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Spiders Can Catch and Devour Fish [Slide Show]
Entomologists confirm fish-eating spiders are widespread and wily
Spiders Can Catch and Devour Fish [Slide Show]
Leggy Luncheon Visitor Give a spider a fish and it will feast for hours. Teach a spider to fish, however, and you are probably just wasting your time—it turns out many species are already more than proficient. Take for example this specimen from the voracious fishing spider family, Dolomedes, which has captured a pond fish in a garden near Brisbane, Australia.
Credit: Photo by Peter Liley, Moffat Beach, Queensland. Courtesy of Martin Nyffeler, University of Basel
Mighty Mouthful To get a sense of just how common fish-eating spider events are, researchers Martin Nyffeler, an entomologist at the University of Basel in Switzerland, and Bradley J. Pusey, an ecologist at the University of Western Australia, pored through scholarly journals, photos and other documentation to develop a more comprehensive understanding of fish predation by spiders. They found that these events occur on every continent except Antarctica and that spiders typically nab prey more than twice their size. Here an adult male Ancylometes spider in Ecuador carries off a fish dinner.
Credit: Photo by Ed Germain, Sydney, Australia. Courtesy of Martin Nyffeler, University of Basel
All in the Technique Certain species of semiaquatic spiders can dive, swim and walk on top of the water. When capturing bugs, these arachnids typically dangle their legs atop the water’s surface, waiting for changes in surface tension much as they would the vibrations on a web. But to catch a fish, their approach is more direct. In laboratory experiments, as soon as their swimming prey hits a spider’s outstretched leg, the predator lunges and takes a bite. The venom, packed with potent neurotoxins, can finish off a small organism within seconds. This spider from the Trechalea genus is tugging its prey up from a stream in Colombia.
Credit: Photo by Juan Esteban Arias A., Cali, Colombia. Courtesy of Martin Nyffeler, University of Basel
High and Dry Spiders have to pull their prey out of the water to consume them. This is because to eat, spiders must first pump enzymes, which would be diluted underwater, into their quarry’s body to break down tough tissues. Once accomplished, a spider can essentially slurp up its catch. Here a Trechalea spider in Colombia enjoys a hard-earned feast on a rock in the middle of a small river.
Credit: Photo by Solimary Garcia Hernandez, Instituto de Biociências, Universidade de São Paulo, Brazil. Courtesy of Martin Nyffeler, University of Basel
Such Great Heights In total, the entomologists identified five spider families that capture and consume fish in natural conditions. They presented a full list of their findings in PLoS One on June 18. “The fact that spiders from many different families are catching fish was very surprising to me,” Nyffeler says. The spiders’ skills are nontrivial. In the image above a Ctenid spider carries a fish up into the branches above the Tahuayo River in Peru.
Credit: Photo by Alfredo Dosantos Santillán c/o Amazonia Expeditions, Tampa. Courtesy of Martin Nyffeler, University of Basel
Snagged Nyffeler, who has previously studied spider predation of bats, explains that, generally speaking, vertebrates are still a small part of the spiders’ diets. For those arachnids lucky enough to enjoy a fish dinner, however, the meal provides far more protein and energy than the typical insect snack. This could explain the seeming contentment of this spider from the Pisaurid family in Cameroon, despite having been caught in a human fishing net.
Credit: Photo by Duncan Reid, Yale University. Courtesy of Martin Nyffeler, University of Basel
One Man's Bait Is a Spider's Dinner Most fish-eating spider reports come from the eastern U.S. Here, for example, a Dolomedes spider has just snagged some bait fish after a fisherman’s bad cast on a dock in Maine. Nyffeler and Pusey believe the number of reports in this region reflects the high population of nature watchers and ecological researchers in these areas.
Credit: Photo by Jeffrey Hollis, East Haddam, Conn. Courtesy of Martin Nyffeler, University of Basel
All You Can Eat Big Cypress National Preserve in Florida is home to many fishing spiders, such as the one shown here. A popular non-insectean target for Floridian semiaquatic spiders is the common mosquito fish, an abundant surface-feeder, but these spiders are also known to snag the occasional frog.
Credit: Photo by Misti Little, Stagecoach, Texas. Courtesy of Martin Nyffeler, University of Basel
Northern Exposure Most reports of fish-eating spiders come from between latitudes 40 degrees south and north of the equator, meaning these fishing spiders primarily inhabit places with warmer climes. There are exceptions, however, as this Dolomedus scriptus spider hauling up a sunfish in Ontario illustrates.
Credit: Photo by Lloyd Alter, Toronto, Canada. Courtesy of Martin Nyffeler, University of Basel