faced bat|Hollow-faced]] or [[Slit-faced bat]]s)
 
**** [[Megadermatidae]] ([[False vampire]]s)
 
*** Superfamily ''[[Vespertilionoidea]]''
 
**** [[Vespertilionidae]] ([[Vesper bat]]s or [[Evening bat]]s) [[Image:Vespertilio murinus.jpg|thumb|[[Parti-coloured bat]], ''Vespertilio murinus'']] [[Image:Pipistrellus pipistrellus01.jpg|thumb|[[Common Pipistrelle]], ''Pipistrellus pipistrellus'']]
 
*** Superfamily ''[[Molossoidea]]''
 
**** [[Molossidae]] ([[Free-tailed bat]]s)
 
**** [[Antrozoidae]] ([[Pallid bat]]s)
 
*** Superfamily ''[[Nataloidea]]''
 
**** [[Natalidae]] ([[Funnel-eared bat]]s)
 
**** [[Myzopodidae]] ([[Sucker-footed bat]]s)
 
**** [[Thyropteridae]] ([[Disk-winged bat]]s)
 
**** [[Furipteridae]] ([[Smoky bat]]s)
 
*** Superfamily ''[[Noctilionoidea]]''
 
**** [[Noctilionidae]] ([[Bulldog bat]]s or [[Fisherman bat]]s)
 
**** [[Mystacinidae]] ([[New Zealand short-tailed bat]]s)
 
**** [[Mormoopidae]] ([[Ghost-faced bat|Ghost-faced]] or [[Moustached bat]]s)
 
**** [[Phyllostomidae]] ([[Leaf-nosed bat]]s) ''This family contains (among others) the [[Vampire bat]]s''
 
  
Most microbats are active at night or at twilight. By emitting high-pitched sounds and listening to the echoes, the [[microbat]]s locate prey and other nearby objects. This is the process of [[animal echolocation|echolocation]], a skill they share with [[dolphin]]s and [[whale]]s. But although the eyes of most species of microbats are small and poorly developed, the sense of vision is still functional, especially at long distances, beyond the range of echolocation. Their senses of smell and hearing, however, are excellent. A few moths have exploited the bat's senses; in one group (the [[Arctiidae|tiger moths]]), the moths produce [[ultrasonic]] signals to warn the bats that the moths are chemically-protected ([[aposematism]]) (this was once thought to be a form of "[[radar jamming]]", but this theory has been disproved); in the other group ([[Noctuidae]]) the moths have a type of hearing organ called a [[tympanum]] which responds to an incoming bat signal by causing the moth's flight muscles to twitch erratically, sending the moth into random evasive maneuvers.
+
==Size==
 +
[[Image:Golden crowned fruit bat.jpg|thumb|left|Giant golden-crowned flying fox, ''Acerodon jubatus,'' the largest bat]]
 +
Most bats are very small for mammals. The smallest bat (also the smallest mammal) is the bumblebee bat, or Kitti's hog-nosed bat, of [[Thailand]] ''(Craseonycteris thonglongyai),'' which weighs only two grams (0.07 oz). The largest bat is the giant golden-crowned flying fox of the Philippines ''(Acerodon jubatus),'' which weighs 1500 grams (3.3 lbs) and has a wingspan of about 1.7 meters (5.5 feet). The largest bat in [[Canada]] is the hoary bat ''(Lasiurus cinereus),'' which weighs about 30 grams (0.9 oz). It could be sent through the mail with one first class Canadian postage stamp (Fenton 1998, Voelker 1986).
  
The teeth of microbats resemble those of the [[insectivora]]ns. They are very sharp in order to bite through the [[sclerotization|hardened]] armour of insects or the skin of fruits.
+
==Flight==
  
Megabats are primarily fruit- or nectar-eating. They have, however, probably evolved for some time in New Guinea without microbat concurrention. This has resulted in some smaller megabats of the genus ''[[Nyctimene]]'' becoming (partly) insectivorous to fill the vacant microbat ecological niche. Furthermore, there is some evidence that the fruit bat genus ''[[Pteralopex]]'', which occurs in the [[Solomon Islands]], and its close relative ''[[Mirimiri]]'' from [[Fiji]], have evolved to fill some niches that were open because there are no nonvolant mammals in those islands.
+
Bats fly with a swimming-like motion in which they grab pockets of air with their hand membranes. The fastest bat is the Mexican free-tailed bat ''(Tadarida brasiliensis),'' which can reach speeds of 40 mph in level flight and 80 mph in dives (65 and 130 kph). It has also been known to fly as high as 3,000 meters (10,000 feet) to take advantage of high-altitude winds. Many bats can hover, like [[hummingbird]]s, in order to pick insects off surfaces or to feed from flowers (Voelker 1986).
  
