Poison frogs exhibit a strange behavior that scientists are trying to explain

Faster then Gene Kelly Tap dancing in the rain, many species of poison dart frogs tap their middle toes on their hind legs so quickly that it looks like a blur.

Three laboratories in different countries recently set out independently to understand why. Their studies all suggest that the presence of prey affects these frogs' tapping, but the purpose of all that fancy footwork is still mysterious. The research could help explain similar behavior in other frogs and toads, as dozens of species make some sort of toe or foot flick while hunting.

The latest study, which was posted online last month but has not yet been published in a peer-reviewed journal, came from biologists at the University of Illinois Urbana-Champaign. The researchers observed colorfully painting poison dart frogs tapping up to 500 times per minute, or more than three times as fast as 'Shake It Off' by Taylor Swift.”

When the frogs saw fruit flies in a petri dish but couldn't reach them, they tapped less often. This suggests that the tapping could be related to their ability to catch their meal.

But the team also found that toe tapping was not related to the frogs' success in catching prey. This “confused us a little bit, and we're still thinking about that,” says Thomas Parrish, who worked on the study as an undergraduate with Eva Fischer, a biology professor.

Although some mysteries remained, it became clear that the amphibians' dance floor mattered. The team of Dr. Fischer found that frogs tapped their toes the most when they were on leaves in an aquarium, compared to when they were placed on agar gel, soil or glass.

Because leaves transmit vibrations easily, this result supports the idea that the frogs might tap to encourage the prey to move and to more easily detect the tasty insects. (These frogs only click their tongues at live, moving insects.)

Another hypothesis that many scientists have considered is that the tapping vibrations could lure prey closer, similar to how turtles stick out their tongues to imitate worms and how deep-sea fishermen attract food with their glowing rod-like protrusion. But while Gulf Coast Toads Prey have been seen to move toward themselves with toe vibrations, but this has not been demonstrated in poison dart frogs.

A separate team of biologists set out to investigate the vibrations caused by tapping the toes. They used an accelerometer to record the tapping of yellow-striped poison frogs in a specially built tank.

“Here we are very Caribbean, so we imagine the frogs drumming,” said Luis Alberto Rueda-Solano, author of the study from the University of Magdalena in Colombia. The study, last published November in the journal Evolutionary Ecology and led by Natalia Vergara-Herrera, found that in about 37 percent of recordings, the frogs accelerated their toe taps before flicking their tongues to attack prey. Frogs with longer middle toes showed this acceleration more often.

The Magdalena researchers ultimately want to investigate whether the frogs sense the movements of their prey and other organisms through vibrations, with the signal going from their hind legs to their inner ears.

“It's a potentially very interesting example of a predator using sensory cues to manipulate the behavior of prey — at least that possibility exists,” said Reginald Cocroft, a biologist at the University of Missouri who worked on the study.

Does the size of the frog's meal matter? In a separate study Published earlier in 2023, Lisa Schulte and Yannis Köning of Goethe University Frankfurt in Germany experimented with green-black poison frogs at the Frankfurt Zoo, showing that both crickets and smaller fruit flies made the amphibians tick.

But other frogs' calls didn't inspire toe tapping, suggesting the behavior isn't just a general expression of excitement, said Dr. Schulte.

Dr. Schulte noted complementary results from each group's studies, which indicate a link between toe tapping and feeding in poison dart frogs.

All three groups plan to follow up on their findings and advance science toward finding out if toe tapping helps these frogs catch their food, or if they're just doing it for fun .