Ah, leeches, everyone’s favorite creepy crawly. They’re admittedly not the most adorable animal, but what they lack in any kind of cute, they make up for with the ability to suck your blood without you knowing about it. It’s true that most leeches are sanguivorous, (though some hippy types prefer mushy leaves) but that’s not necessarily a bad thing… unless you’re super attached to your blood and don’t like sharing.
Leeches are actually a type of worm, closely related to the humble and not at all bloodthirsty earthworm who pretends that they’re not related whenever they’re seen together in public. There are over 650 different types of leeches, and they live in forests, lakes and the sea. Some can even grow up to 16 inches long, which means that you’ll probably see them coming, but it also means that you might freeze, whimper and look to the leech like you’d quite like a hug.
While you’re standing there, thinking about how you should have stayed in bed and trying to figure out if it’s possible to survive on nothing but Lucky Charms and Mountain Dew, the leech is in attack mode. Leeches are actually really dumb, and even though they have 32 brains, they’re blessed with a rubbish 63 times fewer neurons than a honey bee. So if a leech does manage to get a grip on you, it’s probably more due to Cosmic Ordering than Sherlock-style prowess. Their bodies do sense disturbances in the environment, though, like changes in temperature, light and vibration, causing them to get a tad hyper and hurry towards their unwilling victim. Oh yeah, and they have eyes, too – lots of eyes. The medical leech has five pairs. More on that guy later…
Leeches suck. No really, they actually suck. Leeches have suckers on both ends of their body, letting them attach themselves to you with one sucker, flip over, attach, flip over, attach and wriggle up and up until they find your tasty spot. If you’re really not into the idea of being lunch, this is the best time to flick them away, with your skin and dignity (for the most part) intact. The leech grabs hold of you with his teeth – which are tough enough to saw through hippo skin, by the way – making a cool Y-shaped incision. Don’t worry, though, it won’t hurt. Leeches release an anaesthetic, not just because they care about your comfort, but also because they want to stay happily guzzling your blood for as long as they can. Leeches also release an anticoagulant called Hirudin, which prevents blood clotting, allowing the blood to flow nicely.
If you pull the leech off now, you will have a serious bleeding problem. Bad idea. It’s best to wait it out, but that might take a while, since your little leech friend is HONGRY. Leeches can take in blood that’s five times their body weight. But they’re not greedy. A leech can survive up to a year without eating again after a big meal. They’re tough in other ways, too. Leeches can survive the loss of 90% of their body weight and can live up to 10 years.
While you’re waiting for the leech to finish sucking down your blood like it’s a super-sized soda, it might be a good time to think about how much leeches have helped people. This is where the medical leech comes in, wearing his stethoscope and looking important. Leeches have been used in medicine for thousands of years, for bloodletting mainly, but also for their anticoagulants and anesthetics. Leeches have been used in recent medicine for helping to reattach body parts, like errant fingers and toes, since there needs to be a constant blood flow to keep the appendages alive. Leeches were so in demand that in the past, leech collectors used to stand in lakes, just waiting to make a few dozen leech friends to take home. Unfortunately, leeches were so popular that they’re now facing extinction, and they’ve been given the same protected status as the white rhino.
The coolest thing that leeches have ever done is the tempest prognosticator, otherwise known as the leech barometer. A dude called George Merryweather realised that although leeches are dumb, they can feel changes in atmosphere. So he created a contraption that comprises of bottles, tubes and a bell. When a thunderstorm is coming, the leeches freak out, crawl upwards and set off a hammer which rings a bell. When speaking about his invention, Merryweather said, “My breasts can always tell when it’s going to rain. Well… they can tell when it’s raining.” I think he meant leeches.