Infrared sensing in vampire bats

Vampire bats are the only known mammals whose entire nutrition relies on blood from mammals or birds. In the family Phyllostomidae and the subfamily Desmodontinae, there are three known species of vampire bats: Desmodus rotundus (common vampire bat), Diphylla ecaudata (hairy-legged vampire bat), and Diaemus youngi (white-winged vampire bat). Most of the referenced research on infrared sensing in vampire bats has been done on the common vampire bat because this is the most commonly found species. These bats have developed a specialized system using infrared-sensitive receptors on their nose-leaf to prey on homeothermic (warm-blooded) vertebrates.Trigeminal nerve fibers that innervate these IR-sensitive receptors may be involved in detection of infrared thermal radiation emitted by their prey. This may aid bats in locating blood-rich areas on their prey. In addition, neuroanatomical and molecular research has suggested possible similarities of IR-sensing mechanisms between vampire bats and IR-sensitive snakes. Infrared sensing in vampire bats has not yet been hypothesized to be image forming, as it was for IR-sensitive snakes. While the literature on IR-sensing in vampire bats is thin, progress continues to be made in this field to identify how vampire bats can sense and use infrared thermal radiation.

Vampire bats were not studied in their natural habitats until about 1935. During predation, bats first spend a few minutes in the air circling the target prey, eventually landing on the back or neck crest of the animal, and sometimes the ground. They then proceed to search for a suitable spot to bite, which can take seconds to minutes, and usually will feed on the neck or flank. The same spot may be fed on multiple times by different bats. Kürten and Schmidt (1982) were the first to suggest that infrared perception in vampire bats is possibly used in detecting regions of maximal blood flow on targeted prey. Although warm receptors are also found in the facial regions of species such as mice, humans, and dogs, the extreme low-temperature sensitivity of these receptors on vampire bats suggest specialization for sensing infrared. (see section on Physiology).

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