Spiders, like octopuses, have eight legs. But they also share something else – like octopuses, once we got down to studying them, they turned out to be much smarter than expected. What makes spiders even more unusual is that they are intelligent with a very small brain:

“There’s this general idea that spiders are probably too small, that you need some sort of 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 a case where that general idea is challenged. Some little things are actually able to do very complex things.

Behaviors that can be described as “cognitive,” as opposed to automatic responses, might be quite common among spiders, says Dimitrov, co-author of a study on spider diversity published in the 2021 Annual Review of Entomology. From orb-weavers that adjust the way they build their webs based on the type of prey they catch, to ghost spiders that can learn to associate a reward with the scent of vanilla, there’s more going on in the brains of spiders than they usually think.

BETSY MASON“SPIDERS ARE MUCH SMARTER THAN YOU THINK” AT KNOWING MAGAZINE (OCTOBER 28, 2021)

There are other life forms where the idea that brain size is a guide to intelligence is challenged. For example, lemurs, whose brains are 1/200 the size of a chimpanzee’s brain, can pass the same IQ test.

Very intelligent hunting behavior

But, as Mason reports, jumping spiders, for example, can show very intelligent hunting behavior. A group of jumping spiders, Portia, lure female spiders of another species (Eurytattus) to their death by mimicking the way a courting male spider shakes its nest and then attacks. They also attack web-building spiders by mimicking the tug on a trapped insect’s web, adjusting its tug to the size of the spider it plans to devour. More remarkably,

If these strategies don’t work on a particular spider’s web, another Portia trick is to shake the entire web so that it moves as if a gust of wind has hit it. This acts as a smokescreen for the vibration Portia makes as she crawls through the target spider web. In lab experiments, Jackson discovered that Portia would try different picking methods, speeds, and patterns until she found the right combination to fool every web spider she hunted—essentially by learning on the job.

BETSY MASON“SPIDERS ARE MUCH SMARTER THAN YOU THINK” AT KNOWING MAGAZINE (OCTOBER 28, 2021)

Portia spiders have big brains – compared to other spiders – but that’s probably not the complete answer to how they develop so many clever strategies. organization of the brain is probably a factor as well.

Another recent discovery is that the bridge spider, Larinioides sclopetarius, transforms his canvas into a giant ear, to hear over great distances:

According to a preprint study published on biologicalRxiv October 18. The discovery, which has not yet been peer-reviewed, challenges many assumptions scientists have held for years about how spiders and potentially other arthropods navigate and interact with the world around them.

“From an evolutionary perspective, spiders are just weird animals,” Jessica Petko, a Pennsylvania State University biologist at York who didn’t work on the new study, writes in an email to The Scientist. “Although spiders have long been known to sense sound vibrations with sensory hairs on their legs, this paper is the first to show that orb-weaving spiders can amplify that sound by building specialized web-like structures.”

DAN ROBITZSKI“SPIDER USES HIS WEB AS A GIANT ENGINEERED EAR” AT THE SCIENTIST, (OCTOBER 29, 2021). THE PAPER IS FREE TO ACCESS.

Some spiders have also mastered the art of hunt in packs.

Read more on The mind matterspublished by the Bradley Center for Natural and Artificial Intelligence at the Discovery Institute.