Biology

This Wily Spider Can Hide Out Underwater for a Whopping 30 Minutes

Guess that's good news?

Tropical spider Trechalea extensa maintained a film of air around its body while submerged for 30 minutes.
Lindsey Swierk

There are certain places I expect to encounter spiders. In the corners of rooms. Under benches outside. In the branches of shrubs. But underwater? That's a new one. Biologist Lindsey Swierk of Binghamton University in New York observed a spider hiding out underwater for a remarkable 30 minutes. 

The impressive spider was fleeing from humans and used a stream as a refuge. Swierk is the lead author of a paper on the spider's diving behavior published in the journal Ethology last month.   

According to the World Spider Catalog, Trechalea extensa is distributed from Mexico to Panama and lives along streams. A 1993 study describing the spider said "they bite readily the collector's hand." But we're not here for nibblings. We're here for the spider's submerged survival prowess.

"For a lot of species, getting wet and cold is almost as risky to survival as dealing with their predators to begin with," Swierk said in a Binghamton statement on Monday. "Trechalea spiders weren't previously known to hide underwater from threats -- and certainly not for so long."  

The secret to the spider's watery success seemed to be a surrounding "film" of air held in place by hydrophobic body hairs. Swierk described the spider as looking like it had been dipped in silver and suggested the film might work to keep its respiratory openings away from water and perhaps reduce heat loss from the cold stream.

The arachnid's underwater expedition was an extreme measure aimed at avoiding a perceived threat. Further observations of the spider's unusual behavior could help scientists better understand how the animals deal with predators. And I might start keeping an eye on spider activity in my backyard pond. Just in case.