While other mammals have one-way valves only in their [[vein]]s to prevent the blood from flowing backwards, bats also have the same mechanism in their [[artery|arteries]].
+
Because their [[wing]]s are much thinner than those of birds, bats can maneuver more quickly and more precisely than [[bird]]s. The surface of their wings are also equipped with touch-sensitive receptors on small bumps called [[Merkel cell]]s, found in most mammals, including humans. But these sensitive areas are different in bats as each bump has a tiny hair in the center, making it even more sensitive, and allowing the bat to detect and collect information about the air flowing over its wings. An additional kind of receptor cell is found in the wing membrane of species that use their wings to catch prey. This receptor cell is sensitive to the stretching of the membrane. The cells are concentrated in areas of the membrane where insects hit the wings when the bats capture them (Calhoun 2005).
  
The finger bones of a bat are much more flexible than those of other mammals. One reason is that the cartilage in their fingers lacks calcium and other minerals nearer the tips, increasing their ability to bend without splintering. The cross section of the finger bone is also flattened instead of circular as is the bone in a human finger, making it even more flexible. The skin on their wing membranes is a lot more elastic and can stretch much more than what is usually seen among mammals.
+
Bat flight requires a great deal of energy. To power its flight muscles a typical bat's heart rate increases from 300 to 1000 beats per minute when it flies. In order to keep active bats need a good supply of high-energy food at least every few days. In places where this is not possible, many bats are [[Dormancy|dormant]] in winter to save energy (Richardson 2002).
  
Because their wings are much thinner than those of birds, bats can maneuver more quickly and more precisely than birds. The surface of their wings are also equipped with touch-sensitive receptors on small bumbs called "Merkel cells", which is found in most mammals, including humans. But these sensitive areas are different in bats as there are a tiny hair in the center, making it even more sensitive and detects and collects information about the air flowing over the wings. Another kind of receptor cells are found in the wing membrane in species who are using their wings to catch prey, and is sensitive to the stretching of the membrane. These cells are concentrated in the areas of the membrane where insects hits the wings when the bats captures them. Bats are not blind.
+
==Diet==
 +
Most microbats depend on a diet of [[insect]]s. These are most often caught in the air while flying, although some bats capture insects on the ground or from plants. Some of the larger microbats eat larger animals such as [[fish]], [[frog]]s, [[mice]], small [[bird]]s, or even other bats. In the New World where megabats are absent, some microbats have taken to diets of fruit or nectar. The vampire bat of South America ''(Desmodus rotundus)'' drinks the blood of living animals.  
  
[http://www.fladdermus.net/thesis.htm More about microbat vision]
+
Most megabats have diet of [[fruit]], while some drink the nectar of flowers. Megabats play an important role in both pollinating plants and in dispersing their seeds. Only the juice of the fruit is eaten while the seeds pass quickly through the digestive system, or are not eaten in the first place but only dropped to the ground. The very survival of some jungle trees depends on the megabats.  
  
== Reproduction ==
+
Insect-eating bats also play an important role in controlling insect populations (Richardson 2002).
[[Image:Myotis myotis, nursery roost.jpg|thumb|Colony of [[Mouse-eared Bat]]s, ''Myotis myotis''.]]
 
Mother bats usually have only one offspring per year. A baby bat is referred to as a pup. Pups are usually left in the roost when they are not nursing. However, a newborn bat can cling to the fur of the mother like pouch and be transported, although they soon grow too large for this. It would be difficult for an adult bat to carry more than one young, but normally only one young is born. Bats often form [[nursery roost]]s, with many females giving birth in the same area, be it a cave, a tree hole, or a cavity in a building. Mother bats are able to find their young in huge colonies of millions of other pups. Pups have even been seen to feed on other mothers' milk if their mother is dry. Only the mother cares for the young, and there is no continuous partnership with male bats.
 
  
The ability to fly is congenital, but after birth the wings are too small to fly. Young [[microbat]]s become independent at the age of 6 to 8 weeks, [[megabat]]s not until they are four months old. At the age of two years bats are sexually mature.
+
==Echolocation==
 +
While true flight is unique to bats among mammals, echolocation is not. For example, some [[cetacean]]s, [[bird]]s, and [[shrew]]s are known to echolocate. Furthermore, not all bats echolocate, although it is quite common among the microbats (and ''Rousettus'' and relatives among the megabats.)
  
==Habits and behavior==
+
By emitting high-pitched sounds and listening to the [[echo (phenomenon)|echoes]], also known as sonar, microbats locate prey and other nearby objects. This is the process of echolocation. While some macrobats also use echolocation, the sounds are produced by tongue clicks and are used to find their way in caves and other dark places not to find food.
[[Image:Yaxchilan_labyrinth_bats.jpg|thumb|Bats in a cave at the [[Yaxchilan]] ruins in Chiapas, Mexico.]]
 
Bats vary in social structure, with some bats leading a solitary life and others living in caves colonized by more than a million bats.
 
  
The fission-fusion social structure is seen among several species of bats. The fusion part is all the individuals in a roosting area. The fission part is the breaking apart and mixing of subgroups by switching roosts with bats, ending up with bats in different trees and often with different roostmates.
+
Echolocating microbats produce short bursts of sound, up to 200 per second. The sounds typically are too high pitched for humans to hear but are extremely loud, up to 110 decibels. (Many species utilize sounds within the range of human [[hearing (sense)|hearing]].) By using echolocation, microbats can detect flying insects and avoid obstacles to their flight, even in total darkness. The external ears of most microbats are very large for their size and are often shaped and folded in complex ways to enhance their reception of echolocation signals. Some bats also have a "noseleaf," a structure on the nose that is involved in echolocation (Fenton 1998, Voelker 1986).
  
