Today is International Bat Appreciation Day. It sounds intriguing, doesn’t it? Bat Appreciation Day.
You know that bats don’t have the best reputation among people. They are often regarded as spooky and mysterious creatures and associated with Halloween, darkness, vampires, and caves. So, I was wondering why one can appreciate them?
Well, it turns out that there are over 1400 different species of bats on Earth, and many of them play an important role in getting rid of insect pests, dispersing seeds, and pollinating flowers. So, it seems that many of these fascinating animals, which, by the way, are the only mammals capable of sustained flight, are in fact very helpful. Many, but not all of them.
There is, in fact, a type of bat that is considered an agricultural pest. They are very similar to most other bats – they come out at night, can fly, and use echolocation for navigation and finding prey. There’s one important difference, however – they feed exclusively on the blood of other animals (sometimes even humans). And I’m sure you can guess from the first try what their name is – the Vampire Bats.
One interesting peculiarity of vampire bats is that they can detect hot spots on their prey where blood flows close to the skin. So, these bats don’t just bite where they have landed on their victims. They will first look for the most suitable place to bite (where they’ll have the easiest access to blood), and then create a small incision with their blade-sharp teeth and lap up blood from the wound with the tongue. Almost like a cat lapping up milk from a dish.
So, how do vampire bats find these hot spots?
In 2011, David Julius’s group found that the Vampire bats developed specialized systems for detecting infrared radiation, and the key to these systems is the TRPV1 ion channel, which is well-known as a pain, capsaicin, and noxious heat receptor (read here).
It turned out that these bats have two kinds of TRPV1 receptors: “normal” and short. As in other species, the “normal” TRPV1 of the vampire bats is expressed in sensory neurons and functions as a detector of noxious heat. The short TRPV1, however, was found only in trigeminal ganglia, innervating the pit organs surrounding the vampire bat’s nose. Surprisingly, this short TRPV1 turned out to be activated at a substantially lower temperature threshold compared to normal TRPV1 (30°C vs 40°C), allowing the bats to detect heat from veins and arteries of their victims.
Who knew that ion channels were the key to a vampire’s hunting success.
Picture by Oasalehm, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons