Unexpected Predators: Daddy Longlegs Eating Frogs

They resemble, in a way, daddy’s frog legs.

Typically known for their diet of insects and other small invertebrates, daddy longlegs are now being observed as they take on larger prey. Researchers in South America have spotted these curious arachnids feeding on small frogs that are, surprisingly, bigger than themselves. The findings were documented in a study published in the journal Ecology and Evolution.

“It was completely unexpected to see these creatures eating frogs. We hadn’t imagined they could catch them,” shared biologist and co-author Luis Fernando García from the University of the Republic in Uruguay.

The research is based on ten reports of this unusual feeding behavior, which seems to flip the usual predator-prey dynamic between insects and amphibians on its head.

This included field observations throughout South America, academic papers, and contributions via iNaturalist, a platform where anyone can share wildlife photos.

Co-author Lizardo Proaño remarked that when he witnessed harvesters consuming these frogs, he didn’t initially think much of it. “I assumed it was normal since frogs are pretty easy pickings. They lack scales or hard bones. They’re like gummy bears in the forest,” he reflected.

It wasn’t until later that he realized how rare this behavior was in scientific literature. There had been no prior observations, and it was uncertain whether these long-legged critters were scavenging dead frogs or actively hunting for them.

Interestingly, the researchers leaned more towards the idea of active hunting, as the frogs were often found alive during these encounters.

In fact, some frogs were found to be up to 1.29 times larger than the ones caught. This is quite impressive considering these arachnids are non-venomous and rely on their physical capabilities for success.

The study suggests that these creatures might utilize their spiny mouthparts or forelimbs, known as palps, to grip their slippery prey, similar to the strategy used by a predatory praying mantis.

“They depend entirely on their ability to physically restrain their capture,” speculated ecologist José Valdes from Germany’s Martin Luther University Halle-Wittenberg, who wasn’t involved in the study.

The researchers also hypothesized that these harvesters might be focusing on frogs that were injured, sluggish, or perhaps even drowsy.

Why would these long-limbed arachnids start hunting amphibians? Well, simply put, researchers suggest it’s because they can.

“If you can catch one, why not eat it?” questioned study author Esteban Karbaş, a biologist at Mashpi Lodge who has observed this formidable feeding behavior.

He humorously noted the regional context, indicating that the harvesters can be quite opportunistic, taking advantage of the abundance of amphibians.

Additionally, tropical harvesters tend to be larger than their temperate relatives, so it makes sense they might target more substantial prey like frogs to sustain their size.

More research is certainly needed to delve deeper into this unique predatory behavior.

Interestingly, harvesters aren’t the only arthropods known to prey on vertebrates. The Goliath bird-eating spider, recognized as the largest arachnid in the world, has also been reported to munch on everything from mice to birds, which is quite a feat in itself.

This massive tarantula is sometimes consumed by indigenous people in South America, with some gourmet enthusiasts likening its taste to crab or smoked shrimp.