FYFD

Tag: biology

  • Penguin Poo Seeds Antarctic Clouds

    Penguin Poo Seeds Antarctic Clouds

    Forming clouds requires more than just water vapor; every droplet in a cloud forms around a tiny aerosol particle that serves as a seed that vapor can condense onto. Without these aerosols, there are no clouds. In most regions of the world, aerosols are plentiful — produced by vegetation, dust, sea salt, and other sources. But in the Antarctic, aerosol sources are few. But a new study shows that penguins help create aerosols with their feces.

    Penguin feces is ammonia-rich, and that ammonia, when combined with sulfur compounds from marine phytoplankton, triggers chemistry that releases new aerosol particles. The researchers measured ammonia carried on the wind from nearby penguin colonies and found that the birds are a large ammonia source, producing 100 to 1000 times the region’s baseline ammonia levels. In combination with another ingredient in penguin guano, the researchers found the penguins boosted aerosol production 10,000-fold. That means penguins can actually influence their environment, helping to create clouds that keep Antarctica cooler. (Image credit: H. Neufeld; research credit: M. Boyer et al.; via Eos)

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  • Artificial Reoxygenation

    Artificial Reoxygenation

    Phytoplankton blooms have blossomed in coastal waters around the world, driven by phosphorus and nitrogen in agricultural run-off. These large algal blooms deplete oxygen in the water, creating dead zones where fish and other marine life cannot survive. Typically, oxygen makes its way into the ocean at the surface, where breaking waves trap air in bubbles that, when tiny enough, dissolve their oxygen into the water. But this process mainly helps surface-level waters, and without means to circulate oxygen-rich water down to the depths, the low-oxygen state persists.

    Artificial reoxygenation is a possible countermeasure. Either by bubbling oxygen directly into deeper waters or by pumping surface-level water downward, we could increase oxygen levels in the water column. So far, though, artificial reoxygenation’s success has been limited; tests in a few bays and estuaries show that it’s possible to reoxygenate the water, but the effects only last as long as the artificial mechanism remains active. Stop the pumps and bubblers and the water will revert to its low-oxygen state in just a day. Even so, the measures may be worthwhile on a temporary basis in some places while we adjust agricultural practices and try to mitigate warming. (Image credit: Copernicus Sentinel/ESA; via Eos)

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  • Flamingo Fluid Dynamics, Part 2: The Game’s a Foot

    Flamingo Fluid Dynamics, Part 2: The Game’s a Foot

    Yesterday we saw how hunting flamingos use their heads and beaks to draw out and trap various prey. Today we take another look at the same study, which shows that flamingos use their footwork, too. If you watch flamingos on a beach, in muddy waters, or in a shallow pool, you’ll see them shifting back and forth as they lift and lower their feet. In humans, we might attribute this to nervous energy, but it turns out it’s another flamingo hunting habit.

    A mechanical model of a flamingo's foot reveals how its stomping and shape change create a standing vortex.

    As a flamingo raises its foot, it draws its toes together; when it stomps down, its foot spreads outward. This morphing shape, researchers discovered, creates a standing vortex just ahead of its feet — right where it lowers its head to sample whatever hapless creatures it has caught in this swirling vortex. And the vortex, as shown below, is strong enough to trap even active swimmers, making the flamingo a hard hunter to escape. (Image credit: top – L. Yukai, others – V. Ortega-Jimenez et al.; research credit: V. Ortega-Jimenez et al.; submitted by Soh KY)

    Video showing how active swimmers can get caught in the flamingo's stomping vortex.
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  • Flamingo Fluid Dynamics, Part 1: A Head in the Game

    Flamingo Fluid Dynamics, Part 1: A Head in the Game

    Flamingos are unequivocally odd-looking birds with their long skinny legs, sinuous necks, and bent L-shaped beaks. They are filter-feeders, but a new study shows that they are far from passive wanderers looking for easy prey in shallow waters. Instead, flamingos are active hunters, using fluid dynamics to draw out and trap the quick-moving invertebrates they feed on. In today’s post, I’ll focus on how flamingos use their heads and beaks; next time, we’ll take a look at what they do with their feet.

    As a flamingo retracts its beak from the bottom of a water tank, a tornado-like vortex forms.

    Feeding flamingos often bob their heads out of the water. This, it turns out, is not indecision, but a strategy. Lifting its flat upper forebeak from near the bottom of a pool creates suction. That suction creates a tornado-like vortex that helps draw food particles and prey from the muddy sediment.

    As a flamingo "chatters" its mandibles, it creates suction that can pull up food.

    When feeding, flamingos will also open and close their mandibles about 12 times a second in a behavior known as chattering. This movement, as seen in the video above, creates a flow that draws particles — and even active swimmers! — toward its beak at about seven centimeters a second.

    Video showing von Karman vortices trailing from a flamingo's head when placed on the water's surface. A recirculation zone forms at the tip of its beak, enhancing capture of food.

    Staying near the surface won’t keep prey safe from flamingos, either. In slow-flowing water, the birds will set the upper surface of their forebeak on the water, tip pointed downstream. This seems counterintuitive, until you see flow visualization around the bird’s head, as above. Von Karman vortices stream off the flamingo’s head, which creates a slow-moving recirculation zone right by the tip of the bird’s beak. Brine shrimp eggs get caught in these zones, delivering themselves right to the flamingo’s mouth.

