JAY STAFSTROM: Hi, I'm Jay Stafstrom, and I work on some of the coolest spiders on the planet. These ogre-face, net-casting spiders that we worked on for this paper not only have unique and fascinating foraging behavior, but they also have some really cool sensory systems that are well adapted for allowing them to capture prey in their own net casting method.
The species that we actually looked at is Deinopis spinosa. And you can find them here in Florida or scattered across the southeastern US.
So these spiders are nocturnal. They do nothing during the day but hide and wait until sunset. When these spiders come out at night, they exhibit some extraordinary hunting behavior that's totally unique to this family of spider.
And what they do is they'll make a frame web that kind of looks like the letter A out of non-sticky silk. And then within that frame, they'll make a fuzzy rectangular net that they hold with their front four legs. And they'll actively ensnare prey with this net.
They can catch prey with this net both with prey items moving beneath them, like walking on the ground beneath their frame web. They can do a forward strike is what it's called when they're lunging downward and tackling prey that way. Or if an insect is flying above or close by, they can actually spring up backward, and that's called the "backwards strike," and catch things out of the air that way.
Ogre-faced spiders, from the genus Deinopis, have the biggest eyes of any spider . And they're hypersensitive to light, obviously, useful in their nocturnal foraging habits. And that's something that I specifically have shown not so long ago, that when you visually occlude their enlarged eyes, they're no longer able to capture prey walking beneath them when you put them back out in nature and let them do their thing.
But those same spiders can still catch things out of the air just fine. And so that finding actually backs up previous research that hypothesized that these spiders can actually hear prey that they're catching with their backwards strike. That's something that we wanted to further investigate. Can they actually hear from a distance, what can they hear, are they more sensitive to specific frequencies, stuff like that. Yeah, and that's what this paper is about.
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Slow motion video shows how the ogre-faced, net-casting spider catches its prey at night. Cornell University postdoctoral researcher Jay Stafstrom narrates the footage recorded in Florida.