Newly discovered spider builds spring loaded snare to catch ants

https://phys.org/news/2026-06-newly-australian-ballista-spider-snare.html

by chimpanzee • 24 days ago

270 64 24 days ago

I wonder why biological organisms are capable of such absurdly high accelerations. Article reminded me of cnidocytes which apparently produce anywhere between 40,000 and 5,410,000 g. Is it because of the small masses involved?

ajuc• 22 days ago

Strength of fibers scales with crossection area, mass scales with volume.

salynchnew• 21 days ago

There are probably some other interesting adaptations involved, like the fact that the surface of a mantis shrimp's (shell? carapace?) selectively filters out sound waves (and thus, shockwaves caused by its own "punch").

pvaldes4• 22 days ago

If they would prove that the trap also breaks the ant neck, saving venom, or stunning the prey for easy kill, that would be incredible. Somebody needs to include this thing in the script of a science fiction film.

euroderf• 21 days ago

Somebody needs to include this thing in the script of a science fiction film.

"The Fly" is ready for a quick rewrite.

Foskya• 22 days ago

It is truly fascinating, I wonder how it evolved like that. Before becoming a spring as it is today how was it hunting in the past? What constraints made it need such a mechanism instead of a typical web?

pvaldes4• 22 days ago

Injured Himenoptera are known to send pheromones that trigger a vicious defensive response from other members of the colony. On a typical web the companion ants would do what the ants do. Go to war and flood the place surrounding the danger until eventually killing it. The spider does not have neither the stamina, nor the venom amount to deal with that. This web is designed to extract just one ant, while cutting the path that the ant rescuers could follow.

This is the first spider web known designed to catch only one species of prey. That alone would make the finding extraordinary. The trap can lure only green ants and serve the food exactly were the spider wants it; granting access to a common source of food that is everywhere, but also that is very dangerous to hunt (as much big as the spider, with powerful jaws, and much stronger).

The video shows one most interesting thing: Notice that the spider is carefully moving out of the way, just a second before the ant is launched. The spider knows in advance that its current location is about to be hit by a bungee jumping ant, and acts accordingly just in time to avoid the "bullet". We can easily imagine the spider thinking 5,4,3... This means that spider brains can predict the future outcome of a complex movement of objects in the physical system of its trap, and also calculate how much time the fibers will resist the jaw of the ant.

sethammons2• 22 days ago

The smart spider is portia, a jumping spider. A quick search uncovers zounds of videos, articles, and scientific publications on them.

They specialize is hunting spiders, changing hunting tactics based on type and number of prey. Yes, they count. They strategize. They make multi-step plans that take them out of sight of prey. And some people keep them as pets.

addandsubtract• 21 days ago

Notice that the spider is carefully moving out of the way, just a second before the ant is launched.

It's not moving before the ant is launched. It's moving as soon as the tension in the web is gone, ie. there's movement in their web. Most spiders react to movement in their web.

optimalsolver• 21 days ago

Of course, the problem with such a high amount of specialization is that if the green ant disappears, so does this spider.

t-3• 21 days ago

I once watched a spider spinning a very crude "parachute" and catching wind to leap between two parked cars about 6 feet apart. Spiders definitely have great spatial reckoning and a level ingenuity in silk use that is pretty shocking for such small creatures.

sethammons2• 22 days ago

Amazing specialization. I was wondering the same thing. Cave glow worms cast a "fishing line," and this is similar-ish. I wonder if N million years ago, a couple of fishing-line-like spiders started anchoring their lines, and the ones with a more conic shape anchor may led to more success over time. And the anchor may have only worked on territorial prey. Fun stuff to imagine.

jcims• 22 days ago

Just saw glow worms for the first time last month. Very cool critters. Not sure I even knew they existed before that.

wazoox2• 22 days ago

There are many such mysterious mysteries in evolution. Some wasps paralyse a caterpillar of a particular species by stinging it very precisely in its nervous centres, then carries the caterpillar into the nest it previously dug out, lay its egg on the caterpillar then close the hole to never come back.

This is a completely automatic, unintelligent behaviour; if you remove the paralysed caterpillar at any point in the process the wasp simply goes on with its business (it will close its nest without any caterpillar inside, where the larva will die out from lack of food).