    Clearly, the flamingo is a pretty sophisticated hunter! It’s actively drawing out and trapping prey with clever fluid dynamics. Tomorrow we’ll take a look at some of its other tricks. (Image credit: top – G. Cessati, others – V. Ortega-Jimenez et al.; research credit: V. Ortega-Jimenez et al.; submitted by Soh KY)

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    How Insects Fly in the Rain

    Getting caught in the rain is annoying for us but has the potential to be deadly for smaller creatures like insects. So how do they survive a deluge? First, they don’t resist a raindrop, and second, they have the kinds of surfaces water likes to roll or bounce off. The key to this second ability is micro- and nanoscale roughness. Surfaces like butterfly wings, water strider feet, and leaf surfaces contain lots of tiny gaps where air gets caught. Water’s cohesion — its attraction to itself — is large enough that water drops won’t squeeze into these tiny spaces. Instead, like the ball it resembles, a water drop slides or bounces away. (Video and image credit: Be Smart)

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  • Whale Migration Carries Nutrients

    Whale Migration Carries Nutrients

    When it comes to the movement of nutrients in the ocean, we think of run-off from rivers, upwelling along coasts, and convective currents. We don’t typically think about animal migrations, but a new study of baleen whales (including species like humpbacks and right whales) suggests that these massive mammals provide a small but critical spreading service.

    These whales feed in cold, nutrient-rich waters, like those in the Arctic, then travel thousands of kilometers to warm but nutrient-poor tropical waters to birth and raise calves. During that time, mothers do not hunt or eat; they live off their fat stores, which they also use to make milk for their offspring. Although they’re not eating during this time, they do still urinate, and it’s this activity that, according to researchers, adds some 3,000 tons of critical nitrogen to these areas. Since nitrogen is often a limited resource in these tropical waters, the whales’ urine may act like a fertilizer shipment for other species in their breeding grounds. (Image credit: C. Le Duc; research credit: J. Roman et al.; via Eos)

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    Tracking Insects in Flight

    Insects are masters of a challenging flight regime; their agility, stability, and control far outstrip anything we’ve built at their size. But to even understand how they accomplish this, researchers must manage to capture those maneuvers in the first place. Insects don’t stay in one small area, which is what the typical fixed camera motion capture set-up requires. Instead, one group of researchers has designed a system with a moveable mirror that tracks an insect’s motion in real-time, ensuring that the camera stays fixed on the insect even as it traverses a room or — for the drone-mounted version — a field.

    Real-time motion tracking means that researchers can better capture detailed footage of the insect’s maneuvers in a lab environment, or they can head into the field to follow insects in the wild. Imagine tracking individual pollinators through a full day of gathering or watching how a bumblebee responds to getting hit by a raindrop mid-flight. (Video and image credit: Science; research credit: T. Vo-Doan et al.)

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  • “Spines”

    “Spines”

    Water droplets cling to spine-covered plant life in this series from photographer Tom Leighton. The hairs are hydrophobic — notice how spherical the drops appear. Many plants make parts of their leaves and stems hydrophobic in order to redirect water toward their roots, where it can be taken in. Others use hair-like awns to collect and draw in dew that supplements their water capture. (Image credit: T. Leighton; via Colossal)

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  • Filtering Like a Manta Ray

    Filtering Like a Manta Ray

    As manta rays swim, they’re constantly doing two important — but not necessarily compatible — things: getting oxygen to breathe and collecting plankton to eat. That requires some expert filtering to send food particles toward their stomach and oxygen-rich water to their gills. Manta rays do this with a built-in filter that resembles an industrial crossflow filter. Researchers built a filter inspired by a manta ray’s geometry, and found that it has three different flow states, based on the flow speed. At low speeds, flow moves freely down the filter’s channels; in a manta, this would carry both water and particles toward the gills. At medium speeds, vortices start to form at the entrance to the filter channels. This sends large particles downstream (toward a manta’s digestive system) while water passes down the channels. At even greater speeds, each channel entrance develops a vortex. That allows water to pass down the filter channels but keeps particles out. (Image credit: manta – N. Weldingh, filter – X. Mao et al.; research credit: X. Mao et al.; via Ars Technica)

    An animation showing three different flow states through a manta-ray-inspired filter.
    Depending on the flow speed, a manta-inspired filter can allow both water and particles in or filter particles out of the water.
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  • Flying Without a Rudder

    Flying Without a Rudder

    Aircraft typically use a vertical tail to keep the craft from rolling or yawing. Birds, on the other hand, maneuver their wings and tail feathers to counter unwanted motions. Researchers found that the list of necessary adjustments is quite small: just 4 for the tail and 2 for the wings. Implementing those 6 controllable degrees of freedom on their bird-inspired PigeonBot II allowed the biorobot to fly steadily, even in turbulent conditions, without a rudder. Adapting such flight control to the less flexible surfaces of a typical aircraft will take time and creativity, but the savings in mass and drag could be worth it. (Image credit: E. Chang/Lentink Lab; research credit: E. Chang et al.; via Physics Today)

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