What spiders eat strange things tell us about complex food networks of Amazon


Rudolf von May has seen some pretty wild things in the Amazon rainforest of Peru. But it took things to a whole new level. On the video of a member of the team, there was a giant, plate-sized tarantula that was wavering in leaf litter with the body of what was later identified as an opossum of mouse hooked to his fangs.

"It was very surprising, to some extent shocking," says von May, an ecologist at the University of Michigan at Ann Arbor, about the first record of such a meeting. "It is very rare to see mammals being attacked by a big spider."

Along with his colleagues, von May has been making regular trips of three to four weeks in the rainforest for at least 10 years. Each night, the team splits into groups and scours the thick moisture and biting insect clouds to collect data on amphibians and reptiles – from counting creatures to sampling. 39, tissue samples.

They also discovered some surprising information about who eats who. From 2008 to 2017, the team documented 15 cases of invertebrates feeding on vertebrates. These encounters included everything from a wandering spider clinging to a bolivian Bolivian frog to a centipede eating a juvenile, extremely poisonous coral snake that she had decapitated. And, of course, there was the breathtaking tarantula vs. opossum. The results were published on February 28 in Conservation of amphibians and reptiles.

SHOCK SCENE When researchers working in the Peruvian rainforest heard grinding leaves, they lit their flashlights and witnessed something never documented before: a plate-sized tarantula (Pamphobeteus sp. ) Trailing an opossum of young mice (Marmosops noctivagus) he had killed.

"It is very valuable and necessary to document these interactions in the field, as tropical ecosystems are extremely diverse," says von May. This biodiversity makes it difficult to know exactly how organisms touch each other. Scientists have known since at least the 1980s that invertebrates, which often have vibration-detecting hairs or paralyzing venom, play a crucial role in vertebrate consumption.

But the frequency and diversity of such interactions remain uncertain. "We just have very limited knowledge," says von May. Now, at least, it is becoming increasingly clear that the Amazonian food web is vast and complex.

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