What is the bio-mechanical plausibility of humanoid vampyres exracting blood by biting into a person's neck?

Question

I've tried to find relevant sources to make this question more informed, but haven't had any luck. It just seems implausible to me that a humanoid with long and pointy canines could bite a victim in the neck, hit the jugular vein in two places with those same teeth, drink the blood either through hollow teeth or around the teeth, and withdraw the teeth from the wound without having the victim lose enough blood to die before the vampire wants him to.

Authors have worked around this supposed physical awkwardness. One story depicted a vampire whose feeding organ was a needle-like structure under the tongue. The famous "Strain" series created a special blood-sucking organ that projected more than a yard from the mouth when it struck the victims like a snake. I think there was another author who gave vampires the power to dislocate their jaws so that their mouths could fit comfortably around the neck. I once read a story about a vampire who fed from his victims' wrists.

I have thought about giving my vampire retractile claws so that it could use its hands to puncture or slash wherever it likes, and drink from almost any part of the body.

Is the usual way that vampires feed in the movies and TV plausible?

Well, no it's not. And I'm surprised you didn't find any sources - I remember seeing many about how implausible the "normal" fangs-to-the-neck depiction is. And I've not even gone out of my way to find them. — VLAZ, Jan 08 '20 at 06:07
Related: https://worldbuilding.stackexchange.com/q/34382/21222 — The Square-Cube Law, Jan 08 '20 at 06:08
Also related: https://worldbuilding.stackexchange.com/q/138669/21222 — The Square-Cube Law, Jan 08 '20 at 06:11
Why not give your vampires a "clotting factor organ" which they use to inject material to seal the hole after drinking? — Carl Witthoft, Jan 08 '20 at 16:34
BTW, the main reason for vampires to chomp on the neck is that (in movies) the victims are usually hot young women and an exposed neck is erotic. — Carl Witthoft, Jan 08 '20 at 16:34

score 3 · Answer 1 · answered Jan 08 '20 at 06:24

As long as the vampires maintain a pressure seal, there will only be a momentary drop in the victim’s blood pressure as the blood fills their mouth. After that as long as they maintain the proper pressure, the victim won’t loose any blood and won’t have their brains starved of oxygen carrying blood.

While their fangs have delivered a mortal blow, they can swallow a small amount of blood at a time rather than gulp it down. They’d be able to keep their victim alive for a very long time under these conditions.

With all that blood swirling and sloshing, it could start clotting. If the clots moved into victim’s circulatory system, then they might stroke out.

score 3 · Accepted Answer · answered Jan 08 '20 at 16:22

The jugular vein is a favorite site for placing central venous catheters. The reasons for that are the same reasons your vampires would favor them.

There are two: external and internal. Both are large. Internal is larger.
They are fairly superficial. In some people you can see them. So: fairly accessible.
There are collaterals on the other side. Some people get by with just one side functioning, draining both halves of the head. If you get a clot on one side it will be ok.
The veins in the neck are low pressure - pretty much just the force of gravity. Up at the top of the head venous blood is under even less than atmospheric pressure. A wound to the jugular vein will probably not cause a person to bleed out.

Consider now alternatives. The carotid artery in the neck is muscular and small and would be hard to pin down with a fang. A big wound to the carotid might be life threatening. Thigh veins and arteries are deeper, often covered by clothes and tissues, and under more pressure. The radial artery in the wrist could be an option - superficial, high pressure. You definitely can bleed to death from a wound in the radial artery if you are a Roman senator in his bath - but not necessarily. If the artery is partly intact it could clamp down and stop bleeding. The hand normally has collateral supply from the ulnar artery so losing the radial artery should not stop arterial blood flow to the hand.

score 2 · Answer 3 · answered Jan 08 '20 at 06:57

Is there any real need for a vampire to bite the victim in the neck? If the worry is that exposure to oxygen causes blood-clotting (and that's somehow problematic for vamps), my answer might be of no use, but have you considered having those vampires resort to exsanguination/bloodletting instead?

Humans in the past have resorted to bloodletting (basically medically-approved life-threatening blood loss) as a way to treat ailments(I won't go into the details of why our ancestors thought that was a good idea here, but look it up if you're interested). It depends on how obviously you want your vampires to differ from humans in terms of physiology, but if they aren't too obviously different, they might have better luck masqueraiding as a doctor and drinking the blood they extract from their "patients" instead of abducting people and puncturing their arteries.

What is the bio-mechanical plausibility of humanoid vampyres exracting blood by biting into a person's neck?

3 Answers3