As promised, last Friday’s mystery object turned out to be easy:
The very first reply by Gerry gave the correct species and every subsequent suggestion was for the same animal.
With those huge razor-like incisors and canines what could this be other than a Common Vampire Bat Desmodus rotundus Geoffroy, 1810.
These South and Central American bats are common and adaptable in their habitat preference. They are renowned for their unusual habit of feeding on blood, which has led to some fascinating adaptations in these bats.
They usually feed on livestock (in particular horses, cattle, pigs and chickens) rather than on humans, although every so often they will take a blood meal from a person (potentially infecting them with rabies in the process).
Feeding occurs at night and the Vampire prefers prey (or perhaps that should be hosts) that are sleeping or inactive. They do this with their excellent eyesight, echolocation and heat-sensors in their nose. They will also return to the same animal several times, by using their sense of smell to detect their own urine on an animal they have fed on before.
The bats find an area of the animal that has thin skin and is accessible (like the neck, the ankle or the base of an ear) and they make an incision with their teeth and they lap the blood from the wound (rather than sucking it). As they drink, the blood mixes with their saliva, which contains an anticoagulant that prevents clotting (something that is being studied for use in treatment of strokes).
The bat will consume about half its bodyweight in blood in a single session, but due to highly efficient kidneys much of the weight is quickly lost by extracting the water from the blood plasma and excreting it as urine. The bat will still be too heavy to fly for a while after feeding, but the Vampire has a solution to getting around when full – it bounds on its hind limbs and wings in a very unusual gait.
All in all, Vampire Bats are pretty amazing animals – better than your average fictional vampire any day.