It’s a Halloween mystery — one that astonished even Charles Darwin.
On Oct. 31, 1832, thousands of tiny red spiders dropped from a clear sky onto Darwin’s ship, the HMS Beagle. Baffled, the young biologist noted that winds were calm. Spiders don’t have wings. And they weren’t dumped by migrating birds. So how did they travel 60 miles, over water, from the Argentine coast to land on the deck of the Beagle?
The evolutionist labeled the invasion “inexplicable.” Which, for almost two centuries, it was. Enter computer modeling.
“Our method allows us to perform 3D simulations, where we show the shape of threads during ballooning,” says M. Khalid Jawed, an assistant professor of mechanical and aerospace engineering at the UCLA Samueli School of Engineering. “It’s an amazing process to watch.”
The “method” Jawed is talking about is a new one developed by UCLA researchers, who are now repurposing Hollywood effects so scientists can more fully understand how spiders escaping predators can soar two miles up into the air and then “balloon” hundreds of miles from home. The emerging answers may influence the design of everything from biometric robots to NASA rovers on Mars.
Working with Professor Charbel Habchi of Notre Dame University Louaize in Lebanon, Jawed has used computer modeling to illustrate how spiders shoot webs into the air, where the silk is then “powered up” by the earth’s electrical field. Not only does the force give spiders both lift and direction, but it also prevents the webs — sometimes dozens of meter-long threads — from becoming entangled with one another. The findings challenge the traditional scientific view that spiders are blown around the world, although aerial currents do play a part.
Jawed has long been fascinated by the scientific puzzle presented by Darwin’s question. The “aha” moment about spiders — and Darwin’s odd encounter with them — came after scientists adapted a computer simulation algorithm called Discrete Elastic Rods, originally developed by the computer graphics community for movie animation.
All of which has Jawed’s own Spidey sense tingling about what other discoveries may still lie ahead. “We have,” he says, “so much to learn from nature.”
Read more from UCLA Magazine's July 2022 issue.
