Several species have fascinated observers with their ability to leap sideways and soar into the air from the surface of a pond as if the water were land. One such breed native to Virginia and North Carolina is the cricket frog. The way these frogs move through the water could provide insight into future tools for robotics, watercraft and more.
Jake Socha, the Samuel Herrick Professor of Mechanical Engineering, leads a research team examining the cricket frog’s unique ability to “jump,” one other name for jumping multiple times in a row. The team’s findings were published in a scientific journal, the primary writer of which is certified researcher Talia Weiss.
“Jumping” is not actually a well-defined word for this behavior – one naturalist used it to explain the “water-hopping” behavior of frogs in 1949, and it has since been used to explain this sort of locomotion throughout the literature below, Weiss said . “Part of this research is not only examining this behavior in cricket frogs, but also trying to give ‘jumping’ a more precise, scientific definition.”
How do they do it? In their research, members of Socha’s team found that conventional wisdom generally holds that a frog swims through water without drowning, although this will likely require highly specialized anatomy. What does this frog have that other frogs do not have?
“Our lab has studied many animals, and many of them display fascinating behaviors in moving around their environment,” Socha said. “The humble cricket frog lives nearby and yet continues to surprise us with its abilities, further motivating our curiosity to know the world of the living.
Fast video for fast frogs
Cricket frogs are one of the smallest frogs in North America, easily fitting on the thumb of a median adult’s hand. To observe the cricket frog in motion, team members used a high-speed video camera. They recorded the frog jumping on each land and water, observing the movement of its legs because it moved on each side.
The team found that the frogs actually drown with each jump. While “jumping” gives the image of frogs freely jumping through the water with only their feet going beneath the water’s surface, the recordings showed a unique picture. Socha, Weiss and their teammates noticed that each time the frog fell after a jump, its entire body submerged. This movement didn’t resemble a frog jumping and dancing freely on the water, but more like splashing and jumping. Their movements could quite be called “porpoising”, after the movement utilized by porpoises or dolphins: jumping into the air from under the water’s surface.
Start from the water
The reason why cricket frogs previously appeared to bounce on water when them with their eyes is principally because of their rapid movement.
To record this ultra-fast movement, the team used a 20-liter glass tank and dropped frogs into it. High-speed cameras recording speeds of as much as 500 frames per second were aimed toward the side of the glass tank to capture the motion above and below the water’s surface. As the frogs jumped, the team captured their escape.
The footage was then slowed all the way down to a small fraction of its original speed. While watching the footage, team members made a surprising remark: the frogs had indeed drowned.
“It’s fascinating how easy it is to be fooled by the rapid movements of animals,” Socha said. “In this case, we’re deceived by a frog that appears like a jumping stone, but the truth is it jumps and dives several times in a row. Frogs are great at jumping, but most of them don’t exhibit porpoise behavior, and we still don’t. I do not know why. Is there anything special concerning the frog’s leap, or is it simply a matter of small body size?
By observing them in slow motion, team members could observe the frog’s movement because it retracted and prolonged its limbs. They also noticed that the angle of its body relative to the waterline played a job, allowing it to take care of balance within the water. They divided each jump cycle into:
- Start from a submerged position
- Antenna or time within the air after the jump
- Re-entry, back into the water
- Regeneration, reset for the following jump
In just over one second, the frog would launch completely submerged, extending its legs in an underwater push to propel its body above the surface. Its hind legs remained prolonged while moving through the air, and its forelegs switched from pressing against the body to reaching forward. The outstretched front legs hit the water first upon re-entry, and the hind legs are still outstretched because the water sinks. As it descends, the hind legs retract and bend back into the jumping position. Another jump is made, repeating the movement.
It’s principally a belly flap.
The team observed that the frogs made as many as eight jumps in a row, each of which was accomplished in lower than a second.
Understanding skittering is a vital discovery in biology, nevertheless it also holds other keys. This discovery provides a brand new physical basis for the long run of bio-inspired robotics. It may be utilized in a water testing system that should be deployed quickly, or in an amphibious drone that takes water depth measurements. These futuristic devices can take cues from nature and use proven methods that frogs have been using for hundreds of years.
