FYFD

Tag: biology

  • Closing a Venus Fly Trap

    Closing a Venus Fly Trap

    The Venus fly trap has long fascinated scientists with its ability to catch fast-moving prey. Just how the plant closes its “trap” leaf so quickly is a matter of debate. A new study gives us more detail–but not complete clarity–about what’s going on.

    One way that plants move rapidly is by moving water into or out of cells, changing their internal pressure. The new experiments showed that this is not what the fly trap does. Specifically, by watching the speed at which individual Venus fly trap cells take up water, the team concluded that closing the leaf would take 30-150 seconds–far more than the 1 second observed.

    Instead, the team showed that the trap’s rapid closure happens because the plant’s cell walls rapidly soften, making the leaf unable to stay open against previously-stored elastic energy. Instead, the trap snaps closed. The physical mechanism behind the softening is still unclear, though, so the charismatic plant still has mysteries for us to discover. (Image credit: N. Suzuki; research credit: J. Ryu et al.; via Nature and Gizmodo)

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  • Oyster Reefs Sequester Nitrogen

    Oyster Reefs Sequester Nitrogen

    The US eastern seaboard was once blanketed with oyster beds, but overharvesting, pollution, and habitat destruction decimated the population. As filter-feeders, oysters are naturally good at cleaning intertidal zones, and the reefs they build by cementing themselves to one another provide valuable habitat for many species of fish. A new study shows that oysters are even more economically valuable than we knew, thanks to their ability to sequester nitrogen.

    Agricultural and industrial run-off carries nitrates into the ocean in high concentrations that trigger deadly phytoplankton blooms, which choke off oxygen levels for larger species like fish. One way to reduce nitrogen levels in the water is denitrification, a process where microbes break down the nitrate into, among other things, inert nitrogen gas. The surface of oyster reefs is one place where this happens. But nitrates that evade these microbes can also get trapped and buried by a growing oyster reef.

    To understand how much nitrogen an oyster reef can bury, researchers studied cores removed from restored oyster beds. Below the top ten centimeters (where microbes do their denitrification), nitrogen levels in the oysters increased, with a square meter of oyster reef, on average, sequestering 6 grams of nitrogen per year, comparable to the amount that microbes removed. But some oyster reefs outperformed others. In particular, intertidal flat reefs–which grow faster–buried more than twice the nitrogen of subtidal reefs.

    The team estimated that, in North Carolina’s Carteret County, oyster reefs sequester some 120,000 kilograms of nitrogen annually, at an economic value of over $3 million. (Image credit: J. Andrews/UNC-Chapel Hill; research credit: A. Smiley et al.; via Eos)

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    Moths Taking Flight

    Insect flight is vastly different than the aerodynamics engineers learn around aircraft. That’s particularly apparent looking at these tiny moths taking off and flying in slow motion. Almost every feature seems, at first glance, aerodynamically wasteful. Hairy, scaly surfaces instead of smooth ones? Relatively small wings for their body size? Moths break our engineering intuition.

    For moths, flight is an inherently unsteady process. Every stroke of its wings cups and flings fluid away in an effort to generate enough lift to stay aloft. Notice how the wings flex with each stroke. Part of the moth’s efficiency comes from that flexibility, even though keeping wings relatively stiff is the norm for engineering larger fixed-wing craft. And those hairy surfaces? Not only can they help camouflage insects; they keep them hydrophobic so that water bounces off them. (Video and image credit: Ant Lab/A. Smith)

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    Drying Out Microbe-Filled Droplets

    Ocean sprays, coughs, and sneezes are just a few of the ways that droplets full of bacteria and salt can get aloft on a breeze. How do these bacteria stay viable even as their droplet evaporates? That’s the question behind this video’s research.

    When a bacteria-laden droplet or a salt-laden droplet dries, the evaporating droplet’s contact area shrinks, leaving behind only a concentrated lump of bacteria or salt. But when droplets contain both salt and bacteria, the drying droplet’s contact line gets pinned, leaving a larger area stain. The bacteria’s presence seems to promote crystallization of the salt, which–in turn–traps water in isolated spaces, perhaps helping the bacteria stay viable longer. (Video and image credit: R. Ran et al.)

    Animation of three droplets drying out. When all three components–water, salt, and bacteria–are in a droplet, the drying process looks very different.
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  • On Dolphin Turbulence

    On Dolphin Turbulence

    Dolphins are such fast and agile swimmers that, naturally, scientists have long wanted to understand how they swim so well. A recent study draws on numerical simulation to analyze the flow a dolphin creates when flapping its tail.

    The resulting flow is highly turbulent–researchers were only able to simulate up to a fraction of a dolphin’s actual Reynolds number–with both large-scale vortices and a cascade of smaller ones. The largest vortices, shown here in white, form on the upper and lower surface of the dolphin’s tail, then slide off the tail in a vortex ring. It’s these vortex rings, the researchers found, that provide the bulk of a dolphin’s thrust.

