> Meanwhile, evolving resistance also comes at a cost. We don’t know that directly, but we can infer it pretty well. If resistance to tetrodotoxin were cheap and easy, everything would evolve it. [..] We don’t know, but we’re pretty sure there must be something. We know that garter snakes outside of the Pacific Northwest are much less resistant to tetrodotoxin. They’ll drop dead from doses that their Oregon cousins simply ignore. So evolving the resistance must have some cost or drawback.
I'm not so sure that's really the case; it's more that for many animals there simply isn't any pressure to evolve (or retain) this trait.
It's not like the natural selection process has a feature list it can tick off. It operates with zero foresight and an incredibly dumb principle: whatever helps procreation.
Cows are not dying due to tetrodotoxin poisoning in significant numbers, as far as I know, so there is no reason for them to evolve resistance to it. The same applies to most animals, including the snakes outside that area.
Your dog can synthesise their own vitamin C and will never develop scurvy. Most animals can do this – humans and some other primates are the exception. An ancestor lost the trait for vitamin C synthesis by chance, and because these primates were living in trees eating lots of fruit with vitamin C, evolution simply didn't notice. There is no disadvantage to being able to synthesise vitamin C, and no advantage in dropping the trait. It didn't affect procreation (at the time). Now we're all stuck with it.
Now, maybe all of this does have a cost for the snakes. But it's far from a given that there is one.
> Turns out there is an answer: the garter snakes sequester the tetrodotoxin, storing it in their livers. This makes them toxic to their own predators.
Interestingly written article. Raises some questions:
>Newts with weaker poison? They get eaten. Snakes with less resistance? Have trouble finding newts they can choke down, and don’t get to steal their poison. So the arms race continues.
How does a snake know that the Newt has weaker/strong poison? Is it leaving some Newts along and eating others, or is it eating any Newt it runs across? Does a strong-poison newt survive snake consumption attempts?
This might be a total tangent, but every time I see “newts”, I think about how Karel Capek actually coined the word robot in his 1920 play R.U.R., and then later gave us War with the Newts...really smart amphibians.
Thanks for sharing.
Oooooh! I saw “I’ll have to teal deer it” and thought it must be some strange idiom. Had to go to Urban Dictionary to find out “teal dear = tl;dr”, and now I feel as dim as a garter snake that’s evolved resistance to large amounts of tetrodotoxin.
They're cute. They're pretty much harmless in my experience.
They swarm all over the PNW, in season. Don't step on them if you can help it. They're not death newts. I'd be a dead commenter if they were death newts.
They swarm all over the trails in spring, and then they're gone for the rest of the season. That's my recollection of it.
I don't live there anymore, maybe they have evolved into these dangerous death newts. One can hope.
> Turns out there is an answer: the garter snakes sequester the tetrodotoxin, storing it in their livers. This makes them toxic to their own predators.
But this doesn't seem as immediate as the newt's defense where it's on the skin and thus causes potential predators to spit them out or even to seize up - meaning that at least some attacked newts survive the encounter. Eating the liver means the snake is dead. And since it's going to be impossible to tell if a particular snake is immune (and is thus potentially toxic) how would this deter predators? (Especially given the limited range of snakes with this immunity and the probability that there are predators of the snakes that don't necessarily have this same limited range - ravens, raptors, etc.)
Christ, I handled these as a kid quite a bit. Add that to the list of reasons I will wonder how I survived past age 10.
I used to keep native snakes and lizards (and inadvertently breed them!), and couldn’t keep newts because I wasn’t sophisticated enough to create the right environments for them. This is one species I kept (and killed, unfortunately). I’ve learned to do it far better since then, but haven’t tried keeping newts again. They’re beautiful little creatures.
Could being a toxic or venemous creature be bad for survivability of a species in the long term if smarter creatures discover you’re lethal and thus become determined to kill your kind on sight?
