# Spiders Are Much Smarter Than You Think - Real Title: Spiders Are Much Smarter Than You Think - [ ] #pkm/synthesize with [[how spidersilk is harvested]] and [[yhaoginli]] ## Highlights ### id260586402 brain size might not always correlate to behavioral complexity > There is this general idea that probably spiders are too small, that you need some kind of a critical mass of brain tissue to be able to perform complex behaviors,” says arachnologist and evolutionary biologist Dimitar Dimitrov of the University Museum of Bergen in Norway. “But I think spiders are one case where this general idea is challenged. - [View Highlight](https://read.readwise.io/read/01fqd2sgt4baeh68d41hsgh412) > Jumping spiders are not the biggest spiders, but they are probably able to perform the most complex behaviors among spiders, Dimitrov says. “So I think we still don’t really understand what is the threshold, how small is too small.” - [View Highlight](https://read.readwise.io/read/01fqd376gzd6matdpnqxetsmzx) ### id260586412 spiders are clever > Behaviors that can be described as “cognitive,” as opposed to automatic responses, could be fairly common among spiders, says Dimitrov, coauthor of a study on [spider diversity](https://www.annualreviews.org/doi/full/10.1146/annurev-ento-061520-083414) published in the 2021 *Annual Review of Entomology*. From [orb weavers](https://knowablemagazine.org/article/living-world/2018/sticky-science-evolution-spiderwebs) that [adjust the way they build their webs](https://www.jstor.org/stable/2390229) based on the type of prey they are catching to ghost spiders that can learn to associate a reward [with the smell of vanilla](https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1570-7458.2008.00669.x), there’s more going on in spider brains than they commonly get credit for. - [View Highlight](https://read.readwise.io/read/01fqd2sxpag5f7q64hnvmyrpys) ### id260586422 jumping spiders are the smartest spiders > Cross studies the behavior of jumping spiders, the undisputed champs of cognition among spiders. Although these tiny arachnids have brains that could literally fit on the head of a pin, the work of Cross and other scientists suggests that they have capabilities we’d have no problem hailing as signs of intelligence if exhibited by animals with much larger brains, like dogs or human toddlers. - [View Highlight](https://read.readwise.io/read/01fqd2tdnjww53c3aa01hd28c0) ### id260586517 vision may correlate to intelligence > One possible reason jumping spiders are so behaviorally advanced is that they have the sharpest vision known for animals their size, which is typically just 1 millimeter to 2.3 centimeters in length. They use this visual prowess to find, stalk and pounce on their prey, rather than the better-known spider strategy of building a web and waiting for a meal to arrive. - [View Highlight](https://read.readwise.io/read/01fqd2xcnbze9rsdcgr94hj2av) ### id260586519 Portia spiders are devious hunters > The jumping spiders shown to have the sharpest eyesight and the most impressive smarts belong to the genus *Portia*, found in Africa, Asia and Australia. These spiders prefer to hunt other spiders and have strategies tailored to each species they prey upon. Renowned University of Canterbury jumping spider researcher Robert Jackson has discovered that many of [*Portia*’s tactics are quite devious](https://www.annualreviews.org/doi/abs/10.1146/annurev.en.41.010196.001443). - [View Highlight](https://read.readwise.io/read/01fqd2xx00hxxjvscq7ktycde8) ### id260586564 Portia spiders make contextual decisions > For *Portia*, finding the right strategy is especially important when pursuing spiders that also eat jumping spiders. To attack a web-building spider, for example, *Portia* deceives the spider into moving closer by plucking some of the silk strands of its web. If the target spider is relatively small, *Portia* plucks the web to mimic a trapped insect, prompting the spider to rush over thinking it’s about to have a meal — only to become one instead. But if the resident spider is bigger and potentially more dangerous, *Portia* may instead create a gentle disturbance similar to a fruit fly contacting a single strand at the edge of the web that the spider will slowly wander over to inspect. As soon as the target is close enough, *Portia* pounces and strikes with venomous fangs - [View