Warning for arachnophobes and the faint of the heart:
The University of Michigan led by biologists has documented 15 rare and disturbing predator-pre-interactions in the Amazon rainforest.
"Ecological interactions between arthropods and small vertebrates in a lowland Amazon rainforest." Arthropods are invertebrate animals with segmented bodies and joint appendages that include insects, arachnids (spiders, scorpions, mites and ticks) and crustaceans.
The article, scheduled for online publication Feb. 28 in Amphibian & Reptile Conservation, details of the arthropod predators – most large spiders along with a few centipedes and a giant water bug – preying on vertebrates such as frogs and tadpoles.
"This is an underappreciated source of mortality among vertebrates," said Daniel Rabosky, evolutionary biologist at the University of Michigan. "A Surprising Amount of Deaths in the Amazon"
Once a year, Rabosky leads a team of U-Med (faculty members, postdocs, graduate students and undergraduates) and international collaborators on the Madre de Dios region of southeastern Peru.
The study site, in the Lowland, is the foothills of the rainforest and the most diverse ecosystems on the planet. The team's main research focus is the ecology of reptiles and amphibians. But over the years, scientists have witnessed and documented numerous interactions between arthropod predators and vertebrate prey.
"We kept recording these events," said Rabosky, an associate professor at the Department of Ecology and Evolutionary Biology. Zoology.
Spiders are among the most diverse arthropod predators in the tropics, fish, amphibians, reptiles, birds and mammals.
However, it is not the case that these types of interactions are limited, especially in the case of species-rich tropical communities. The new paper includes observations from 2008, 2012, 2016 and 2017.
"The study's first author, Rudolf von May, is a postdoctoral researcher. in Rabosky's lab.
"Where we do this is about 85 species of reptiles – and about 90 species of reptiles," von May said. "May May."
In addition to the Los Amigos Biological Station, other observations were made at the Villa Carmen Biological Station, also in the province of Madre de Dios, and at the Madre Selva Research Station in the Loreto region of northern Peru.
Nearly all of the sightings were made at night, when the arthropod predators are most active. During their night surveys, team members walk slowly through the forest with flashlights and headlamps.
During one of those night surveys, U-M doctoral candidate Michael Grundler and two other students "heard some scrabbling in the leaf litter."
"We looked over and we saw a large tarantula," said Grundler, a co-author of the paper. "The opossum had been grasped by the tarantula and was still struggling at that point, but after about 30 seconds it stopped kicking." The tarantula was a dinner plate, and the young mouse opossum was about the size of a softball. Grundler's sister Maggie pulled out her cell phone and shot photos and some videos.
Later, an opossum expert at the American Museum of Natural History. The infraorder Mygalomorphae is a group of mostly heavy-bodied, stout-legged spiders that includes tarantulas.
"We were pretty ecstatic and shocked, and we couldn't really believe what we were seeing," Michael Grundler said. "We knew we were witnessing something pretty special, but we weren't aware of it."
Most predaceous arthropods rely on specialized body parts and venom to capture and paralyze vertebrate prey. These adaptations include modified jaws, enlarged beaks and massive fangs. Some groups have evolved dosens of venom proteins that are injected during prey capture.
Other predator-prey interactions documented in the Amphibian & Reptile Conservation paper include:
Several examples of large spiders of the family Ctenidae preying on frogs and also a lizard. Most of the predictions are documented in the paper, which are known as wandering spiders. Ctenid spiders are sit-and-wait predators that hunt at night and use their hair. Their principal eyes are responsible for object discrimination, and secondary eyes detect motion.
A large scolopenders for centipede consuming a live Catesby's snail-eater snake, and another centipede eating a dead coral snake that it had decapitated. "Coral snakes are very dangerous and can kill humans," said Joanna Larson. Those centipedes are terrifying animals, actually. "
Amazing frogs and commensal relationships between spiders and frogs. The commensal relationship is one in which the other is not harmed.
"One of the coolest things about working in Peru," said Larson, who studies the evolution of diet in the frogs. "Every day you see something new and exciting."
She said, "One offshoot of the work that we've been doing. "I have not got the level of being grossed out by any of it yet. We'll see what else Peru has to offer."
The other authors of the paper, in addition to Rabosky, von May, Michael Grundler and Larson, are Emanuele Biggi of the International League of Conservation Photographers; Heidy Cárdenas and Roy Santa-Cruz of the Museo de Historia Natural de la Universidad Nacional de San Agustín, Peru; M. Isabel Diaz of the Universidad Nacional de San Antonio Abad del Cusco and Museo de Biodiversidad del Perú, both in Peru; Consuelo Alarcón of John Carroll University of the Biodiversidad del Perú; Valia Herrera of the Universidad Nacional Mayor de San Marcos, Peru; Francesco Tomasinelli of Milan, Italy; Erin P. Westeen and Maggie R. Grundler of the University of California, Berkeley; Ciara M. Sánchez-Paredes of the Universidad Peruana Cayetano Heredia, Peru; and Pascal O. Title and Alison R. Davis Rabosky of the U-M Museum of Zoology and the Department of Ecology and Evolutionary Biology.
The Wildlife Conservation Society, The Rosemary Grant Award, The Edwin C. Hinsdale UMMZ Scholarship, and the University of Michigan .