'Pit organs' around the nose of vampire bat detects infrared radiation using ion channels.

“Histological studies of the bats’
facial structures indicate that thermal stimuli are most probably
perceived in the three pits surrounding the central nose leaf: the thin,
hairless and glandless skin is underlaid with dense connective tissue.
Thermography reveals that the surface temperature of the nasal region is
up to 9°C lower than that of the neighboring parts of the face (Fig.
2).” (Kürten and Schmidt 1982:223)

“Vampire bats (Desmodus rotundus) are obligate blood feeders that have evolved specialized systems to suit their sanguinary lifestyle.
Chief among such adaptations is the ability to detect infrared
radiation as a means of locating hotspots on warm-blooded prey. Among
vertebrates, only vampire bats, boas, pythons and pit vipers are capable
of detecting infrared radiation.
In each case, infrared signals are detected by trigeminal nerve fibres
that innervate specialized pit organs on the animal’s face.
Thus, vampire bats and snakes have taken thermosensation to the extreme
by developing specialized systems for detecting infrared radiation. As
such, these creatures provide a window into the molecular and genetic
mechanisms underlying evolutionary tuning of thermoreceptors in a
species-specific or cell-type-specific manner(…)Here we show that vampire bats tune a channel* that is already
heat-sensitive, TRPV1, by lowering its thermal activation threshold to
about 30°C. This is
achieved through alternative splicing of TRPV1 transcripts to produce a
channel with a truncated carboxy-terminal cytoplasmic domain. These
splicing events occur exclusively in trigeminal ganglia, and not in
dorsal root ganglia, thereby maintaining a role for TRPV1 as a detector
of noxious heat in somatic afferents.” (Gracheva et al. 2011:88)

*Ion channels are pore-forming proteins that regulate the flow of ions across the membrane in all cells.

The channel acts like a little thermostat. “Altering its structure by leaving out part of the gene tunes the
ability of the channel to detect heat. By expressing different forms in
different tissues, the bats have split the function of the sensor,
maintaining its original function but also gaining the ability to
detect body heat for more efficient hunting.” (Wigmore 2011)

Last Updated August 18, 2016