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Sandy Spiders

February 14, 2008

Researchers discover how a spider renders itself nearly invisible using a coat of sand.


Spiders find safety in sand. I’m Bob Hirshon and this is Science Update.

Six-eyed sand spiders look just like the sand they live on. That’s because the spiders roll in the sand and cover themselves with it. But instead of falling off, the sand can stay attached for months, even years, until the spider moults off its outer layer. Biologists Rebecca Duncan and Greta Binford at Lewis & Clark College in Portland, Oregon looked at the spiders through a powerful electron microscope. Binford says they found tiny hairlettes on the bristles covering the spiders’ bodies.

GRETA BINFORD (Lewis & Clark College):
Hairlettes are these protrusions that are long and flexible. And it’s clear that these hairlettes have an ability to capture and retain sand and hold it for a long period of time.

She says weak molecular forces are probably responsible for holding the sand in place. She adds that while the scientists don’t yet know what eats the spiders, the sand probably serves as camouflage against predators. I’m Bob Hirshon for AAAS, the science society.