Highlight](https://read.readwise.io/read/01fqd2zgd158xdvtf073027hmd) ### id260586568 Portia spiders experiment > If these strategies don’t work on a particular web spider, another of *Portia*’s tricks is to shake the whole web so it moves as if a gust of wind had hit it. This acts as a smokescreen for the vibration *Portia* makes as it crawls into the target spider’s web. In laboratory experiments, Jackson found that *Portia* will try different plucking methods, speeds and patterns until it finds just the right combination to fool each individual web spider it hunts — essentially [learning on the job](https://www.jstor.org/stable/4535141). > > “Even amongst this surprisingly intelligent group, *Portia* stand out as being oddly brilliant,” Morehouse says. “They are, after all, hunting very dangerous prey, so caution and cleverness are useful tools.” - [View Highlight](https://read.readwise.io/read/01fqd302nzjazg4nkr5185dv0x) ### id260586571 spiders can plan > One of the most fascinating aspects of *Portia*’s hunting strategy is that it often involves spotting prey from a distance and then planning out an elaborate route to get to it. Jackson first observed this in the wild when *Portia* encountered a species of orb weaver that [defends its web by violently shaking it](https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-7998.1992.tb04451.x), tossing any invading jumping spiders to the forest floor. Instead of entering the web, *Portia* navigated a roundabout path to find a better position from which to attack. “In that context, it was better for *Portia* to take the detour, go around the tree trunk, go up above the spider, go down on a line of silk, and swing in, grab the spider in its web without even touching the silk,” Cross says. > > Cross and Jackson argue that the spiders [planned the route](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4751061/) from the viewing tower and then followed it, possibly by forming a mental “representation” of the scene — an impressive cognitive feat for a brain barely bigger than a poppy seed. - [View Highlight](https://read.readwise.io/read/01fqd31yrwgh4e1qmkdm64a0ke) ### id260586720 spiders can be surprised > The scientists discovered that if *Portia* saw a different kind of prey after the shutter was lifted, it was far less likely to attack than if the prey remained the same. They assert that this shows that the spider [formed a mental representation](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3946049/) of the prey at the beginning of the trial that didn’t match what it saw at the end. - [View Highlight](https://read.readwise.io/read/01fqd344ba22vhaekthkx360gn) ### id260586765 Portia spiders have good number sense > This is how they discovered [*Portia* is good with numbers.](https://royalsocietypublishing.org/doi/full/10.1098/rsfs.2016.0035) Using a species from Kenya, *Portia africana*, Cross and Jackson let *Portia* see a number of prey items from the viewing tower, and then switched up the number of prey items while the spider was en route and the target was out of sight. They found that if *Portia* had seen one prey spider from the tower but arrived to find two spiders, it was less inclined to carry out an attack. The same was true for one versus three prey items, and two versus three, and also when it encountered only one item after initially having been shown two or more. When tested with larger quantities, the spiders didn’t distinguish between three or higher, lumping them all into one category of “many.” > > Although spiders can’t literally count one-two-three, the research suggests some jumping spiders have a sense of numbers roughly equivalent to that of [1-year-old humans](https://onlinelibrary.wiley.com/doi/abs/10.1111/1467-7687.00313). - [View Highlight](https://read.readwise.io/read/01fqd3532r84f0qfnrgnb931cf) ### id260586996 time planning correlates positively with safety > The only catch is that it can take *Portia* quite a while to complete tasks like these — sometimes several hours — and usually much, much longer than other jumping spiders that Nelson tested, she says. Nelson found a clear relationship between the time a spider spent surveying the route and the likelihood of choosing a safe path. “Seeing is thinking, in my view,” she says. “*Portia* spent a lot more time looking at the route before making a decision.” - [View Highlight](https://read.readwise.io/read/01fqd36nd814pdw77bezbx2gwh)