Biologist Brian Gall was flinging stowaway spiders out of his kayak when he noticed an interesting pattern: After landing on the water’s surface, the arachnids quickly darted to the nearest shoreline, no matter how far he paddled from dry land.
Scientists have studied the navigation skills of only a handful of the approximately 51,000 known species of arachnids. Spiders have been shown to rely on sound, vibrations, chemical signals and, of course, their eight eyes (SN: 10/29/20). Some species can see and use polarized light, which can occur naturally when light waves flatten as they reflect off a surface such as water.
“Spider vision is completely different than ours,” says Sidney Goedeker, who worked with Gall as an undergraduate and is currently a research technologist at the University of Louisville in Kentucky. “And it’s not something that we can perceive because we don’t have what they have.”
Perhaps, Gall thought, the stowaways could offer a way to study the elongate stilt spider’s homing senses. His team built test arenas in an outdoor tank and a natural pond in Gall’s backyard, using a film suspended over the water to polarize incoming sunlight before it hit the surface, creating areas without glare that mimicked what land might look like to a spider. Then, the researchers dropped 68 spiders into the arenas and recorded their movements.
2023-12-19 11:30:00
Source from www.sciencenews.org