Studies also show that bats make all kinds of sounds to communicate with each other. Scientists in the field have listened to bats and have been able to identify some sounds with some behavior bats will make right after the sounds are made.
+
Two groups of [[moth]]s exploit the bats' senses. Tiger moths produce ultrasonic signals to warn the bats that the moths are chemically-protected (aposematism) (this was once thought to be a form of "radar jamming," but this theory has been disproved). The moths Noctuidae have a hearing organ called a tympanum that responds to an incoming bat signal by causing the moth's flight muscles to twitch erratically, sending the moth into random evasive maneuvers.
  
== Vectors for pathogens ==
+
==Roosting==
Bats are natural reservoirs or [[vector (biology)|vector]]s for a large number of [[zoonosis|zoonotic]] [[pathogen]]s including [[rabies]], [[SARS]], [[Nipah virus]], [[West Nile virus]] and possibly [[ebola virus]]. Their high mobility, broad distribution, social behaviour (communal roosting, fission-fusion social structure) and close evolutionary relationship to humans make bats favourable hosts and disseminators of disease. Many species also appear to have a high tolerance for habouring pathogens and often do not develop disease while infected.
 
  
[[image:bat-capture-moth1nov2000_hi.jpg|thumb|A [[big brown bat]] (''Eptesicus fuscus'') approaches a [[wax moth]] (''Galleria mellonella''), which serves as the control species for the studies of the [[tiger moth]]s. The moth is only "semi-tethered," allowing it the mobility to fly evasively.]]
+
Almost all bats are active at night and rest during the day. Most bats hang head down from their hind feet while resting. It is vital for them to have roosting places where they are hidden from predators and that have proper temperature and humidity. Bats can quickly become dehydrated because of water loss through their wing membranes. (This might also be one reason that they fly at night.) Many bats roost in caves where they can find constant conditions and where predators can not reach them. One of the largest groups of bats was found in a cave in Arizona and contained 25 to 50 million Mexican free-tailed bats. Many megabats roost hanging from [[tree]] branches. Other bats roost in hollow trees or clinging to the sides of trees. Some rest in rolled up leaves or inside the stems of [[bamboo]] (Voelker 1986; Schober 1984).
 +
[[Image:wiki bat.jpg|thumb|left|Thermographic image of a bat using trapped air as insulation.]]
 +
Human activity has sometimes taken away bat roosting sites, for instance when old dead trees are cut down. Human visits to caves can also disturb bats. This can be especially harmful when it awakens them from hibernation and they have to spend precious energy finding new roosting places. On the other hand, bats have taken advantage of buildings for roosting sites. As people have become more interested in bat conservation measures have been taken to protect their roosting places. This can include excluding humans from roosting caves and providing bat boxes and even bat towers for alternative roosting sites (Schober 1984; Richardson 2002). A bat house constructed in 1991 at the University of Florida campus next to Lake Alice in Gainesville has a population of over 100,000 free-tailed bats (Nordlie 2001).
  
''The following advice is only relevant to areas with endemic rabies.''
+
== Reproduction ==
 +
[[Image:Myotis myotis, nursery roost.jpg|thumb|Nursery roost of mouse-eared bats, ''Myotis myotis'']]
 +
Mother bats usually have only one offspring per year. A baby bat is referred to as a [[pup]].
  
Only 0.5% of bats carry rabies. However, of the very few cases of [[rabies]] reported in the United States every year, most are caused by bat [[bite (medicine)|bites]]. Although most bats do not have rabies, those that do may be clumsy, disoriented, and unable to fly, which makes it more likely that they will come into contact with humans. Although one should not have an unreasonable fear of bats, one should avoid handling them or having them in one's living space, as with any wild animal. If a bat is found in living quarters near a child, mentally handicapped person, intoxicated person, sleeping person, or pet, the person or pet should receive immediate medical attention for rabies. Bats have very small teeth and can bite a sleeping person without necessarily being felt.  
+
Pups are usually left in the roost when they are not [[breastfeeding|nursing]]. However, a newborn bat can cling to the [[fur]] of the mother and be transported, although they soon grow too large for this. It would be difficult for an adult bat to carry more than one young, but normally only one young is born.  
  
If a bat is found in a house and the possibility of exposure cannot be ruled out, the bat should be sequestered and an animal control officer called immediately, so that the bat can be analyzed. This also applies if the bat is found dead. If it is certain that nobody has been exposed to the bat, it should be removed from the house. The best way to do this is to close all the doors and windows to the room except one to the outside. The bat should soon leave.  
+
Bats often form nursery roosts, with many females giving birth in the same area, be it a [[cave]], a tree hole, or a cavity in a building. Mother bats are able to find their young in huge colonies of millions of other pups. Pups have even been seen to feed on other mothers' milk if their mother is dry. Only the mother cares for the young, and there is no continuous partnership with male bats.  
  
