Dracula’s Children
2013 06 26

by Carl Zimmer | Phenomena



Millions of years ago, some bats gave up their old habits of hunting for insects and tried something new: drinking blood. These creatures evolved into today’s vampire bats, and it’s mind-boggling to explore all the ways that they evolved to make the most of their sanguine meal.

A lot of the adaptations are easy enough to see with the naked eye. Vampire bats have Dracula-style teeth, for example, which they use to puncture the tough hide of cows. When they open up a crater-shaped wound, they dip in their long tongue, which contains two straw-shaped ducts that take up the blood.

Finding these prey has led to another remarkable adaptation that you can see–at least if you’re a scientist who studies how vampire bats move. Like other bats, they can fly, but on top of that, they can also walk and, yes, even gallop. Here is a video of a running vampire bat made by Dan Riskin (see this Loom post for details). Of the 1200 or so species of bats, vampire bats are among the very few that can move quickly on the ground.



But vampire bats have many other adaptations for drinking blood that are invisible. They use their combined senses–long-range vision, a sharp sense of smell, acute hearing, and echolocation–to find their victims. In their noses, they even have heat-sensitive pits that detect the heat of warm-blooded animals. Once they land on an animal, they apply those pits to the skin to locate capillaries full of hot blood close to the surface.

When vampire bats dip their tongue into a wound, they don’t just draw out blood. They also put their saliva into their victim. And in this liquid are still more invisible adaptations for a blood-feeding life. Vampire bats, you see, are venomous.

This may sound odd. That’s because we usually think of venom as a chemical an animal sticks in your body to cause you pain or death. But biologists define venom more broadly than that: it’s a secretion produced in a specialized gland in an animal, which is delivered to another animal by inflicting a wound, where it can disrupt its victim’s physiology.

Snake venom, the sort we’re all most familiar with, can disrupt physiology to the point of death. And it does so in several ways–jamming neurons, for example, or causing tissue to rot. But other animals that don’t set out to kill their victims also produce venom. Vampire bats, for example, don’t want eat a whole cow. They just want to take a sip.

Unfortunately, drinking blood has some drawbacks. Vertebrates come equipped with lots of molecules and cells that plug up wounds. As soon as they sense even a tiny tear in a blood vessel, they start making clots to staunch the flow.

Vampire bats use venom to keep the blood flowing. In a new paper with a title worth quoting in full–“Dracula’s Children: Molecular Evolution of Vampire Bat Venom”–an international team of scientists explore the molecules that vampire bats use to subvert blood’s defenses.

What’s most striking about vampire bat venom is how it goes after its victim from so many directions. Blood clots develop through a series of reactions that involve a chain of enzymes. Vampire bats produce different proteins to go after different enzymes in that chain. Platelets, which are cell fragments, also clump around wounds to help heal wounds. Vampire bats make separate compounds that attacks platelets.

[...]

Read the full article at: nationalgeographic.com




Related Articles
Real-Life ’Vampire’ Addicted to Blood, Doctors Claim
"The Vampire Tarot" by Robert M. Place
Serbian village puts out vampire warning, advises to stock up on garlic
Bram Stoker books: How ’Dracula’ created the modern vampire
The Great New England Vampire Panic
15th annual European "Bat Night": For the Love of Bats


Latest News from our Front Page

Election Posters in New Sweden
2014 08 27
Swedish prime minister Fredrik Reinfeldt has promised continued mass immigration at the expense of welfare reform and tax cuts. Reinfeldt’s Moderates party consequently does everything in their power to recruit immigrants’ votes. Placards for the forthcoming elections, widely distributed in immigrant-dominated enclaves in Sweden, has Arabic text, the language that now increasingly is dominating major parts of "New Sweden." In the ...
Gender Madness
2014 08 27
Gender Madness - RT RT: "Tanya, a mathematician from Sweden, is writing a blog about gender madness. She wants to find its origins. She discusses the topic with different people, meets some gender specialists and even considers conducting some experiments." Yes, this is a very erratic and "different" short film, but Kajsa Bergkvist, the girl making the film has a ...
Could Greece’s mystery tomb lie intact? Well-preserved headless sphinxes
2014 08 27
Well-preserved headless sphinxes hint that grave dating back to Alexander the Great Archaeologists are hopeful that an ancient mound in northern Greece could hold the untouched remains of an important senior official from the time of Alexander the Great. Excavations at the ‘incredibly important’ tomb have revealed a pair of sphinxes guarding the grave’s entrance. The two sculptures were found under an arch ...
Horrifying accidents at infectious disease labs hidden from the public, ‘cloaked in secrecy’
2014 08 26
Literally hundreds of incidents involving viruses, bacteria and toxins that pose major bioterror risks to both people and agriculture have been reported to federal regulators from 2008 through 2012, according to government reports obtained and reviewed by USA Today. More than half of the over 1,100 incidents were serious enough that laboratory workers had to have medical evaluations and/or treatment, the ...
Those Who Know They’re Dreaming Are Savvier When Awake
2014 08 26
It’s probably fair to assume that at this moment, you are, in fact, awake. You’re reading; you’re scrolling; sometime in the not-too-distant past, you somehow made your way to The Atlantic’s website. All waking activities. But let’s say, hypothetically, that as you’re reading this, the floor and everything else beneath you dissolve, leaving your body floating where your chair had been ...
More News »