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Vampire bat

2007 Schools Wikipedia Selection. Related subjects: Mammals

               iVampire bats
   Common Vampire Bat, Desmodus rotundus
   Common Vampire Bat, Desmodus rotundus
         Scientific classification

   Kingdom:   Animalia
   Phylum:    Chordata
   Class:     Mammalia
   Order:     Chiroptera
   Family:    Phyllostomidae
   Subfamily: Desmodontinae'

                                   Genera

   Desmodus
   Diphylla
   Diaemus

   Vampire bats are bats that feed on blood ( hematophagy). There are only
   three bat species that feed on blood: The Common Vampire Bat (Desmodus
   rotundus), the Hairy-legged Vampire Bat (Diphylla ecaudata), and the
   White-winged Vampire Bat (Diaemus youngi). All three species are native
   to the Americas, ranging from Mexico to Brazil, Chile, and Argentina.
   Contrary to popular belief, these bats rarely bite people because they
   apparently dislike human blood.

   The three species are quite different from each other, and are
   therefore placed within different genera (no other species are
   currently classified in any of the three genera concerned). But they
   are related. In older literature, the three genera are placed within a
   family, Desmodontidae, but this is now regarded as unhelpful, as it
   hides the similarities the vampire bats have with other members of the
   American leaf-nosed bat family, Phyllostomidae. They are therefore now
   grouped as a subfamily, the Desmodontinae within the Phyllostomidae.
   The fact that the three known species of vampire bat all seem more
   similar to one another than any of them is to any other species
   suggests that sanguivory (feeding on blood) only evolved once, and that
   all three species share a common ancestor.

   Unlike fruit-eating bats, the vampire bats have a short, conical muzzle
   without a nose leaf. Instead they have naked pads with U-shaped grooves
   at the tip. The common vampire bat also has specialised infrared
   sensors on its nose (see ). A nucleus has been found in the brain of
   vampire bats that has a similar position and has similar histology to
   the infrared nucleus of infrared sensitive snakes.

   They have small ears and a short tail membrane. Their front teeth are
   specialised for cutting and their back teeth are much smaller than in
   other bats. Their digestive systems are also specialised for their
   liquid diet. The saliva of vampire bats contains a substance, draculin,
   which prevents the victim's blood from clotting. They, therefore, lap
   blood rather than suck it as most people imagine.

   They come out to feed only when it is fully dark. Like fruit-eating
   bats, and unlike insectivorous and fish-eating bats, they only emit
   low-energy sound pulses. The Common Vampire Bat feeds mostly on the
   blood of mammals, whereas the Hairy-legged Vampire Bat, and the
   White-winged Vampire Bat feed on the blood of birds. Once the common
   vampire bat locates a host, usually a sleeping mammal, they land and
   approach it on the ground. A recent study found that common vampire
   bats can, in addition to walking, run at speeds of up to 1.2 meters per
   second. They possibly locate a suitable place to bite using their
   infrared sensors.

   The feeding pattern of the vampire bat adds a layer of complexity to
   its anatomy. Because they often do not find host organisms for many
   hours and may have to fly a long distance to do so, vampire bats
   usually feed in enormous quantities. This influx of proteins may make
   the bat too heavy to fly. Accordingly, the bat's urinary system
   accommodates this by releasing dilute urine consisting of a lot of
   water and fewer solutes. However, when the bat is resting, a new
   problem is faced. The large amounts of protein create excess urea and
   must be disposed of. The urinary system of the vampire bat then uses
   various hormones to make concentrated urine -- consisting of more urea
   and less water.

   Vampire bats tend to live in almost completely dark places, such as
   caves, old wells, hollow trees, and buildings. Colonies can range from
   a single individual to thousands. They often roost with other species
   of bat. They will almost always have only one offspring per breeding
   season. Each colony will typically contain only one reproducing male,
   with around twenty females and their offspring. They need blood at
   least once every few days to survive. If they can't get blood, they'll
   approach another vampire bat whilst roosting, asking for a blood
   'transfusion'. The blood is exchanged mouth-to-mouth in a motion that
   looks very much like kissing. Vampire bats can live up to 9 years in
   the wild and up to 19 in captivity.

   Vampire bats are common carriers of the deadly rabies virus which,
   aside from its danger to humans, is responsible for the deaths of many
   thousands of farm animals each year in tropical and sub-tropical
   America. However they do provide some benefits. A study which appeared
   in the January 10, 2003 issue of Stroke: Journal of the American Heart
   Association, tested a genetically engineered drug called desmoteplase,
   which uses the anticoagulant properties of the saliva of Desmodus
   rotundus, and was shown to increase blood flow in stroke patients.
   Retrieved from " http://en.wikipedia.org/wiki/Vampire_bat"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
