Researchers document every step of spider-web building
From:
Johns Hopkins University
November 1, 2021 -- Johns Hopkins
University researchers discovered precisely how spiders build webs by using
night vision and artificial intelligence to track and record every movement of
all eight legs as spiders worked in the dark.
Their creation of a web-building
playbook or algorithm brings new understanding of how creatures with brains a
fraction of the size of a human's are able to create structures of such
elegance, complexity and geometric precision. The findings, now available
online, are set to publish in the November issue of Current Biology.
"I first got interested in this
topic while I was out birding with my son. 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 behavior occurs," said senior author Andrew
Gordus, a Johns Hopkins behavioral biologist. "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."
Web-weaving spiders that build blindly
using only the sense of touch, have fascinated humans for centuries. Not all
spiders build webs but those that do are among a subset of animal species known
for their architectural creations, like nest-building birds and puffer fish
that create elaborate sand circles when mating.
The first step to understanding how the
relatively small brains of these animal architects support their high-level
construction projects, is to systematically document and analyze the behaviors
and motor skills involved, which until now has never been done, mainly because
of the challenges of capturing and recording the actions, Gordus said.
Here his team studied a hackled orb
weaver, a spider native to the western United States that's small enough to sit
comfortably on a fingertip. To observe the spiders during their nighttime
web-building work, the lab designed an arena with infrared cameras and infrared
lights. With that set-up they monitored and recorded six spiders every night as
they constructed webs. They tracked the millions of individual leg actions with
machine vision software 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."
They found that web-making behaviors are
quite similar across 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.
"Even if the final structure is a
little different, the rules they use to build the web are the same,"
Gordus said. "They're all using the same rules, which confirms the rules
are encoded in their brains. Now we want to know how those rules are encoded at
the level of neurons."
Future work for the lab includes
experiments with mind-altering drugs to determine which circuits in the
spider's brain are responsible for the various stages of web-building.
"The spider is fascinating,"
Corver said, "because here you have an animal with a brain built on the
same fundamental building blocks as our own, and this work could give us hints
on how we can understand larger brain systems, including humans, and I think
that's very exciting.
Authors also include Nicholas Wilkerson,
a former Hopkins undergraduate and current graduate student at Atlantic
Veterinary College, and Jeremy Miller, a graduate student at Johns Hopkins.
https://www.sciencedaily.com/releases/2021/11/211101105356.htm
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