On a vanilla plantation in northeastern Madagascar, scientists observed a huntsman spider devouring a frog in what resembled a silk woven leaf trap, according to a study published last fall. The trap had two overlapping leaves stitched at the sides with silk and a small envelope in the middle where the spider sits awaiting its prey.
The leafy hollow was one of four total structures the researchers found, suggesting that the huntsman spider creates these enclosures to lure and snare shelter seeking frogs, reports Jake Buehler for Science News. As the name suggests, some huntsman spiders do not weave a web to capture prey. Instead, they chase and actively hunt their food—except for a type of huntsman spider belonging to the genus Damastes. These huntsman spiders—their full scientific title is Sparassidae, Damastes sp.—prefer to sit and wait in traps they built for the kill.
“We also think that there is systematic trapping,” study co-author Thio Fulgence, a researcher at the University of Antananarivo in Madagascar, tells Joshua Rapp Learn of New Scientist. These traps are built to resemble a safe haven for frogs seeking shelter from predators and relief from the balmy Madagascar weather, explains another study author Dominic Martin, a University of Göttingen Ph.D. student, to New Scientist.
Spiders have used their silk as an incredible hunting tool for over 400 million years. At least 45,000 different spider species exist around the world, and while not every spider builds a web, each makes silk. Orb-weaving spiders use silk to construct intricate traps for insects; Bola spiders dangle a single silk thread like a lure; and other spider species prefer to use their silk as a tool to build daytime retreats or wrap their prey.
However, only a single observation of the spider eating a frog near the trap was reported in the study, and it has sparked some debate among scientists not involved in the research. Behavioral biologist Stano Pekar from Masaryk University explained to Science News that it is a possibility that these spiders are not hunting frogs specifically but hiding in the retreats that they built and attacking any prey that happens to pass by.
Conservation biologist Jose Valdez from the German Centre for Integrative Biodiversity Research understands the skepticism, but says it’s certainly a lot of work to go through to conceal oneself. There’s no shortage of corners and crevices to crawl into in a forest.
“What makes me think otherwise is that not only did the researchers find the leaf retreats multiple times, but the spider was weaving the edges of the leaves,” Valdez tells Science News.
The study’s authors are quick to note this actually isn’t the first reported instance of a spider eating a frog in Madagascar. They hope their study can be a starting place for looking into other examples of vertebrae predation in huntsman spiders.