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  • A Robotic Water Strider Glides Using Feather-like Feet

    A Robotic Water Strider Glides Using Feather-like Feet

    While many robotic water striders have been developed over the years, scientists continue to discover ingenious insect traits to mimic. Recently, researchers built a strider-bot that speeds across the water’s surface using foot-mounted fans.
    Image Credits: The bio-inspired Rhagobot robot, with one of its foot-fans visible at left
    Dongjin Kim

    While many robotic water striders have been developed over the years, scientists continue to discover ingenious insect traits to mimic. Recently, researchers built a strider-bot that speeds across the water’s surface using foot-mounted fans.

    At just 3 mm in length, water striders from the genus Rhagovelia are truly remarkable.

    Feathery Leg Fans

    Feathery extensions on their middle legs spread on contact with water, scooping it like frog webbing to propel the insect forward.

    When lifted, the wet fan strands close into a narrow, paintbrush-like point. This streamlined shape reduces drag as the leg swings forward, ready for the next stroke.

    Image Credits:A fan-packin’ Rhagovelia water strider – in this photo, the fan and claw are pointing downward and are reflected in the water’s surface, which acts like a mirror
    Victor Ortega-Jimenez/UC Berkeley

    These fans let the insects race across the water at around 120 body lengths per second. Even more impressively, by extending a single water-grabbing fan on one side, they can execute sharp 90-degree turns in just 50 milliseconds.

    For engineers designing aquatic robots, such agility would be invaluable. Researchers from UC Berkeley, Ajou University, and Georgia Tech studied Rhagovelia in detail.

    Microscopic Feather-Like Design Revealed

    Electron microscopy revealed each fan is a flat, flexible ribbon with tiny feather-like barbules. This structure enables the appendages to spread out underwater and function like miniature oars.

    Image Credits:At left is a photo of the fan and claw at the end of Rhagovelia’s two oaring legs – at right, a colorized scanning electron microscope image of the fan shows the flat, ribbon-like microstructure of the barbs and the smaller barbules (green) that comprise the fan
    Emma Perry/Univ. of Maine and Victor Ortega-Jimenez/UC Berkeley

    The researchers also found that surface tension alone supplies the elastic force needed for the strands to spread out. Unlike previous assumptions, muscles don’t open the fans—they only keep them tense during the stroke.

    Building on these insights, the team developed a robotic counterpart called Rhagobot.

    Rhagobot’s Feather-Inspired Fans

    The robot measures 8 × 10 × 1.5 cm and has 1-mg fans on its middle legs, modeled after Rhagovelia with the same ribbon-like structure, each 10 × 5 mm.

    Image Credits: The semi-aquatic robot Rhagobot (left) alongside a close-up of one its bio-inspired fans, which opens upon contact with water
    Ajou University, South Korea

    The entire robot, tethered to an external power supply, weighs only about one-fifth of a gram. It now moves at twice its body length per second and turns 90 degrees in under half a second, with future versions expected to be faster and useful for rescue or environmental monitoring.

    Mechanical Intelligence Borrowed from Nature

    “Our robotic fans self-adjust using water surface forces and flexible geometry, just like in nature,” says Prof. Koh, co-author with Georgia Tech’s Prof. Saad Bhamla. “It’s a form of mechanical intelligence perfected by evolution over millions of years. For small-scale robotics, such efficient and specialized mechanisms could be crucial for pushing beyond the limits of traditional miniaturized designs.”

    The research, led by UC Berkeley’s Asst. Prof. Ortega-Jiménez, was recently published in Science. A video demonstration of Rhagobot is available below.

    Read the original article on: New Atlas

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  • Flamingos Stir up Whirlpools with their Feet and Beaks to Catch Prey

    Flamingos Stir up Whirlpools with their Feet and Beaks to Catch Prey

    When we think of a flock of flamingos, we usually picture their long pink legs standing in shallow water and their heads down as they feed. While it may seem calm, there’s actually a flurry of activity underwater. With their webbed feet and uniquely angled beaks, flamingos create swirling mini-tornadoes to trap prey.
    Credit: Pixabay

    When we think of a flock of flamingos, we usually picture their long pink legs standing in shallow water and their heads down as they feed. While it may seem calm, there’s actually a flurry of activity underwater. With their webbed feet and uniquely angled beaks, flamingos create swirling mini-tornadoes to trap prey.

    A recent study in the Proceedings of the National Academy of Sciences reveals that flamingos are actually specialized predators, employing active hunting techniques—challenging the common belief that they are merely passive filter feeders.

    Flamingos Hunt, Not Just Filter

    “Flamingos are true predators—they actively seek out moving animals in the water,” explained Victor Ortega Jiménez, an assistant professor at the University of California, Berkeley. “Their challenge is figuring out how to gather and concentrate these creatures to feed. While it may appear they’re simply filtering passive particles, that’s not the case—they’re actively targeting prey.”

    To start the study, researchers trained Chilean flamingos (Phoenicopterus chilensis) to feed from a water-filled tank, capturing their foraging behavior with high-speed cameras. They then used this footage to develop 3D-printed physical models that replicated the flamingos’ movements.

    The search for food starts with a “stomp dance,” where flamingos repeatedly stomp their flexible, webbed feet in the water. As the foot goes down, it opens; as it lifts, it closes—agitating sediment and dislodging tiny organisms like brine shrimp and mayfly larvae. This motion also creates small, tornado-like spirals that rise in the water. Tests with 3D models confirmed that the birds’ floppy legs are essential for forming these efficient vortices.

    Next, the flamingo brings its head and beak into action. It positions its L-shaped beak in the water with the angled tip parallel to the ground. Then, it begins “chattering”—rapidly opening and closing its beak around 12 times per second. This motion generates another vortex, helping to trap prey more effectively.

    Flamingos Enhance Feeding with Rapid Head Movements, Amplifying Vortex Effect

    But that’s not all. While feeding with its head submerged, the flamingo rapidly and repeatedly pulls its head up from the bottom. This quick movement creates powerful tornado-like vortices that stir up and lift particulate sediments, enhancing the effect of the stomp dance.

    “Flamingos are highly specialized for filter feeding,” says Ortega Jiménez. “It’s not just their heads, but also their necks, legs, feet, and various behaviors all working together to efficiently capture small, fast-moving organisms.”

    In addition to revealing new insights into their feeding habits, the researchers believe the principles behind the flamingo’s tornado-like motions could inspire improved methods for extracting tiny particles, such as microplastics, from water.

    Read the original article on: New Atlas

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