Even people who aren’t fans of spiders can appreciate the intricate beauty of their webs. It’s even more fascinating when you consider the fact that the arachnids have tiny brains, yet somehow can build these geometrically precise creations.
Now, scientists at Johns Hopkins University have used artificial intelligence and night vision to establish how exactly spiders build their webs.
“I first got interested in this topic while I was out birding with my son,” said senior author Dr Andrew Gordus, a Johns Hopkins behavioural biologist.
“After seeing a spectacular web I thought, ‘if you went to a zoo and saw a chimpanzee building this you’d think that’s one amazing and impressive chimpanzee’. Well, this is even more amazing because a spider’s brain is so tiny and I was frustrated that we didn’t know more about how this remarkable behaviour occurs. Now we’ve defined the entire choreography for web-building, which has never been done for any animal architecture at this fine of a resolution.”
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First, the scientists had to systematically document and analyse the behaviours and motor skills involved.
They took six hackled orb weaver spiders, which are small, nocturnal spiders native to the western United States. They selected this spider species as they do not need humid conditions, and can happily co-exist with each other.
In the lab, each spider was placed on a plexiglass box, under an infrared light. Each night, the spiders were recorded using a camera that operated at a fast frame rate, to capture all of their tiny movements as they built their webs.
The researchers then tracked the millions of individual leg actions with an algorithm designed specifically to detect limb movement.
“Even if you video record it, that’s a lot of legs to track, over a long time, across many individuals,” said lead author Abel Corver, a graduate student studying web-making and neurophysiology. “It’s just too much to go through every frame and annotate the leg points by hand, so we trained machine vision software to detect the posture of the spider, frame by frame, so we could document everything the legs do to build an entire web.”
Researchers found that web-making behaviours are quite similar across individual spiders, so much so that the researchers were able to predict the part of a web a spider was working on just from seeing the position of a leg. They think that the algorithm would work for other species of spiders, and would like to explore this in the future.
The researchers think that the findings could offer hints on how to understand larger brain systems in other animals, including humans. Other future experiments will involve using mind-altering drugs to establish which circuits in a spider’s brain are responsible for web-building.
“Spider webs are one of the most amazing of nature’s constructions, unless you’re a fly of course,” said Prof Adam Hart, an entomologist who was not involved in the research. “By being able to follow every tiny movement this research is finally unlocking the complex ‘dance’ spiders do to make their webs. We can learn so much from nature, and research like this can give us all sorts of insights into how we can make new materials and structures.”
Reader Q&A: Are spiders scared of conkers?
Asked by: Jack Roberts, Cheshire
Putting conkers around the house to deter spiders is an old wives’ tale and there’s no evidence to suggest it really works. Spiders don’t eat conkers or lay eggs in them, so there is no reason why horse chestnut trees would bother to produce spider-repelling chemicals. There is no hard research on the subject, but pupils of Roselyon Primary School in Cornwall won a prize from the Royal Society of Chemistry in 2010 for their informal study showing that spiders were unphased by conkers.
Spiders are most common indoors in the autumn months. At this time of year, male house spiders leave their webs and start wandering in search of females. If you hoover up all the spiders in your house, it will probably take a couple of weeks for the spiders to recolonise – regardless of whether or not you scatter conkers around the place.