Vampire bat

Vampire bats, species of the subfamily Desmodontinae, are leaf-nosed bats found in the Americas. Their food source is blood, a dietary trait called hematophagy. Three extant bat species feed solely 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, Uruguay and Argentina. Due to differences among the three species, each has been placed within a different genus, each consisting of one extant species. In the older literature, these three genera were placed within a family of their own, Desmodontidae, but taxonomists have now grouped them as a subfamily, the Desmodontinae, in a leaf-nosed bat family, Phyllostomidae. The three known species of vampire bats all seem more similar to one another than to any other species. That suggests that hematophagy (feeding on blood) evolved only once, and the three species share this common ancestor.:163-167 The placement of the three genera of the subfamily, within the new world leaf-nosed family Phyllostomidae Gray, 1825, may be summarised as, Vampire bats are in a diverse family of bats with many food sources, including nectar, pollen, insects, fruit and meat.The three species of vampire bats are the only mammals that have evolved to feed exclusively on blood (hematophagy) as micropredators, a strategy within parasitism.Hematophagy is uncommon due to the number of challenges to overcome for success: a large volume of liquid potentially overwhelming the kidneys and bladder, the risk of iron poisoning, and coping with excess protein.There are multiple hypotheses for how vampire bats evolved. The vampire bat lineage diverged from its family 26 million years ago. The hairy-legged vampire bat likely diverged from the other two species of vampire bats 21.7 million years ago.Because the hairy-legged vampire bat feeds on bird blood and it is the ancestral vampire bat, it is considered likely that the first vampire bats fed on bird blood as well.Recent analyses suggest that vampire bats arose from insectivores, which discount the frugivore, carnivore, and nectarivore hypotheses of origin. Within 4 million years of diverging from other Phyllostomids, vampire bats had evolved all necessary adaptations for blood-feeding, making it one of the fastest examples of natural selection among mammals. Unlike fruit bats, the vampire bats have short, conical muzzles. It also lacks a nose leaf, instead having naked pads with U-shaped grooves at the tip. The common vampire bat, Desmodus rotundus, also has specialized thermoreceptors on its nose, which aid the animal in locating areas where the blood flows close to the skin of its prey. A nucleus has been found in the brain of vampire bats that has a similar position and similar histology to the infrared receptor of infrared-sensing snakes. A vampire bat has front teeth that 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 that processes sound, is well adapted to detecting the regular breathing sounds of sleeping animals that serve as its main food source.