Due to the risk of rabies and also due to health problems related to their [[guano]], bats should be excluded from inhabited parts of houses. For full detailed information on all aspects of bat management, including how to capture a bat, what to do in case of exposure, and how to bat-proof a house humanely, see [http://www.cdc.gov/ncidod/dvrd/rabies/Bats_&_Rabies/bats&.htm the Centers for Disease Control's website on bats and rabies]. In certain countries, such as the UK, it is illegal to handle bats without a license.
+
The ability to fly is congenital, but at birth the wings are too small to fly. Young microbats become independent at the age of six to eight weeks, megabats not until they are four months old. At the age of two years, most bats are sexually mature. A single bat can live over 20 years, but the bat population growth is limited by the slow [[birth rate]].
  
Where rabies is not endemic, as throughout most of western Europe, small bats can be considered as harmless. Larger bats can give a nasty bite.  Treat them with the respect due to any wild animal.
+
==Classification==
 
+
[[Image:Vespertilio murinus.jpg|thumb|Parti-colored bat, ''Vespertilio murinus'']]  
==Cultural aspects==
+
[[Image:Pipistrellus pipistrellus01.jpg|thumb|Common pipistrelle, ''Pipistrellus pipistrellus'']]
The bat is sacred in [[Tonga]] and [[West Africa]] and is often considered the physical manifestation of a separable [[soul]]. Bats are closely associated with [[vampire]]s, who are said to be able to [[shapeshifting|shapeshift]] into bats, [[fog]] or [[wolf|wolves]].  Bats are also a symbol of [[ghost]]s, [[death]] and [[disease]]. Among some [[Native Americans in the United States|Native Americans]], such as the [[Creek (people)|Creek]], [[Cherokee]] and [[Apache Tribe|Apache]], the bat is a [[trickster]] spirit. [[China|Chinese]] lore claims the bat is a symbol of longevity and happiness, and is similarly lucky in [[Poland]] and geographical [[Macedonia (region)|Macedonia]] and among the [[Kwakiutl]] and [[Arab]]s.  
+
   
 
+
*'''ORDER CHIROPTERA''' (Ky-rop`ter-a) (Gr. ''cheir,'' hand, + ''pteron,'' wing)
In Western Culture, the bat is often a symbol of the night and its foreboding nature. The bat is a primary animal associated with fictional characters of the night such as both [[villain]]s like [[Dracula]] and [[hero]]es like [[Batman]].  The association of the fear of the night with the animal was treated as a literary challenge by [[Kenneth Oppel]], who created a best selling series of novels, beginning with ''[[Silverwing (novel)|Silverwing]]'', which feature bats as the central heroic figures much in a similar manner as the classic [[novel]] ''[[Watership Down]]'' did for [[rabbit]]s. An old wives' tale has it that bats will entangle themselves in people's hair. A likely root to this myth is that insect-eating bats seeking prey may dive erratically toward people, who attract mosquitoes and gnats, leading the squeamish to believe that the bats are trying to get in their hair.
+
**'''Suborder Megachiroptera (megabats)'''
 
+
*** Pteropodidae
In the [[United Kingdom]] all bats are protected under the [[Wildlife and Countryside Act]]s, and even disturbing a bat or its roost can be punished with a heavy fine.
+
**'''Suborder Microchiroptera (microbats)'''
 +
*** Superfamily Emballonuroidea
 +
**** Emballonuridae (Sac-winged or Sheath-tailed bats)
 +
*** Superfamily Molossoidea
 +
**** Antrozoidae (Pallid bats)
 +
**** Molossidae (Free-tailed bats)
 +
*** Superfamily Nataloidea
 +
**** Furipteridae (Smoky bats)
 +
**** Myzopodidae (Sucker-footed bats)
 +
**** Natalidae (Funnel-eared bats)
 +
**** Thyropteridae (Disk-winged bats)
 +
*** Superfamily Noctilionoidea
 +
**** Mormoopidae (Ghost-faced or Moustached bats)
 +
**** Mystacinidae (New Zealand short-tailed bats)
 +
**** Noctilionidae (Bulldog bats or Fisherman bats)
 +
**** Phyllostomidae (Leaf-nosed bats)
 +
*** Superfamily Rhinolophoidea
 +
**** Megadermatidae (False vampires)
 +
**** Nycteridae (Hollow-faced or Slit-faced bats)
 +
**** Rhinolophidae (Horseshoe bats)
 +
*** Superfamily Rhinopomatoidea
 +
**** Craseonycteridae (Bumblebee Bat or Kitti's Hog-nosed Bat)
 +
**** Rhinopomatidae (Mouse-tailed bats)
 +
*** Superfamily Vespertilionoidea
 +
**** Vespertilionidae (Vesper bats or Evening bats)
  
[[Austin, Texas]] is the summer home to North America's largest urban bat colony, an estimated 1,500,000 [[Mexican free-tailed bat]]s, who eat an estimated 10,000 to 30,000 pounds of insects each night and attract 100,000 tourists each year.
+
==Bats and humans==
 +
There is little direct interaction between bats and humans, although humans greatly benefit from the bats' role in controlling [[insect]] pests, especially night-flying [[mosquito]]s, which can be carriers of [[malaria]] and other serious diseases. No bat species has ever been domesticated, or even kept as a pet. Because of their small size, bats are not generally considered a food resource for humans, although in some places the larger megabats are caught and eaten. Bat droppings, or guano, are harvested from caves where bats roost for use as fertilizer (Schober 1984).  
  
