bat(redirected from Bat life expectancy)
Also found in: Dictionary, Thesaurus, Medical, Legal.
bat,winged mammal of the order Chiroptera, which includes 900–1,000 species classified in about 200 genera and 17 families. Bats range in size from a wingspread of over 5 ft (150 cm) to a wingspread of less than 2 in. (5 cm). They are found in nearly all parts of the world but are most numerous in the tropics; there are about 39 species in the United States. Most bats are economically valuable because of the large number of insects they consume.
The body of the bat is mouselike and usually covered with fine fur. The face varies greatly from one species to another; many species have complex appendages on the snout and projections, or false ears, in front of the true ears; the ears themselves are often very large and elaborately convoluted. These facial structures are part of the sensory apparatus that emits and receives sound vibrations.
Some bats are solitary, living in caves, crevices, hollow trees, or attics; other species are communal, with thousands or even millions of bats roosting together in a cave or on branches in a section of forest. In some species of communal bats, the entire colony leaves the roost together in the evening and returns together in the morning; in others, individuals come and go at different times. Bats of northern regions migrate, hibernate, or both in winter.
In most species, males and females do not associate except during the mating season. Females of most species bear a single young in the summer of each year. The young are then carried by the mothers for a few days, after which they are left in the roost when not nursing; they begin to fly in a few weeks. The life span of some bats is 20 years in captivity.
Bats are the only mammals capable of true flight, that is, flight powered by muscular movement as distinct from gliding. The wing is a double membrane of skin stretched between the enormously elongated bones of four fingers and extending along the body from the forelimbs to the hind limbs and from there to the tail. The thumb is small, clawed, and free from the membrane. The hind limbs are small and may be rotated in such a way that the knees bend backward rather than forward, as in other mammals; this is presumably an adaptation for takeoff and flight. Bats at rest hang head down, grasping a twig or crevice with their clawed feet; they take off into flight from this position.
Nearly all bats are nocturnal and many live in caves; although they see well, they rely primarily on their highly developed hearing, using echolocation (sonar) to avoid collisions and to capture insects in flight. The bat emits high-pitched sounds (up to 100,000 hertz) that echo from objects it encounters; the echo provides the bat with information about the size, shape, and distance of the object. The rate at which bats emit these squeaks is sometimes as high as 200 per second. Blinded bats easily find their way through complex obstacle courses, but deafness leaves them helpless.
Types of Bats
The bat order is divided on anatomical grounds into two major divisions, or suborders: the Megachiroptera, or fruit batsfruit bat,
fruit-eating bat found in tropical regions of the Old World. It is relatively large and differs from other bats in the possession of an independent, clawed second digit; it also depends on sight rather than echo-location in maintaining orientation.
..... Click the link for more information. , found only in the Old World tropics, and the Microchiroptera, or insect-eating bats, with a worldwide distribution. The fruit bats include the largest species of bat, the flying foxes, which may weigh 2 or 3 lbs (.9 to 1.4 kg). Their diet is confined almost entirely to fruit, nectar, and pollen. The insect-eating bats include the smallest bat species. Despite the name, some of these bats live wholly or largely on fruit; a large number eat insects and, in some cases, larger animals. Members of several species catch fish as they skim over water, and the South American vampire batsvampire bat,
name for the blood-drinking bats of the family Desmodontidae, found in the New World tropics. Vampire bats feed exclusively on the blood of living animals and are thus the only true parasites among mammals. There are three species ranging from Argentina to N Mexico.
..... Click the link for more information. feed exclusively on blood.
The most common bats of the temperate Northern Hemisphere are the Old World horseshoe bats (Rhinolophus), characterized by one or two horseshoe-shaped facial appendages, the cosmopolitan little brown bats (Myotis), big brown bats, or serotines (Eptesicus), and pipistrelles (Pipistrellus). The last three, all represented by species in North America, belong to the plain-nosed bat family (Vespertilionidae), characterized by a lack of appendages on the snout.
There are over a dozen species of Myotis in North America; the common little brown bat, M. lucifugus, is distributed over the entire continent from Alaska and Labrador to the S United States. A colonial bat, it is found in many habitats, including houses. It is about 2 1-2 in. (6.3 cm) long without the tail and weighs about 1-4 oz (7 grams). The North American big brown bat, Eptesicus fuscus, of similar distribution, is about three times as heavy, with a wingspread of 12 in. (30 cm). The little and big brown bats are among the species susceptible to white-nose syndrome, which leads to water loss and emaciation during winter hibernation. Identified in 2006 and caused by the fungus Geomyces destructans, it has been devastating to infected bat colonies in North America. Large, solitary North American bats of wide distribution are the hoary bat, Lasiurus cinereus, yellow-brown with silver frosting, and the red bat, L. borealis, which is a striking brick-red color. Both have soft, thick fur and roost in trees.
The freetail bats (family Molossidae) are a cosmopolitan group of communal bats characterized by a long tail extending well beyond the end of the tail membrane. Among them are the guano bats (Tadarida), which live in enormous colonies. Their excrement, called guanoguano
, dried excrement of sea birds and bats found principally on the coastal islands of Peru, Africa, Chile, and the West Indies. It contains about 6% phosphorus, 9% nitrogen, 2% potassium, and moisture. Guano is found mixed with feathers and bones and is used as a fertilizer.
..... Click the link for more information. , accumulates in great quantities in their roosting places and is commercially valuable as fertilizer. Most New World freetail bats are tropical, but several are found in the S United States. One of these, the Mexican freetail bat (Tadarida brasiliensis), is noted for its colonies in the Carlsbad Caverns of New Mexico, numbering an estimated 250,000 to 500,000 individuals. When these bats leave the caves together it takes about 20 min for the entire column to make its exit. This family also includes the mastiff bats (Eumops), largest of the North American bats, with a wingspread of 18 in. (46 cm).
Bats are classified in the phylum ChordataChordata
, phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal skeletal support at some stage of their development. Most chordates are vertebrates (animals with backbones), but the phylum also includes some small marine invertebrate animals.
..... Click the link for more information. , subphylum Vertebrata, class Mammalia, order Chiroptera.
See R. W. Barbour and W. H. Davis, Bats of America (1969); W. A. Wimsatt, ed., Biology of Bats (2 vol., 1970); M. J. Harvey et al., Bats of the United States and Canada (2011).
What does it mean when you dream about a bat? (animal)
Bats symbolize the powers of the unknown or of the unconscious. Negatively, they can represent fear, the threatening power of the unknown, and, traditionally, death. Positively, as creatures who are quite at home in the dark, bats can also indicate the skill and knowledge to face the unknown and/or the unconsciousness.
What does it mean when you dream about a bat? (baseball, Cricket and Other Sports)
Unless one’s dream flows directly out of associations with actual games and bats—either in childhood or in the present—the usual connotations of a stick with which one hits things is that of violence and aggression, though it can sometimes represent authority. Traditional psychiatrists also view anything long and straight—especially something like a bat—as a symbol of the male principle.