FYFD

Tag: biology

  • Surfing Honeybees

    Surfing Honeybees

    Honeybees have superpowers when it comes to their aerodynamics and impressive pollen-carrying, but their talents don’t end in the air. A new study confirms that honeybees can surf. Wet bees cannot fly–their wings are too heavy for them to get aloft when wet–but falling into a pond isn’t the end for a foraging honeybee.

    Instead, the bee flaps its wings, using them like hydrofoils to lift and push the water. This action generates enough thrust to propel the bee three body lengths per second. It’s a workout the bee can only maintain for a few minutes at a time, but researchers estimate honeybees could cover 5-10 meters in that time. Once ashore, the bee spends a few minutes drying itself, and then flies away no worse for the wear. (Image and research credit: C. Roh and M. Gharib; via NYTimes; submitted by Kam-Yung Soh)

  • Seeing Past the Surface

    Seeing Past the Surface

    Satellite imagery has revolutionized remote sensing and our ability to observe the world around us. But peering past the surface of water has always been next to impossible. We might be able to see the extent of a coral reef from a photo, but thanks to the interplay of light and water, the details are too blurry to identify what species we’re looking at.

    To solve this issue, researchers decided to work backwards, taking everything we understand about the physics of light – refraction, reflections, and so on – and using it to remove the distortions. The result is NASA’s FluidCam, an instrument capable of of taking a video of shallow waters less than 10 m deep, processing it, and producing images with sub-centimeter accuracy showing what lies beneath. Tests in American Samoa revealed details fine enough that scientists were able to identify multiple coral species as well as many of the species of fish inhabiting the reef. 

    With coral reefs changing quickly, this technology may be invaluable for monitoring coral health without actively disrupting these delicate systems. (Image credit: N. Usry; research credit: V. Chirayath and A. Li; via OceanBites; submitted by Kam-Yung Soh) 

  • Whale Feeding

    Whale Feeding

    Whether in groups or as individuals, humpback whales are canny hunters. They herd prey together by encircling them and releasing bubbles that form a “net” that bars escape. Then, the whales lunge through the center with open mouths, gathering prey. Scientists have long wondered whether humpbacks’ unusually long pectoral fins played any role in their hunting. New drone observations of whales feeding (see video below) are beginning to provide some hints.

    The scientific teams observed multiple individual whales feeding under the same circumstances and found that the whales used their fins quite differently. Both used them as additional barriers to prevent prey from escaping, but one whale favored a horizontal fin position that created currents that helped sweep prey into its mouth. The other whale used a more vertical fin position that, while hydrodynamically unfavorable, exposed its bright underside, which seemed to startle prey into fleeing into its darker, more inviting mouth. (Image credit: K. Kosma; video credit: M. Kosma; research credit: M. Kosma et al.; via Science)

  • Sliding Down a Pitcher Plant

    Sliding Down a Pitcher Plant

    Carnivorous pitcher plants supplement their nutrient-poor environments by capturing and consuming insects. The viscoelastic fluid inside them helps trap prey, but fluid dynamics plays a role elsewhere on the plant as well. The inner and outer surfaces of the pitcher are covered in macroscopic and microscopic grooves, seen above, oriented toward the interior of the plant. 

    Researchers found that these grooves trap droplets on the slippery plant through capillary action. Once adhered, the droplet cannot easily move across the grooves, but it can slip along them, carrying the droplet and any insect stuck to it, into the plant. By replicating pitcher-plant-inspired grooves on manmade surfaces, researchers found they were able to better control droplet motion on slippery, lubricant-infused surfaces than in previous work. (Image and research credit: F. Box et al.; via Royal Society; submitted by Kam-Yung Soh)

  • Escaping the Limits of Viscosity

    Escaping the Limits of Viscosity

    For large creatures, it’s not hard to feel the evidence of someone else swimming nearby. But to tiny swimmers water is incredibly viscous and hard to move. These creatures have to swim very differently than their larger cousins, and evidence of their motion dies out quickly. But at least one microorganism,  Spirostomum ambiguum, has discovered a method for overcoming the limits of size and viscosity.

