(Portland, Ore.)—While working on an independent study project in a biology lab at Lewis & Clark College, Rebecca Duncan made a discovery that may someday find its way into kitchens and onto battlefields. Studying two groups of spiders that stick sand to themselves as a means of camouflage, Duncan discovered that they had developed the same hair structures that act as an adhesive.
With her research mentors, spider biologist Greta Binford and bio-inspired adhesion specialist Kellar Autumn, both biology professors at Lewis & Clark, then-junior Duncan spent the next year and a half researching the role hair morphology plays in retaining sand on the surface of spiders. A paper she wrote presenting this work will be published this week in Proceedings of the Royal Society B: Biological Sciences, one of the world’s most influential and respected science journals.
Application of this discovery could lead to improved designs for materials used for military camouflage and air filtration systems, for example, or even a Swiffer-like household dusting apparatus.
“It was exciting to take on my own question and find my own answer,” Duncan said. “Here, I had the opportunity to put into practice everything I had learned in the classroom and lab about conducting good research.”
The two spiders in question—Sicarius and Homalonychus—exhibit entertaining but vital behaviors for collecting sand on their surface such as kicking sand on their bodies or rolling around on their backs in sand. Videos show each spider’s camouflaging method.
While previous studies had suggested that fine particles associate with the dense hairs covering these spiders, none had proposed how this occurs or asked if the structure of hairs plays a role. Through high-resolution imaging, Duncan discovered a fascinating correlation between the two unrelated spider genera: Each independently evolved hairs with microscopic “hairlettes” extending from them that trap and adhere sand particles.
By determining that sand sticks better to hairs with hairlettes than to those without, Duncan concluded that the presence of tiny hairlettes in two unrelated sand-covering spiders evolved independently as adaptations, allowing the animals to perfectly match the color of their native environment.
“The sand trapping hairs on the spiders are a physical phenomenon, but we looked at the problem of how sand sticks to spiders from an evolutionary perspective which helped us come to our conclusion,” Duncan said. “I think this paper is a beautiful example of how approaching questions across scientific disciplines from an evolutionary angle can lead to insightful discoveries.”
Binford, a strong supporter of undergraduate research at Lewis & Clark, stressed that Duncan’s scientific leadership and initiative is as significant a story as the breakthrough research she spearheaded.
“Rebecca has accomplished something very rare among undergraduate students,” Binford said. “The caliber of her work easily stacks up to doctoral research projects, and to be published in such a prestigious journal this early in her career is phenomenal.”