Vampire Bat

The common vampire bat belongs to the family Desmodontidae. The species that belong to the Desmodontidae family are the blood eating bats. The vampire bats are native species of the New World tropics and subtropics region. Desmodus rotundus is the scientific name of the common vampire bat. The common vampire bat, the white-winged vampire bat and the hairy-legged vampire bat are the only sanguivorous bats, which means the blood-eating birds. The scientific name of the white-winged vampire bat is Diaemus, or Desmodus, youngi. The scientific name of the hairy-legged vampire bat is Diphylla ecaudata. The count of common vampire bats are available on a large scale in agricultural areas and feeds on livestock such as cattle, pigs, and chickens. 

The other two vampire species are primarily restricted to intact forests, where they feed on birds, reptiles, and other forest animals.

The common vampire bats are vampire bats who are real blood sucking species. They are tailless and medium-sized species with an average length of about 7 to 9 cm. The vampire bat size completely depends on their blood intake. The weight of the blood sucking bats varies depends on the volume of the blood that they are ingesting. The blood sucking bats are vampire bats really can double their weight in one feeding. The fur on the vampire bats are short and their colours are ranging from brown to reddish-orange. The wings of bats are long and pointed and their first segments of the thumb are exceptionally long, enabling it to hop and creep in a strangely agile, yet frog-like manner along the ground. The common vampire bat is the only bat, that is capable to live in the ground, using its long thumbs to leap a metre or more into the air before flying off.

During the nighttime, the bats will emerge from their roosts in hollow trees or caves. They will generate the sonar waves for travelling in dark space. Further, they detect the location of the prey with heat sensors located in the face. Commonly the bats can land near their resting prey and then jump or crawl toward their prey. They will make a tiny incision in the skin with the razor-sharp incisor vampire bat teeth. The incision usually remains unnoticed by the resting animals, and the vampire bats subsequently lick the blood flowing from the tiny wound created by them. A very strong anticoagulant present in the saliva of vampire bats keeps the blood flow and prevents clotting of blood. Although the wounds created by the vampire bats are not serious, sometimes the seriously infecting microbes may easily enter through the wounds and create huge defects.  Vampire bats are considered pests in a wide range, as they frequently transmit rabies to livestock. Human beings are also infected by vampire bats.

The common vampire bat is the noted creature for its unusual and highly evolved social structure. If a single bat from a group of vampires cannot find enough food during the night, then they will share their meals with others. The vampire bats can give birth to only one bat after their gestation period. The young vampire bats will stay with their mother for several months until they learn to feed on their own. Females and their young bats together form stable groups that roost together. Male bats find their shelter separately, except for the dominant male bats who roost with the females. 

The characteristics of Vampire bats are related to the New World leaf-nosed bats, who belong to the family Phyllostomatidae. And sometimes, they are classified and kept under the subfamily Desmodontinae. The size of new world false vampire bats are much larger than the sanguivorous bats. Although Vampyrum species are aggressive in appearance, their snouts and long canine teeth are used to capture and eat small prey. Various Old World false vampire bats widely are found in Africa, Asia, and Australia.

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Characteristics of Vampire Bat

Physical Characteristics of Vampire Bat

The physical characteristics of vampire bats are different from those of fruit bats. The vampire bats have short conical muzzles. One important feature about vampire bats are, they lack a nose leaf instead of having naked pads with U-shaped grooves at the tip. The common vampire bats will have specialized thermoreceptors on their nose, through which they are locating areas where the blood flows close to the skin of its prey. A nucleus, which is found near the brain of vampire bats that has a similar position and similar histology to the infrared receptor of infrared-sensing snakes. 

The vampire bat teeth present in their front are specialized for cutting and the back teeth are much smaller than in other bats. The inferior colliculus, the part of the bat's brain, processes sound, which are well adapted to detecting the regular breathing sounds of sleeping animals, which are the main vampire bat food.

The vampire bats can easily move on land, can walk, jump, and even run by using a unique, bounding gait, in which the forelimbs instead of the hindlimbs are recruited for force production, as the wings are assisting them to move more powerful than the legs. But fruit bats do not have these special characteristics. The vampire bat’s ability to run seems to have evolved independently within the bat lineage. Usually, the body of Vampire bats have a high level of resistance to a group of bloodborne viruses such as endogenous retroviruses, they insert copies of their genetic material into their host's genome.