    The single-celled swimmer, when threatened, contracts its body in milliseconds, generating accelerations greater than those seen by fighter pilots. That acceleration is strong enough that it generates a burst of turbulence powerful enough to overcome the natural damping of its viscous surroundings. Within their colonies, S. ambiguum seem to use contraction to send out hydrodynamic signals to neighbors, who pass on the call to arms. To see the colonies in action, check out this previous article. (Image and research credit: A. Mathijssen et al.; via Physics Today; submitted by Kam-Yung Soh)

  • If You Teach a Goose to Fly

    If You Teach a Goose to Fly

    Scientists do all manner of odd things in the name of science. To teach bar-headed geese – birds capable of flying at the altitude of Everest – to fly in a wind tunnel, one group of researchers fostered a group of geese from the moment they hatched. They taught them to fly, first by chasing their bicycling parent and then following her on a motor scooter. Only then could they train the geese to fly in a wind tunnel designed to test how these birds manage to keep flying with only 30% of the oxygen found at sea level*.

    The birds’ secret, it turns out, is metabolic. As the oxygen dropped, so did the temperature of the geese’s blood. Hemoglobin, which binds oxygen in blood cells, is more efficient at lower temperatures, allowing the birds to get more oxygen. At the same time, though, their overall metabolism slowed down, meaning that they required less oxygen overall to function. Taken together, these adaptations make the geese excellent fliers in conditions most animals cannot tolerate. (Image and research credit: J. Meir et al.; via WashPo; submitted by Marc A.)

    * Occasionally I get comments pointing out that drag decreases with altitude, thereby making it easier to cut through the air. While this is true, I can say from my own experience of living and exercising at altitude that, for most of us, the effects of low oxygen levels far outweigh the savings in drag. It’s hard to appreciate a tiny drop in drag when your heart rate is sky high!

  • The Impressive Take-Off of Pigeons

    The Impressive Take-Off of Pigeons

    One reason that peregrine falcons are such amazing fliers is that their prey, pigeons, are no slouches in flight, either. Able to take off vertically and accelerate to 100 kph in two seconds, pigeons are pint-sized powerhouses. With this high-speed video, BBC Earth highlights the mechanics of this vertical take-off. Pigeons begin by bending their legs and jumping high enough that their first downstroke can extend fully and still clear the ground. That gives them a headstart on generating the force they need to propel themselves upward. 

    Note the way the pigeon’s wings move, sweeping from directly behind the bird’s back to a full extension in front of it. With the bird moving vertically, this motion tells us that it’s thrust – not aerodynamic lift – from the wingstroke that’s powering this take-off. In that sense, the pigeon is something like a Harrier jet, using the thrust of air downward to take off vertically. (Image and video credit: BBC Earth)

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    Feathered Fighter Jets

    Peregrine falcons are built for speed. They’ve been clocked at more than 380 kilometers per hour when diving. This video from Deep Look examines some of the features that make these birds of prey so fast, from the shape of their eyes to the tubercles in their nostrils that help them breathe during high-pressure dives. 

    Part of the falcon’s speed comes from its signature stoop, where it pulls in its wings to form a tight, streamlined shape. This reduces drag forces on the falcon, letting gravity pull it toward a high terminal velocity. But even with its wings extended, the falcon exudes speed and agility. Its wings form a sharp leading edge to cut through the air, with stiff, overlapping feathers that slice the flow. Compare this to the feathers of an owl, which specializes in silence rather than speed for catching its prey. (Video and image credit: Deep Look)

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    How Ant Stingers Work

    Anyone who’s felt the sting of a fire ant knows it only takes an instant for this species to deliver a painful blow. Scientists are uncovering why that is using some of the first-ever high-speed footage of ant stingers in action. Stingers are actually made up of multiple separate pieces, including a central stylet and a pair of lancets that move up and down along the stylet. This lancet motion pulls the stinger deeper and helps form and deliver droplets of venom. The back-and-forth motion helps ants release up to 13 venom droplets per second, a level of speed that’s key for some of its high-speed, small-scale battles. (Image and video credit: Ant Lab; research credit: A. Smith)

  • Testing Vesicles

    Testing Vesicles

    In biology, vesicles contain a liquid surrounded by a lipid membrane. The characteristics of that membrane – like its stiffness – can change over time in ways that indicate other changes. For example, vesicles carrying HIV become stiffer as they grow more infectious. In the past, to observe these properties scientists used atomic force microscopes, which require removing the vesicles from the liquid in which they naturally reside. That’s problematic because it potentially changes how the vesicle responds. 

    Now researchers have developed a new method: a microfluidic system that subjects vesicles to electric fields in order to deform them and measures their properties without removing them from their carrier fluid. This provides a faster and more reliable method of testing a vesicle’s deformation, capable of testing hundreds of samples at a time. (Image credit: Wikimedia; research credit: A. Morshed et al.; submitted by Eric S.)