I once took a group of young people foraging for mushrooms in the Willamette valley on a farm that had loads of these newts. I warned every body not to touch them.
After preparing dinner, one girl got very ill, as did I, while other people who ate the dinner were fine. I was so worried I'd mis-identified some mushrooms.
But turns out she had handled one of these newts and the bacteria had transferred to the mushrooms she picked. I contacted it from washing the mushrooms. I threw up several times that night.
In hindsight, had we not washed the mushrooms as thoroughly as we did, things could have gone much worse.
The impossible predicament of the death newts
(crookedtimber.org)576 points by bdr 5 June 2025 | 183 comments
Comments
I'm not so sure that's really the case; it's more that for many animals there simply isn't any pressure to evolve (or retain) this trait.
It's not like the natural selection process has a feature list it can tick off. It operates with zero foresight and an incredibly dumb principle: whatever helps procreation.
Cows are not dying due to tetrodotoxin poisoning in significant numbers, as far as I know, so there is no reason for them to evolve resistance to it. The same applies to most animals, including the snakes outside that area.
Your dog can synthesise their own vitamin C and will never develop scurvy. Most animals can do this – humans and some other primates are the exception. An ancestor lost the trait for vitamin C synthesis by chance, and because these primates were living in trees eating lots of fruit with vitamin C, evolution simply didn't notice. There is no disadvantage to being able to synthesise vitamin C, and no advantage in dropping the trait. It didn't affect procreation (at the time). Now we're all stuck with it.
Now, maybe all of this does have a cost for the snakes. But it's far from a given that there is one.
Turns out, it's the water-lily.
https://crookedtimber.org/2025/03/14/occasional-paper-the-in...
Second-order effects are so cool
>Newts with weaker poison? They get eaten. Snakes with less resistance? Have trouble finding newts they can choke down, and don’t get to steal their poison. So the arms race continues.
How does a snake know that the Newt has weaker/strong poison? Is it leaving some Newts along and eating others, or is it eating any Newt it runs across? Does a strong-poison newt survive snake consumption attempts?
This might be a total tangent, but every time I see “newts”, I think about how Karel Capek actually coined the word robot in his 1920 play R.U.R., and then later gave us War with the Newts...really smart amphibians. Thanks for sharing.
[0]https://www.discovermagazine.com/planet-earth/a-beautiful-we...
They swarm all over the PNW, in season. Don't step on them if you can help it. They're not death newts. I'd be a dead commenter if they were death newts.
They swarm all over the trails in spring, and then they're gone for the rest of the season. That's my recollection of it.
I don't live there anymore, maybe they have evolved into these dangerous death newts. One can hope.
But this doesn't seem as immediate as the newt's defense where it's on the skin and thus causes potential predators to spit them out or even to seize up - meaning that at least some attacked newts survive the encounter. Eating the liver means the snake is dead. And since it's going to be impossible to tell if a particular snake is immune (and is thus potentially toxic) how would this deter predators? (Especially given the limited range of snakes with this immunity and the probability that there are predators of the snakes that don't necessarily have this same limited range - ravens, raptors, etc.)
I used to keep native snakes and lizards (and inadvertently breed them!), and couldn’t keep newts because I wasn’t sophisticated enough to create the right environments for them. This is one species I kept (and killed, unfortunately). I’ve learned to do it far better since then, but haven’t tried keeping newts again. They’re beautiful little creatures.
Though I remain a tiny bit disappointed that it wasn’t about some arcane royalty arrangement for the band “The Death Newts”.
I can already think of uses of this word jokingly in a people context
After preparing dinner, one girl got very ill, as did I, while other people who ate the dinner were fine. I was so worried I'd mis-identified some mushrooms.
But turns out she had handled one of these newts and the bacteria had transferred to the mushrooms she picked. I contacted it from washing the mushrooms. I threw up several times that night.
In hindsight, had we not washed the mushrooms as thoroughly as we did, things could have gone much worse.