===References===
+
Major negative impacts of bats on human interests are confined to the vampire bat, which causes serious problems by spreading [[rabies]] to humans and domestic animals, and to some of the megabats, which prey on fruit crops. Other bats can also carry rabies but do not often spread the disease by biting humans. Rabies also can be contracted by contact with bat urine. Care must be taken in visiting bat roosting sites and in handling live bats (Fenton 1998).
*Greenhall, Arthur H. 1961. ''Bats in Agriculture''. A Ministry of Agriculture Publication. Trinidad and Tobago.
+
[[Image:Dsg UF Bat House 20050507.jpg|thumb|right|University of Florida bat house]]
*Nowak, Ronald M. 1994. " Walker's BATS of the World". The John Hopikins University Press, Baltimore and London.
+
Some bat species are now endangered because of destruction of their habitats, while others have benefited by human activities such as clearing of forests, damming of streams, and construction, which can give them more hunting and roosting space. In Austin, Texas, the Congress Avenue bridge is the summer home to [[North America]]'s largest urban bat colony, an estimated 1,500,000 Mexican free-tailed bats, who eat an estimated 10,000 to 30,000 pounds of insects each night and attract 100,000 tourists each year.
*[http://www.uq.edu.au/nuq/jack/consensus.htm John D. Pettigrew's summary on Flying Primate Hypothesis]
 
  
== See also ==
+
Bats have figured in human culture and imagination. In the West, they have often been associated with evil, such as witches, vampires, or the devil. In China, however, they are considered a sign of good fortune and the word ''"fu"'' means both "bat" and "happiness" (Schober 1984).
*[[European Bat Night]]
 
*[[Bat bomb]]
 
*[[Batman]]
 
*[[Bat World Sanctuary]]
 
*[[:Category:Fictional bats|Fictional bats]]
 
  
== External links ==
+
With humankind's increasing concern over the natural world, bats have become more appreciated and efforts are being made for their preservation, including laws protecting them in many countries. In the [[United Kingdom]], all bats are protected under the Wildlife and Countryside Acts, and even disturbing a bat or its roost can be punished with a heavy fine. In Sarawak, [[Malaysia]], bats are protected species under the Wildlife Protection Ordinance 1998.
*[http://www.awf.org/wildlives/62#news Bats: Wildlife summary from the African Wildlife Foundation]
 
  
{{sisterlinks|bat}}
+
==References==
{{Wikibookspar|Dichotomous Key|Chiroptera}}
+
*Calhoun, M. 2005. [http://news.research.ohiou.edu/news/index.php?item=257 "Bats use touch receptors on wings to fly, catch prey, study finds"]. Ohio University. Retrieved September 3, 2007.
*[http://www.abrn.blogspot.com Arkansas Bat Rescue Network]
+
*Fenton, M. 1998. ''The Bat: Wings in the Night Sky.'' Buffalo, NY: Firefly Press. ISBN 1552092534
*[http://www.batworld.org/local_rescue/local_rescue.html United States Bat Rescue]
+
*Nordlie, T. 2001. "Backyard bat houses promote pest control, says UF expert." ''UF News'' October 29, 2001. University of Florida.  
*[http://www.batcon.org Bat Conservation International website]
+
*Richardson, P. 2002. ''Bats.'' Washington, DC: Smithsonian Intitution Press. ISBN 1588340201
*[http://www.batworld.org Bat World Sanctuary]
+
*Schober, W. 1984. ''The Lives of Bats.'' New York: Arco Publishing, Inc. ISBN 0668059931
*[http://www.nsrl.ttu.edu/tmot1/ordchiro.htm Texas Parks and Wildlife Bat Page] 
+
*Voelker, W. 1986. ''The Natural History of Living Mammals.'' Medford, NJ: Plexus Publishing. ISBN 0937548081
*[http://animaldiversity.ummz.umich.edu/chordata/mammalia/chiroptera.html University of Michigan Museum of Zoology]
 
*[http://tolweb.org/tree?group=Chiroptera&contgroup=Eutheria Tree of Life]
 
*[http://flyingfur.typepad.com/ Flying Fur]
 
*[http://news.bbc.co.uk/2/hi/science/nature/4213495.stm Bats make up 20% of mammals]
 
*[http://www.bats.org.uk The Bat Conservation Trust]
 
*[http://www.batworld.org/adopt_a_bat/adopt_a_bat.html Adopt-a-Bat]
 
*[http://www.batconservation.org Organization for Bat Conservation]
 
