Researchers of a new study found that arthropods are actually a significant cause of mortality among small vertebrates in the rainforest. In the Amazon, many of these deaths are due to predation by large spiders and centipedes.

Predator Spider

A team of researchers traveled to the Madre De Dios region of the Amazon rainforest in southeastern Peru to survey predator-prey relationships in the Amazon rainforest. They conducted most of their surveys at night during which they scoured the forest with flashlights and headlamps. They did this because arthropod predators are most active at night.

Among their finds is a one-of-a-kind event when they chanced upon a large tarantula preying on a young mouse opossum. The opossum was still struggling weakly even with the tarantula grasping its neck then, but it eventually stopped kicking after about 30 seconds.

Evidently, what they captured was the first documentation of a mygalomorph spider preying on an opossum, as confirmed by an experts from the American Museum of Natural History. According to researchers, while they knew that what they were witnessing was special, at the moment they were unaware that it was the first observation.

Predator-Prey Interactions In The Amazon Rainforest

During their survey, researchers found arthropods such as spiders and centipedes preying on vertebrates such as frogs, lizards, and even snakes and small opossum. For instance, they observed several large spiders preying on frogs and lizards, and they even observed a large centipede eating a live Catesby’s snail-eater snake and another centipede eating a coral snake it had already decapitated.

Describing it as an “underappreciated” mortality source among vertebrates, the researchers say that this shows that a surprising amount of deaths in small vertebrates can likely be attributed predation by arthropods such as spiders and centipedes.

“These events offer a snapshot of the many connections that shape food webs, and they provide insights into an important source of vertebrate mortality that appears to be less common outside the tropics,” said study first author Rudolf von May.

The study is published in the journal Amphibian & Reptile Conservation.