AKA: how Much Blood have the right to A Leech Drink

We’re all familiar with the old medical practice of leeching. Once we think about leeching, we think around days back when the score of medicine was simply to make a change. Ago when barbers carry out surgeries and doctors believed everyone was made up of bile and also phlegm.

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While the usage of leeches in medicine dates back to ancient Egypt, it’s tho in presence today. Because that the many part, they’re provided in surgeries since of their capability to secrete anticoagulants. Leech treatment is make a little bit of a comeback in Hungary and also Sweden wherein it is supplied in a grasp of treatments.

Woman using medicinal leeches from HistoriaMedica,1638

All in all, what every these species of treatments throughout time have in common, is they depend on the leeches appetite for blood.

Are Leeches actually Voracious Blood Suckers?

Just around anything that drink blood gets a bad name. And of the 700+ varieties of leeches out there, the vast majority drink blood. Regardless of this, they’re solid vicious animals. Some varieties are also full-on vegetables – eat decaying plants.

Others don’t loss into one of two people category. The red worm feeds ~ above its prey by swallowing the whole:

Leeches have the right to be timid v humans. Make the efforts to pressure a leech come bite you have the right to be difficult. They prefer a stealth attack, for this reason if you choose one up and put the on friend it’s more likely to try and shuffle away.

As well, their key target is typically frogs and other amphibians. That course, they won’t shy away from mammals offered the opportunity.

What to do if you’re bitten through a leech?

If a leech bites you, odds are you won’t even know. Together we mentioned, they’re all around stealth. They’re aquatic ninjas, sneaking up on unsuspecting prey. Biting right into their prey, castle secrete anesthetics and also anticoagulants right into the human body while at the same time sucking out blood.

The anesthetic keeps you from feeling the pain, civilization often don’t notice they’re bitten. And the anticoagulants keep the blood flowing. Together well, without the anticoagulants in the leeches system, the drained blood would eventually clog increase in them, puffing them up into a St. Macy’s day Parade balloon version of a leech.


The most likely reason you’d an alert a leech is the its feeding session is pretty long. They’ll often feed for 20 come 40+ minutes.

If friend do notice a leech, you can just traction it off. They nothing burrow right into your body or leave behind teeth, for this reason removal isn’t really painful or risky. The anticoagulant keeps the wound from closing, however it’s quite small.

Is A Leech Bite Dangerous?

A solitary leech no a threat. The only concern really would be the rare instance where who is allergy to the bite. Even then, reactions space not commonly severe. More likely, you’ll simply want to make certain the wound doesn’t get infected. Particularly if you’re the end in the wilderness.

Even ~ the lengthy feeding session a leech just takes around 5-15ml the blood, relying on their size. For this reason you’re going to it is in okay.

In fact, you can want to leaving it ~ above while it feeds. Take images with her camera or phone. Observe and note any kind of patterns, colouration and movement. You can get lucky and discover a brand-new species.

How numerous Leeches would It require to Kill A Human?

You’re established to perform this, aren’t you? it is okay, the that same morbid curiosity that got us to compose this in the first place. Depending upon the dimension of the leech and the person, it would take about 300 come 1100 leeches come bleed an adult human dry, or 120 to 440 leaches to kill.

The number on that job-related out pretty simply. The average human being adult has around 4.5 to 5.5 litres the blood, and leeches suck around 5-15 ml in one session. After ~ a feeding, leeches have the right to subsist ~ above the blood for number of months. Therefore we determined to only count one feeding every leech because your body will reproduce every the blood long before they must feed again.

Of course, a person would die long before bleeding the end completely. Generally, as soon as you lose around 40% of your blood your body loses the capacity to manage blood pressure and also you have actually a high hazard of death.

We offered Hirudo Medicinalis, a common medicinal leech because that these numbers. That course, if you desire to take it a look at a species like the 18” gigantic Amazon Leech, we’re looking at a creature an ext than twice the size, therefore it would certainly take far fewer to acquire the task done.

Giant Amazon Leech (Haementeria Ghilianii) with his pet human.

But the wouldn’t happen, right?


Lower invertebrates, choose leeches, perform to often tend to type swarms when they’re in groups. Swarms have the right to be anywhere from 10s to 1000s. And also leeches have been it was observed in large group formations.

In theory, an opportunistic leech swarm might attack and also kill a completely grown adult. Although that would rely on the human not fighting lock off. Even if you a at sight deep sleeper, just about anyone is going to notification thousands the bites all at once, even with the anesthetic secretions.

All in all, that pretty unlikely.

Although it’s no to to speak leeches room altogether harmless. There have been deaths from civilization in north Kenya drink water containing the Myxobdella Africana leech. The victims experienced anemia, causing death. In cases treated through blood transfusions, the patients have survived.

Not come forget, as freshly as 2008, a 65 year old man in Turkey to be rushed come ER v 130 leech bites. Fortunately, he made it through after receiving 8 units of frozen plasma. If the weren’t because that the quick intervention the an outcome could have actually been worse.

Still, most of the time, leeches are low to no risk. Their negative reputation originates from their blood-sucking nature and also their virtually alien genetics.

But, as long as we’re talking about hypotheticals, why stop at humans…

How numerous Leeches would certainly It require to Kill A Blue Whale?

Image by chase Dekker

A blue whale is big. And also not the means other pets are. Consider an elephant, it is a big animal. An average African Elephant weighs about 12,000 lbs – that a lot. However in a blue whale, their blood alone weighs 14,000 lbs.

An whole blue whale is more like 140,000 kg (about double the weight of a an are shuttle). It’s much easier to compare them to buildings than to various other animals. In the animal kingdom, lock the biggest, heaviest things that’s ever existed.

What we’re saying, is this is going to take a many leeches.

For the services of ease we’re suspect we can keep the same proportion as because that sucking blood the end of human beings (5-15 ml per session). Alright, let’s gain a little nerdy here:

Since us don’t have actually blue whale blood handy, we’re suspect a blood weight of 1.04 g/cc (1000 g = 1 kg, 1000 cc = 1 liter) 14,000 kg of blood equates to roughly 13,461.539 litersThat’s 13,461,539 mlThe typical leech sucks 5-15 ml13,461, 539 ÷ 5 = 2,692,307.8 13,461, 539 ÷ 15 = 897,435.9

So relying on the dimension of the leeches it would certainly take about 900 thousand to 2.7 million leeches come bleed a blue whale dry. Or about 360 thousand to 1.1 million to kill (assuming the 40% blood loss holds true because that whales).

Leech Bonus Facts:

Alien Genetics!

Okay, they aren’t aliens, but they certain are choose something out of a sci-fi movie. We’re talk creatures with eco-friendly blood, 32 brains, 10 stomachs, 18 testicles, and also 2 to adjust of genitalia. It’s no what you’d speak to normal.

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32 Freakin’ Brains?

Having two sets the genitalia is perhaps the the very least weird thing about leech biology. Leech bodies division evenly into 32 segments. If they’re much from the only animal with segmented organs, castle still unexplained as every of your segments has actually its own brain.

That doesn’t typical you can reduced a leech right into 32 pieces and have it live on, however it’s certainly strange.