In the late 19th century, Jean-Henri Fabre studied these wasps (and many other strange insects) and had a copious correspondence with Charles Darwin on this very matter. His books are absolutely fascinating (ditto the letters Darwin and him exchanged).

felix-the-cat• 22 days ago

The weirdest insects I've seen in real life are these ones called Burying Beetles - they have chemoreceptors that allow them to detect the odor of a dead mouse from as far away as two miles. Then a male and female fly to it, dig a big hole, strip all the fur off of it to line the hole, then drag it down in there and raise their young together. They are also unusual in that outside of bees and ants, very few insects raise their young together from infancy to adulthood.

sejje• 21 days ago

lay its egg on the caterpillar
it will close its nest without any caterpillar inside, where the larva will die out from lack of food

...wouldn't the larva be with the caterpillar? You said that's where it lays the eggs.

prewett• 21 days ago

This sort of thing makes me think that if I were engineering a biome, this sort of specialized spider would be exactly how I would solve the problem of a species that I accidentally made too prolific. The spider is a targeted fix: only preys on the ants, and if the ant problem ever resolves itself, the spider goes away.

I think this is a case where the theory of evolution feels pretty handy-wavy and doesn't answer the mechanism of how this happens. The article even talks about "bioengineered" silk! There are certainly lots of cases of evolution, so it is clear that things do evolve, but the problems of a theory are revealed in the edge cases, and I think this spider suggests that the theory really needs a lot of work to be a robust theory. I don't think a simple gradient descent (evolving toward more fitness) has explanatory power in this case. A theory that hand-waved around edge cases like this would never fly in Physics; at best it would be considered a holding theory until a better one could be found, like dark matter.

(Plus, I think it's fun to think about bioengineering in a sci-fi, or even Babylon 5 way)

mc_maurer4• 21 days ago

Couple things here:

First, ecosystems don't work on this concept of "balance" or "problems to fix". There are ecological niches that are exploited by a species or not. We have both generalists and specialists, predators that will eat anything and predators that have specialized in a particular prey or hunting approach. The world is full of organisms with remarkably complex behaviors, the field of evolutionary biology would collapse if this sort of behavior disproved it.

Second, there's really nothing hand-wavy about how specialized behaviors evolve, and in fact there is a mountain of research in the fields of evolutionary biology and behavioral ecology that have significant explanatory power here. I would argue that you're the one being hand-wavy saying "I don't think a simple gradient descent...". Evolution is not a simple gradient descent, and no evolutionary biologist would ever argue that it is.

isomorphic_duck• 21 days ago

It might be more helpful to think of it as small changes in “genome-vector” taking place across generations of the species with the filter of it being not bad enough to cause extinction of the bespoke variation, as opposed to evolving towards more fitness as an optimisation objective. When thought of like this, one can imagine how high-dimensional the “feature”-space becomes, which leads to such intricate engineering we see in nature.

nader0913• 21 days ago

most HN would not like this answer, but here it is: god

CubicalOrange• 21 days ago

thats not an answer.

pvaldes4• 22 days ago

link to the paper here: https://news.ycombinator.com/item?id=48635929

kiproping• 22 days ago

The videos are amazing. Sadly I think theses types of adaptations make it easier for the species to go extinct since its so highly specialized.

gyanchawdhary2• 22 days ago

theses types of adaptations make it easier for the species to go extinct since its so highly specialized.

super interesting. I'm guessing because being highly dependent on a single tactic can make it difficult to adapt or course change ?

soulofmischief3• 22 days ago

As a general rule of dynamical systems, specialization is essentially the exploitation of regularity within your environment.

A highly regular environment can allow for extreme specialization because a system can predict and "expect" certain situations. This leads to much less energy expended, since maintaining stability requires energy that scales with the turbulence of a system.

If gravity is always down, you don't need to spend energy on organs that overcome gravity in other directions. Your circulatory system can use gravity to its advantage; that's why you can't just remain upside down, there's no effective mechanism to pump blood out of your brain.

If a car passes a street exactly every 2 minutes, you don't need to spend lots of time and energy figuring out when to cross. You know once a car crosses, you're good for 2 minutes. If you know the sun comes up around the same time every day, you can allow yourself a deep sleep during the night if you're in a safe place, or bloom only during the day.

Nature exploits such regularities in order to reduce the energy needed to maintain an organism or group, which creates specialization, whether on the scale of the group, on the scale of the individual, etc. This is hierarchical; your cells specialize, your organs specialize, you get training or education to specialize your skills, etc. For example, you might specialize as a software engineer, depending on the regularity of people willing to pay money for you to solve their problems, but AI comes around and suddenly you're out of a job.

