A nighttime stroll can lead to something unusual. But a moment that can change scientists' understanding of an entire group of animals is something special.
As Smithsonian magazine reported, that's exactly what happened in a cloud forest in Ecuador, where a nature guide spotted a harvestman-like spider eating a live frog about its own size.
What's happened?
The publication noted that the sighting occurred in February 2020 during an evening walk through the 7,900-acre Mashpi-Tayra Preserve, home to the Mashpi Lodge. Lizardo Proaño was leading hikers through the forest when he spotted the spider feeding on a frog, and his colleague Juan Carlos Narváez photographed the scene, Smithsonian magazine reports.
As he told the publication, Proaño had seen harvestmen feed on worms, caterpillars, and once even part of a scorpion's tail, so the encounter with the frog didn't seem particularly remarkable to him.
«"I didn't know it was anything special," Proaño told Smithsonian magazine. "I thought it was normal because frogs are good prey for everyone.".
However, as the publication reported, when biologist Esteban Calvache later reviewed the images, he realized that this was a much more significant event than it first appeared.
In a study published in April in the journal Ecology and Evolution, Calvache, Proaño, Narváez, and their co-authors reported only 10 documented cases of harvestmen attacking adult frogs in the wild worldwide. All were recorded in South America.
In several cases, the frogs were still alive, suggesting that these long-legged arachnids may not simply be scavengers. They may also be active hunters.
Why is this important?
This observation complicates our understanding of tropical food webs. Arthropods are often viewed as prey for vertebrates, rather than vice versa. But these observations suggest the picture may be more complex, especially in tropical forests, where harvestmen can be larger and more robust.
Harvestmen also remain poorly studied. Although they are often mistaken for spiders, Smithsonian magazine notes that harvestmen are a distinct group of arachnids, with approximately 6,660 described species and known for eating almost anything they can get their hands on.
This encounter occurred on a route used for ecotourism, where human presence can reveal behavior patterns that would otherwise go unnoticed.
According to Smithsonian magazine, harvestmen are most active late at night, with peak activity around midnight and 3 a.m. Therefore, researchers believe this behavior may be more common than scientific data suggests.
What is being done?
Scientists are now calling for more thorough study of these little-studied arachnids, particularly in tropical forests. Future research could help explain how harvestmen capture and immobilize slippery adult frogs, as well as whether males and females differ in their hunting methods.
As reported by Smithsonian, one of the cases described in the new article occurred on the iNaturalist platform, where anyone can upload photos of wild animals. For animals as difficult to study as harvestmen, these images can serve as scientific evidence.
This is a wonderful example of how responsible use of citizen science can shed light on new animal species and deepen our understanding of existing ones.
Protected areas like the Mashpee-Tayra Reserve can also increase the likelihood of such discoveries because they provide scientists, guides, and visitors with ongoing access to biodiverse habitats that remain pristine enough to support complex interactions.
«"There are many hidden secrets in the fog," Calvache concluded in an interview with Smithsonian magazine.
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