This is my brain on leeches | Hacker News Reader

This is my brain on leeches

todaythings.substack.com

77 pointsaebtebeten26 comments

Leeches can also be used for weather forecasting*, as in the greatest-named invention of all time, the Tempest Prognosticator.

https://en.wikipedia.org/wiki/Tempest_prognosticator

* results may vary.

The original mixture of experts design, perhaps :) Thank you for sharing this!

This is actually a fascinating article, and I am suitably grossed out and fascinated at the same time. Good HN material, in the 'Anything that good hackers would find interesting. That includes more than hacking and startups.' guideline sense.

Sucher's substack is reliably interesting in that way, you should check out the back issues

My PhD research was actually studying the leech nervous system. They're still an important 'model' organism in neurobiology. Probably not as important in the field at large as they were in, say, the 1970s, but still. They're also a good system for neurophysiology education, because they are cheap and easy to obtain, have large-ish neurons that are identifiable from animal to animal, and their nervous system has a relatively simple organization.

The other day someone posted something interesting about leeches. Apparently you can use anti-mosquito spray to make them detach from the skin in minutes.

Saw that comment and I’m pretty sure that it is a bad idea since the article explicitly mentioned that stressing the leeches causes them to “vomit blood back into your bloodstream” and introduces a risk of bacterial infections. The advice was to use a credit card to quickly break the suction seal and force the leech to detach.

We've used pocket hand sanitiser to make Leeches to detach.

Your local hospital quite likely currently has a tank of leeches. They are still used in surgery. Especially after reattachment surgeries. They secrete anticoagulants which prevent blood clotting. They are also used in microsurgery to increase blood flow to a certain area.

Is there some reason why we can’t either extract those anticoagulants from the leeches or otherwise synthesize them?

From Wikipedia (https://en.wikipedia.org/wiki/Hirudo_medicinalis)

> Because of the minuscule amounts of hirudin present in leeches, it is impractical to harvest the substance for widespread medical use. Hirudin (and related substances) are synthesized using recombinant techniques. Devices called "mechanical leeches" that dispense heparin and perform the same function as medicinal leeches have been developed, but they are not yet commercially available.

Leeches are very much in use today in the US, in operating rooms especially!

Also, sterilized maggots are used for maggot debridement therapy to clean necrotic tissue from wounds. They don't touch living fresh.

Careful! That depends on the species.

https://www.usda.gov/about-usda/news/press-releases/2025/08/...

https://en.wikipedia.org/wiki/Myiasis#/media/File:Wounds_myi...

(you will never be able to unsee this)

TIL that we have a legit leech distributor down the road.

https://leechesusa.com

It's a bigger business than most people realize. Most operating rooms probably maintain a tank of leeches. They are used in reattachment and plastic surgery as well as microsurgery

Certainly didn't expect to read about leeches today (or Napoleon's piles) but hey that's what's great about HN

I would be down to try leeching but I have an irrational fear theyre gunna lay eggs in my bloodstream.

Ssh... don't fight the symbiosis... accept your fate

EXACTLY what a cordiceps host would say!

You'll be fine. I went swamp swimming plenty as a kid and my grandmother would salt the leeches off me.

Nice!

That reminds me of https://www.cbc.ca/news/science/bloodsuckers-1.5361074 where I learned:

"... resist the temptation to pour salt on [a bloodsucking leech], as folk wisdom recommends, because that could cause the leech to vomit into the wound, posing unnecessary health risks, suggest biologists behind a new exhibit on bloodsucking animals."

Swimming in Minnesota lakes: always check for leeches. It seems like they hang out close to shore, so swimming near the dock or weeds increases the chance of being an involuntary blood donor.

New Guinea: they have land leeches that hang out at the end of branches, like ticks. Hikers use anti-leech sleeves and gaiters.

I say: nuke from orbit, it's the only way to be sure. ;-)

Okay, yea, that was a fun read. Thanks for the article/post/what the heck is the right term anyway! I learned lots of things I did not expect to learn today.

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