The danger is that the more regularities you depend on, the less free energy your body needs to keep around and the less free energy you have to suddenly react and adapt to a new environment. If tomorrow, gravity started being up and not down, most of us would have a bad time. If those regularities are interdependent, as geological/biological cycles tend to be, a few bad conditions could unravel the entire ecosystem.

tclancy• 22 days ago

It is the year 2038. A new brand of slingshot is almost immediately removed from store shelves after multiple children receive through-and-through wounds.

enjrolas2• 22 days ago

The part from the paper which is so interesting is why the ant bites the trap in the first place. The paper suggests that the spider puts out a pheromone that attracts the ant and triggers the ant to aggressively bite the snare, but the pheromone only does this for the spider's target species, the green tree ant. The researchers watched three other ant species check out the snare, go "meh", and move on, unharmed, without showing any aggression towards the snare.

abrookewood2• 22 days ago

Yeah, that is pretty crazy. I wonder what it smells like? Has to be an enemy specific to that ant species right?

enjrolas2• 21 days ago

that's a good question -- the paper describes it triggering aggression in the ant within milliseconds of it probing the snare with its antenna. I don't know the basis for it, but that's some down-to-the-metal ant programming right there

mc_maurer4• 21 days ago

Ultimately, it's probably due to the rate of encounter with this species and the evolution of the pheromone towards the most consistent and intense response from that particular species. It's likely that a more general pheromone wouldn't induce such a consistent response, since it would be a less specific and reliable cue from the ant's perspective. So if you encounter lots of different ant species, a more general pheromone with a 50% response rate could work, but if you primarily encounter this ant species, a more specific pheromone with a 90% response rate is going to confer a greater fitness advantage.

Could be due to the rate of encounter with this species vs. other species, could also be due to the consistency of response with more general vs. specific pheromones. You start with spiders with silk/pheromones that ants are a little more aggressive towards, then variance in that chemical makeup leads to fitness advantages. If the pheromone confers a strong advantage in a specific ant,

xboxnolifes• 21 days ago

but the pheromone only does this for the spider's target species

Isn't this concluded through observational studies? Is it possible that its just not universally true, like it still impacts, idk, 0.01% of this ant's species due to gene diversity?

jimnotgym• 22 days ago

HN pedantry time:

discovered a remarkable new spider species...

Recently evolved then?

Or perhaps...

"An international team of researchers has recently discovered a remarkable spider species..."

jagged-chisel2• 22 days ago

It’s a new discovery for humans.

chrisweekly2• 21 days ago

that's precisely their point

dofm• 21 days ago

The notion of a species only really exists in the human world; it's a human concept. So the discovery of a new species is the discovery of a new classification need. It is new to science.

(At a first approximation, essentially all existing species are new on an evolutionary level — isn't it the case that something like 99.9% of all life on earth is newer than a million years old?)

NitpickLawyer• 22 days ago

Heh, for a second there this read like some of the Portiid adventures with Bianca and Fabian from Adrian Tchaikovsky's book "Children of time". If you find this kind of thing interesting and are a fan of sci-fi, I highly recommend the book.

spidercat• 21 days ago

Children of Time is one of the best books I've ever read, it's honestly amazing. It might be my all-time favorite. Seconding this recommendation!

zacharyfmarion• 21 days ago

Thirding it! This is your sign, go read it

imzadi• 21 days ago

I don't think I've been disappointed by anything from Adrian Tchaikovsky, tbh. Alien Clay and Service Model are also great.

tinyplanets• 21 days ago

Children of Time is fantastic! I ended up totally rooting for the spiders in the end.

throwup2382• 21 days ago

And the Underhill spiderlings in A Deepness in the Sky by Vernor Vinge too!

Another great book that I usually reread right before rereading Children of Time because the whole spider civilization angle is so fun.

chrisrickard• 21 days ago

Of course it’s an Australian spider

taf2• 21 days ago

this gives me children of time vibes

som• 21 days ago

I'm from where these spiders were found. The ants they're predating are an equally fascinating and super aggressive species of green weaver ants (that have other cool predators like "mimic" jumping spiders).

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

qurren• 21 days ago

"Just a quick check" ... no thanks. Bounced. Just deliver me the information when I send a request, I didn't ask to be checked.

INTPenis• 21 days ago

Speaking of clever animals, I just recently learned about the Australian birds that cause wildfires to drive out small game that they can catch.

https://www.nationalgeographic.com/animals/article/wildfires...

seethishat• 20 days ago

Some spiders seem to think, recognize people and take immediate evasive action. Contrast that with a beetle, or ant. They just keep walking along like I'm not even there.

I turned the kitchen light on once and saw a spider in the middle of the floor. It ran straight under the fridge. It would peek out occasionally to see if I was still there.

That's why spiders scare me.

AceyMan• 20 days ago

Spiders are insectivores and have little to no interest in you. That's why I love them. When you have spiders, you don't have pesty insects, in the same way that when you have cats you don't have rodents.

Newly discovered spider builds spring loaded snare to catch ants

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