    The smaller-scale vortices, in contrast, get formed by the large vortices, and they make little to no contribution to the dolphin’s propulsion. Interestingly, these results suggest that we might be able to describe the propulsion of dolphins and other highly turbulent swimmers by focusing only on the largest scales in the flow. (Video, image, and research credit: Y. Motoori et al.; via Ars Technica)

    Animation of the simulated flow from a swimming dolphin.
    Animation of the simulated flow from a swimming dolphin.
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  • Herring Spawn

    Herring Spawn

    From mid-February to early May, tiny silvery Pacific herring gather along the shallow coastlines of Vancouver Island off British Columbia, Canada. In these sheltered waters, they spawn; female fish produce sticky eggs and males flood the area with milt, which turns the water a milky turquoise or green. The colors can be so vivid that the spawn is visible to satellites.

    Barkley Sound, on the island’s southwestern side, frequently hosts spawning, as its rocky shoreline provides protection and the pockets of lower salinity that the fish favor. After spawning, the fish migrate back to their feeding grounds in deeper, nutrient-rich waters. (Image credit: R. Cutler; via NASA Earth Observatory)

    A herring spawn clouding the waters along Vancouver Island on February 16, 2026.
    A herring spawn clouding the waters along Vancouver Island on February 16, 2026.
    A herring spawn event near Forbes Island in Barkley Sound turns the shoreline green.
    A herring spawn event near Forbes Island in Barkley Sound turns the shoreline green.
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  • Understanding Pollen Dispersal

    Understanding Pollen Dispersal

    When the wind blows, trees shift and sway, reconfiguring their shape and their leaves in response. For parts of the year, that flow can also pluck pollen grains off the tree, carrying them on the winds. A new computational simulation models this pollen dispersal from a tree, with the aim of eventually integrating into a tool for urban planners.

    Trees are an important component to fighting climate change, especially in cities, because they cool their surroundings in addition to providing fresh oxygen. But urban planners recognize the downsides to trees, too–allergies, anyone?–and, with the right tools, they could maximize the trees’ advantages while minimizing pollen spread for allergy-sufferers. (Image credit: M. Köles; research credit: T. Dbouk et al.; via Physics World)

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  • “Spiralling Textures”

    “Spiralling Textures”

    Wet fur forms a spiral of spiky hairs in this image by photographer Ben Dalgleish. For thin and flexible fibers like hair, a little moisture lets them clump together, forming stiffer (but still flexible) shapes. The technical term for this water-meets-flexible-solid phenomenon is elastocapillarity, and it lets you do things like wind a wire with a bubble. It also makes a big difference when washing hair, including in space. (Image credit: B. Dalgleish/BWPA; via Colossal)

    "Spiralling Textures" by Ben Dalgleish
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  • Inside an Ear

    Inside an Ear

    Our ears, like those of many other animals, convert mechanical signals to electrical ones, through a Rube-Goldberg-esque series of transformations. External sound waves make their way down the soft tube of the ear canal, which funnels them to a thin-walled cone, the eardrum, that’s about half as large as a dime. Here, the vibrating air pushes against the cone’s membrane, and those vibrations travel onward through a linked trio of small bones that amplify the vibration’s amplitude.

    The last of these bones presses against an even smaller, oval-shaped membrane. As the bone moves, it shakes the membrane, sending waves through the liquid on its other side. Those waves travel down the spirals of the tiny, pea-sized cochlea, named for a snail shell’s shape. As the waves move through the liquid, they bend bundles of hair-like strands back and forth, like tall grass waving in a breeze. The bending triggers a chemical that binds to nerves at the base of the bundles, sending an electrical signal through the nerve and into the brain.

    But the hair-like bundles, known as stereocilia, are also able to amplify incoming vibrations. In this case, the bundles in the outer portion of the cochlea expend energy to bend more than the incoming vibrations naturally make them move. This bending amplifies the fluid motion that gets transmitted to stereocilia further down the line; it’s those bundles that will make the final conversion to an electrical signal the brain receives. (Image credit: B. Kachar; research credit: Y. Thipmaungprom et al.; via APS)

    Scanning electron microscope view of the stereocilia "hair bundles" inside a frog's inner ear.
    Scanning electron microscope view of the stereocilia “hair bundles” inside a frog’s inner ear.
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    Understanding Fish and Turbines

    Fish detect turbulence in the water around them; among other things, this helps them avoid colliding with objects. Here, researchers are looking to understand how fish interact with underwater turbines. Experiments give them a set of trajectories that actual fish follow when dealing with the experimental turbine. But to understand what the fish is detecting, the researchers build a digital facsimile of the turbine and use Large Eddy Simulation (LES) to calculate the turbine’s wake.

    By overlaying the fish trajectories onto the simulated flow structures, they can better understand what flows the fish is and is not comfortable with. That knowledge helps engineers design turbines with smaller ecological impact. (Video and image credit: H. Seyedzadeh et al.)