*[http://www.uni-tuebingen.de/tierphys/Kontakt/mitarbeiter_seiten/dietz.htm Illustrated Identification key to the (micro)bats of Europe]  (''see "Recent publications"'')
 
*[http://www.lubee.org Lubee Bat Conservancy]
 
*[http://www.morcegolivre.vet.br Bats from Brazil]
 
*[http://nssmembersforum.proboards28.com/index.cgi U.S. Cavers Forum - Bats]
 
*[http://rainforest.montclair.edu/pwebrf/rainforest/Animals/mammals/bats.html General text on bats]
 
  
  
 
{{Mammals}}
 
{{Mammals}}
  
{{credit|60831028}}
+
{{credit|Bat|151517605}}
 
+
[[Category:Life sciences]][[Category:Animals]][[Category:Mammals]]
 
 
 
 
[[Category:Life sciences]]
 

Latest revision as of 14:45, 28 July 2019

Bats
Fossil range: Late Paleocene - Recent
Townsend's Big-eared Bat, Corynorhinus townsendii
Townsend's Big-eared Bat, Corynorhinus townsendii
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Eutheria
Superorder: Laurasiatheria
Order: Chiroptera
Blumenbach, 1779
Suborders

Megachiroptera
Microchiroptera
See text for families.

A bat is a mammal in the order Chiroptera. Their most distinguishing feature is that their forelimbs are developed as wings, making them the only mammals in the world naturally capable of flight. (Other mammals, such as flying squirrels, lemurs, and flying opossums, can glide for limited distances). There are estimated to be about 1,100 species of bats worldwide, accounting for about 20 percent of all mammal species (Trudge 2000).

Though sometimes called "flying rodents," "flying mice," or even mistaken for insects and birds, bats are not, in fact, rodents.

While in China bats are considered a sign of good fortune, in the West they often are viewed negatively, such as associated with witches or vampires. Some bat-human interactions indeed are unfavorable for humans, such as those fruit-eating bats that compete for crops and the blood consuming vampire bats that can spread rabies to humans and domestic animals. But bats as a group provide important benefits to the ecosystem and to humans. Some of the smaller bat species are important pollinators of some tropical flowers. Indeed, many tropical plants are now found to be totally dependent on them, not just for pollination, but for spreading their seeds by eating the resulting fruits. Insect-eating bats also play an important role in controlling insect populations, including night-flying mosquitos that might be carriers of malaria and other serious diseases. Some of the larger bats are a food source, and bat droppings, or guano, are harvested for use as fertilizer.

Given the ability of fruit-eating bats to spread seeds, there are environmental concerns when a bat is introduced in a new setting. Tenerife provides a recent example with the introduction of the Egyptian fruit bat.

The word Chiroptera can be translated from the Greek words for "hand wing," as the structure of the open wing is very similar to an outspread human hand with a membrane (patagium) between the fingers that also stretches between hand and body.

Megabats versus microbats

Bats are divided into two distinct groups (or suborders):

  • Megachiroptera (megabats)
  • Microchiroptera (microbats/echolocating bats)

Despite the name, not all megabats are larger than microbats. The major distinction between the two suborders is based on other factors:

  • Microbats use echolocation, whereas megabats do not (except for Rousettus and relatives, which do).
  • Microbats lack the claw at the second toe of the forelimb.
  • The ears of microbats do not form a closed ring, but the edges are separated from each other at the base of the ear.
  • Microbats lack underfur; they have only guard hairs or are naked.

Megabats are found in Africa and Asia. They eat fruit, nectar or pollen, with some supplementing their diets with a few insects. Some megabat species are known as flying foxes. There are about 170 species of megabats. Microbats are found on all continents except Antarctica. Most of them eat insects, while a few eat fruit, nectar, or small animals, or drink the blood of large animals. There are about 800 species of microbats (Richardson 2002).

Size

Giant golden-crowned flying fox, Acerodon jubatus, the largest bat

Most bats are very small for mammals. The smallest bat (also the smallest mammal) is the bumblebee bat, or Kitti's hog-nosed bat, of Thailand (Craseonycteris thonglongyai), which weighs only two grams (0.07 oz). The largest bat is the giant golden-crowned flying fox of the Philippines (Acerodon jubatus), which weighs 1500 grams (3.3 lbs) and has a wingspan of about 1.7 meters (5.5 feet). The largest bat in Canada is the hoary bat (Lasiurus cinereus), which weighs about 30 grams (0.9 oz). It could be sent through the mail with one first class Canadian postage stamp (Fenton 1998, Voelker 1986).

Flight

Bats fly with a swimming-like motion in which they grab pockets of air with their hand membranes. The fastest bat is the Mexican free-tailed bat (Tadarida brasiliensis), which can reach speeds of 40 mph in level flight and 80 mph in dives (65 and 130 kph). It has also been known to fly as high as 3,000 meters (10,000 feet) to take advantage of high-altitude winds. Many bats can hover, like hummingbirds, in order to pick insects off surfaces or to feed from flowers (Voelker 1986).