Vampire bats will use infrared radiation to locate blood hotspots to detect their prey. The list of other known vertebrates, which are capable of detecting infrared radiation are pythons, boas, and pit vipers, all these species have pit organs. According to a recent study, common vampire bats tune a TRP channel which is heat-sensitive. Through TRPV1 they are lowering their thermal activation threshold to about 30°C. This is achieved through alternative splicing of TRPV1 transcripts to produce a channel with a trimmed carboxy-terminal cytoplasmic domain. 

Life Cycle of Vampire Bat

Usually, vampire bats will choose the darkest place to live such as caves, hollow trees, old walls and buildings. And they are living in colonies. A wide range of vampire bats can encounter from 

Central to South America and live in arid to humid, tropical and subtropical areas. The number of bats in vampire bat colonies are ranging from single digits to hundreds in roosting sites. The basic social structure of bat colonies is made of female groups and their offspring, a few adult males. The adult males in the colonies are also termed, resident males. And the separate groups of males are termed, nonresident males. While absorbing the colonies of hairy-legged vampire bats, the count of hierarchical segregation of nonresident males appears less strict than in common vampire bats. Generally, the nonresident vampire bat males are accepted into the harems when the ambient temperature lowers. 

Generally, the resident male bats mate with the females in their colonies, and it is less common to find the outside males to copulate with the females. The female offspring bats will remain in their mother’s colonies. Male offspring will live in their natal groups until they are attaining the age of two years, but sometimes the male offspring are forcefully ejected by the resident adult males. The Vampire bats form strong bonds with all the members of the colony. Unique characteristics of vampire bats are sharing the food. Because, the vampire bat can survive for only two days without getting blood feed, as they do not have any guarantee about finding food every night they will share their meal. While bats from colonies could not find feed, they would beg with other bats in their group. Donor bats will consume the food as much they require for their survival and share the remaining blood with other bats.  When an individual bat in the colony is lost, bats with a larger number of mutual donors tend to balance their energetic costs at a higher rate than bats that fed less of the colony before the removal.

Other important characteristics about vampire bats are, they can identify and monitor the positions of individuals of the same species simply by antiphonal calling. This is similar to the sound mother bats make to call to their pups, these calls tend to vary from bat to bat, which may help other bats identify individuals both in and outside of their shelter. Vampire bats are also interested in social grooming. This usually occurs between females and their offspring, but it is also notated among adult female bats. Social grooming in vampire bats is mostly related to food sharing. 

Feeding 

The vampire bats will go for a hunt only in completely dark situations. They also emit low-energy sound pulses to find their prey. The main vampire bat foods are the blood of mammals, which includes human beings. Both white-winged vampire bats and the hairy-legged vampire bats' primary feeds are the blood of birds. Once the common vampire bat finds their host, such as a sleeping mammal, they get landed and approach the ground. Then they use thermoception to identify a warm spot on the skin to bite. Further, they create a small incision using their teeth and suck the blood from the wound. Like snakes, vampire bats have highly sensitive thermosensation, This is a specialized system for detecting infrared radiation. The most common vampire bats have a specific option to attack one particular animal, they will attack any warm-blooded animal. Likewise, the white-winged vampire will pay some special preference for birds and goats. 

Usually, the common vampire bat uses its canine and cheek teeth like a barber's blades to shave away the hairs on the skin of the prey, if they found fur on the skin of the host. The vampire bat teeth are razor-sharp, with that they can make a 7 mm wide and 8 mm deep cut. The upper incisors in bats do not have enamel, so they are permanently kept in razor-sharp. Vampire bat teeth are so sharp and they can be cut easily.

The vampire bat's saliva sprayed on the prey may create a bite wound, through which they obtain feed from the wound. Further, their saliva contains several compounds for prolonged bleeding, such as anticoagulants that inhibit blood clotting and compounds that prevent the contraction of blood vessels near the wound.

Digestion

The average weight of vampire bats is about 40 grams and they can consume about 20 grams of blood in 20 minutes. Their anatomy and physiology structures are facilitating their feed behaviour. Further, they can process the blood feed rapidly and digest them as soon as possible. The stomach and intestine of the vampire bats will rapidly absorb the water in the blood meal, which is quickly transported to the kidneys, later to the bladder for excretion. A common blood sucking vampire bats start to expel urine within two minutes of feeding. The amount of blood they consume is about 20 - 30% of their body weight. After the meal, to 

take off from the ground, the bat generates extra lift by crouching and flinging itself into the air.

After completing the meal within the next two hours, the common vampire bat returns to its roost and settles down to spend the rest of the night digesting its meal. Digestion of vampire bats is aided by their microbiome, and their genome protects them against pathogens in the blood. Their stools are roughly the same as that of fruits eating or insects eating bats.