Because their wings are much thinner than those of birds, bats can maneuver more quickly and more precisely than birds. The surface of their wings are also equipped with touch-sensitive receptors on small bumps called Merkel cells, found in most mammals, including humans. But these sensitive areas are different in bats as each bump has a tiny hair in the center, making it even more sensitive, and allowing the bat to detect and collect information about the air flowing over its wings. An additional kind of receptor cell is found in the wing membrane of species that use their wings to catch prey. This receptor cell is sensitive to the stretching of the membrane. The cells are concentrated in areas of the membrane where insects hit the wings when the bats capture them (Calhoun 2005).

Bat flight requires a great deal of energy. To power its flight muscles a typical bat's heart rate increases from 300 to 1000 beats per minute when it flies. In order to keep active bats need a good supply of high-energy food at least every few days. In places where this is not possible, many bats are dormant in winter to save energy (Richardson 2002).

Diet

Most microbats depend on a diet of insects. These are most often caught in the air while flying, although some bats capture insects on the ground or from plants. Some of the larger microbats eat larger animals such as fish, frogs, mice, small birds, or even other bats. In the New World where megabats are absent, some microbats have taken to diets of fruit or nectar. The vampire bat of South America (Desmodus rotundus) drinks the blood of living animals.

Most megabats have diet of fruit, while some drink the nectar of flowers. Megabats play an important role in both pollinating plants and in dispersing their seeds. Only the juice of the fruit is eaten while the seeds pass quickly through the digestive system, or are not eaten in the first place but only dropped to the ground. The very survival of some jungle trees depends on the megabats.

Insect-eating bats also play an important role in controlling insect populations (Richardson 2002).

Echolocation

While true flight is unique to bats among mammals, echolocation is not. For example, some cetaceans, birds, and shrews are known to echolocate. Furthermore, not all bats echolocate, although it is quite common among the microbats (and Rousettus and relatives among the megabats.)

By emitting high-pitched sounds and listening to the echoes, also known as sonar, microbats locate prey and other nearby objects. This is the process of echolocation. While some macrobats also use echolocation, the sounds are produced by tongue clicks and are used to find their way in caves and other dark places not to find food.

Echolocating microbats produce short bursts of sound, up to 200 per second. The sounds typically are too high pitched for humans to hear but are extremely loud, up to 110 decibels. (Many species utilize sounds within the range of human hearing.) By using echolocation, microbats can detect flying insects and avoid obstacles to their flight, even in total darkness. The external ears of most microbats are very large for their size and are often shaped and folded in complex ways to enhance their reception of echolocation signals. Some bats also have a "noseleaf," a structure on the nose that is involved in echolocation (Fenton 1998, Voelker 1986).

Two groups of moths exploit the bats' senses. Tiger moths produce ultrasonic signals to warn the bats that the moths are chemically-protected (aposematism) (this was once thought to be a form of "radar jamming," but this theory has been disproved). The moths Noctuidae have a hearing organ called a tympanum that responds to an incoming bat signal by causing the moth's flight muscles to twitch erratically, sending the moth into random evasive maneuvers.

Roosting

Almost all bats are active at night and rest during the day. Most bats hang head down from their hind feet while resting. It is vital for them to have roosting places where they are hidden from predators and that have proper temperature and humidity. Bats can quickly become dehydrated because of water loss through their wing membranes. (This might also be one reason that they fly at night.) Many bats roost in caves where they can find constant conditions and where predators can not reach them. One of the largest groups of bats was found in a cave in Arizona and contained 25 to 50 million Mexican free-tailed bats. Many megabats roost hanging from tree branches. Other bats roost in hollow trees or clinging to the sides of trees. Some rest in rolled up leaves or inside the stems of bamboo (Voelker 1986; Schober 1984).

Thermographic image of a bat using trapped air as insulation.

Human activity has sometimes taken away bat roosting sites, for instance when old dead trees are cut down. Human visits to caves can also disturb bats. This can be especially harmful when it awakens them from hibernation and they have to spend precious energy finding new roosting places. On the other hand, bats have taken advantage of buildings for roosting sites. As people have become more interested in bat conservation measures have been taken to protect their roosting places. This can include excluding humans from roosting caves and providing bat boxes and even bat towers for alternative roosting sites (Schober 1984; Richardson 2002). A bat house constructed in 1991 at the University of Florida campus next to Lake Alice in Gainesville has a population of over 100,000 free-tailed bats (Nordlie 2001).

Reproduction

Nursery roost of mouse-eared bats, Myotis myotis

Mother bats usually have only one offspring per year. A baby bat is referred to as a pup.

Pups are usually left in the roost when they are not nursing. However, a newborn bat can cling to the fur of the mother and be transported, although they soon grow too large for this. It would be difficult for an adult bat to carry more than one young, but normally only one young is born.

Bats often form nursery roosts, with many females giving birth in the same area, be it a cave, a tree hole, or a cavity in a building. Mother bats are able to find their young in huge colonies of millions of other pups. Pups have even been seen to feed on other mothers' milk if their mother is dry. Only the mother cares for the young, and there is no continuous partnership with male bats.

The ability to fly is congenital, but at birth the wings are too small to fly. Young microbats become independent at the age of six to eight weeks, megabats not until they are four months old. At the age of two years, most bats are sexually mature. A single bat can live over 20 years, but the bat population growth is limited by the slow birth rate.

Classification

Parti-colored bat, Vespertilio murinus
Common pipistrelle, Pipistrellus pipistrellus
  • ORDER CHIROPTERA (Ky-rop`ter-a) (Gr. cheir, hand, + pteron, wing)
    • Suborder Megachiroptera (megabats)
      • Pteropodidae
    • Suborder Microchiroptera (microbats)
      • Superfamily Emballonuroidea
        • Emballonuridae (Sac-winged or Sheath-tailed bats)
      • Superfamily Molossoidea
        • Antrozoidae (Pallid bats)
        • Molossidae (Free-tailed bats)
      • Superfamily Nataloidea
        • Furipteridae (Smoky bats)
        • Myzopodidae (Sucker-footed bats)
        • Natalidae (Funnel-eared bats)
        • Thyropteridae (Disk-winged bats)
      • Superfamily Noctilionoidea
        • Mormoopidae (Ghost-faced or Moustached bats)
        • Mystacinidae (New Zealand short-tailed bats)
        • Noctilionidae (Bulldog bats or Fisherman bats)
        • Phyllostomidae (Leaf-nosed bats)
      • Superfamily Rhinolophoidea
        • Megadermatidae (False vampires)
        • Nycteridae (Hollow-faced or Slit-faced bats)
        • Rhinolophidae (Horseshoe bats)
      • Superfamily Rhinopomatoidea
        • Craseonycteridae (Bumblebee Bat or Kitti's Hog-nosed Bat)
        • Rhinopomatidae (Mouse-tailed bats)
      • Superfamily Vespertilionoidea
        • Vespertilionidae (Vesper bats or Evening bats)

Bats and humans

There is little direct interaction between bats and humans, although humans greatly benefit from the bats' role in controlling insect pests, especially night-flying mosquitos, which can be carriers of malaria and other serious diseases. No bat species has ever been domesticated, or even kept as a pet. Because of their small size, bats are not generally considered a food resource for humans, although in some places the larger megabats are caught and eaten. Bat droppings, or guano, are harvested from caves where bats roost for use as fertilizer (Schober 1984).

Major negative impacts of bats on human interests are confined to the vampire bat, which causes serious problems by spreading rabies to humans and domestic animals, and to some of the megabats, which prey on fruit crops. Other bats can also carry rabies but do not often spread the disease by biting humans. Rabies also can be contracted by contact with bat urine. Care must be taken in visiting bat roosting sites and in handling live bats (Fenton 1998).

University of Florida bat house

Some bat species are now endangered because of destruction of their habitats, while others have benefited by human activities such as clearing of forests, damming of streams, and construction, which can give them more hunting and roosting space. In Austin, Texas, the Congress Avenue bridge is the summer home to North America's largest urban bat colony, an estimated 1,500,000 Mexican free-tailed bats, who eat an estimated 10,000 to 30,000 pounds of insects each night and attract 100,000 tourists each year.

Bats have figured in human culture and imagination. In the West, they have often been associated with evil, such as witches, vampires, or the devil. In China, however, they are considered a sign of good fortune and the word "fu" means both "bat" and "happiness" (Schober 1984).

With humankind's increasing concern over the natural world, bats have become more appreciated and efforts are being made for their preservation, including laws protecting them in many countries. In the United Kingdom, all bats are protected under the Wildlife and Countryside Acts, and even disturbing a bat or its roost can be punished with a heavy fine. In Sarawak, Malaysia, bats are protected species under the Wildlife Protection Ordinance 1998.

References
ISBN links support NWE through referral fees


Mammals
Monotremata (platypus, echidnas)

Marsupialia: | Paucituberculata (shrew opossums) | Didelphimorphia (opossums) | Microbiotheria | Notoryctemorphia (marsupial moles) | Dasyuromorphia (quolls and dunnarts) | Peramelemorphia (bilbies, bandicoots) | Diprotodontia (kangaroos and relatives)

Placentalia: Cingulata (armadillos) | Pilosa (anteaters, sloths) | Afrosoricida (tenrecs, golden moles) | Macroscelidea (elephant shrews) | Tubulidentata (aardvark) | Hyracoidea (hyraxes) | Proboscidea (elephants) | Sirenia (dugongs, manatees) | Soricomorpha (shrews, moles) | Erinaceomorpha (hedgehogs and relatives) Chiroptera (bats) | Pholidota (pangolins)| Carnivora | Perissodactyla (odd-toed ungulates) | Artiodactyla (even-toed ungulates) | Cetacea (whales, dolphins) | Rodentia (rodents) | Lagomorpha (rabbits and relatives) | Scandentia (treeshrews) | Dermoptera (colugos) | Primates |

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

The history of this article since it was imported to New World Encyclopedia:

Note: Some restrictions may apply to use of individual images which are separately licensed.