microorganism swimming dynamics

A ring-shaped channel of gallium arsenide is like a round pool with no rim: electrons flow in through the inner bank and out through the outer one. In an ultraclean material, they collide with each other more often than with lattice defects, and they begin to behave like a fluid.

Every fall, Issaquah Creek in Washington State turns into a maternity ward for thousands of salmon. The fish swim in, spawn, and die, and the water carries away their molecular traces: fragments of DNA, short-lived RNA, chemical marks on the genetic text. From September through November 2024, researchers collected a liter of water every week and ran it through a filter to catch those traces.

A courier carrying a package enters a dense forest of intertwined ropes. He needs to deliver the cargo deep inside, but along the way he loses strength, and each step becomes harder. This is what an enzyme looks like as it degrades a dense gel of biological molecules. Until recently, no one could simultaneously see how the courier moves and how the forest thins out.

A weaver sits at her loom, her hands moving in a rhythm that cannot be predicted in advance. The threads converge and diverge, forming a pattern that seems random yet follows strict rules.

A swimmer in a pool filled with light balls pushes off them and swims faster than in clear water. That is roughly how a trypanosome, a single-celled parasite that causes sleeping sickness, behaves when it enters blood, where red cells occupy nearly half the volume.

Every Martian night, salt crystals on the planet's surface soak up moisture from the thin air, much like a sponge draws water from a damp cloth. By morning, a microscopic brine accumulates inside them, and during the day, as temperatures rise, that brine finds itself trapped in tiny cavities.

In an aquarium the size of a dining table, two schools of black neon tetras swim in adjacent compartments separated by a transparent wall. They cannot touch each other, but they see every movement. And here's the surprising part: when one school decides to turn left, the other does the same a moment later. It's like two pendulums hanging behind glass, starting to swing in rhythm.

A crowd of pedestrians in a square moves chaotically: each person goes their own way, occasionally bumping into others. If every third person in that crowd wears a protective suit that blocks the pathogen, the rhythm of disease spread changes abruptly. That is exactly the scenario scientists reproduced by simulating 3000 self-propelled particles that repel each other and become infected upon close contact.

A lake in a drought doesn't dry up all at once. First, islands of dry land appear on the water's surface, they expand and merge, and only then does the water recede from the exposed bed. A mirabilite crystal behaves similarly when it loses water: round patches of anhydrous salt appear on its surface, growing outward and then beginning to deepen.

A raindrop slides on the wind and hits the ocean not straight down but at an angle. At that moment, its energy splits into two channels: one pushes the water forward along the flight path, the other presses it downward into the depths. Which channel proves stronger determines what happens at the surface: a quiet submergence, a fan of spray to one side, or a crown that shatters in all directions.

A slice of eucalyptus a tenth of a millimeter thick is placed under a polarized light microscope, and the wood suddenly blooms: blue, yellow, and pink bands twist into spirals, forming rings and swirls. This is not paint but the play of light: the cellulose fibers that make up cell walls transmit light differently depending on their orientation.

The orchestra starts playing, but each musician has their own tempo. If everyone plays at roughly the same speed, the music flows in a continuous stream. But if one group of instruments plays noticeably slower than the rest, the sound gathers into a dense clump that slowly moves forward.

The house where a cell lives has four rooms: mitochondria, the nucleus, the cytosol, and the plasma membrane. Until now we could only see that a fire had lit up somewhere, without knowing which room it was in. Now we have four windows, and each one shows its own part of the house.

Swimming season opens when the water feels tolerable. But everyone has their own threshold: one person shivers at twenty degrees, another swims comfortably at fifteen. Scientists decided to figure out where this difference comes from. They compared a swimmer's body to a house trying to keep heat in while a cold wind blows outside.

An oil droplet in water is like a ball in a crowd. When the crowd is sparse, the balls move apart freely. But if there are many people, each is squeezed by its neighbors, and the whole mass behaves like a single body. That's roughly how an emulsion works — a mixture where oil droplets float in water or vice versa.

Life begins with a bubble. In a warm puddle on ancient Earth, fat molecules could gather into tiny spheres — prototypes of cells. Inside such a sphere, a polymer happened to be present that accelerated the uptake of new fats from the surrounding water. The bubble grew, divided, and passed its composition to offspring.

A sphere rolls down a chute. What shape should the chute be to make the descent as quick as possible? Three centuries ago, the answer was the cycloid — a curve resembling the arc of an upside-down bridge. But submerge the chute in a thick liquid, and everything changes: the fluid slows the sphere, and the fastest path becomes something else.

In a thin glass chamber filled with water, life is boiling over: millions of tiny bacteria Thiovulum sp. ST, freshly isolated from a natural spring, start moving as a single organism. At first, they are evenly distributed, but within a few minutes the water begins to stir — large vortices appear, just like those in a pot of soup heating up on the stove.

A drop of saltwater dries on a table. The salt doesn't settle just anywhere: crystals first appear at the rim, forming a ring, like coffee grounds at the bottom of a cup. Everyone who has seen the stain left by a dried droplet knows this behavior. But what if the droplet contains swimming bacteria?

Epithelium lines our organs like tiles on a floor. At rest, cells cling to each other, and the tissue is elastic. But during embryonic development, wound healing, or tumor growth, this layer begins to flow like thick honey. What exactly triggers such softening?

A raindrop falls on glass and flattens into a pancake. Add a bit of polymer to the water, and it becomes elastic, like jelly. You'd think such a jelly would spread differently.

A cluster of glowing dots drifts through the darkness, now compressing into islands, now spreading out in waves. These are not fish or birds: this is a mathematical model of active matter, where each particle spends its own energy on movement, and also is born, dies, and competes with neighbors for space.

The universe right after the Big Bang was like a boiling cauldron: bubbles of a new state of matter were bursting and growing everywhere. These were first-order phase transitions — exactly like water boiling, only at temperatures reaching trillions of degrees.

A bacterium swims toward food. A chemical signal guides it forward, but with each movement the signal changes. A loop emerges: sensation, action, new sensation. The authors turned this loop into a measurable quantity.

A bacterial biofilm is like a city made of slime. The houses are the microbes themselves. The streets and bridges are long polymer molecules that bacteria secrete outside. This whole construction is not static: the bridges are constantly breaking and re-forming. The authors built a "toy" computer model of such a city.

A night river is dotted with tiny sparks. This isn't plankton: it's functional pollen-sensors, millimeter-sized devices that swim on their own and measure the water's chemistry. Each particle is a tiny lab. Inside, two reagents meet: one triggers a glow upon contact with a pollutant, and the second, a colored filter, blocks out interference.

Imagine a packed subway car at rush hour. Passengers don't just stand there: they breathe, release moisture, squeeze toward exits, and sometimes get stuck in doors, blocking movement. Now imagine these passengers can remodel the car's walls, add handrails, or turn the floor into gel.

In a world where Reynolds numbers are minuscule, water turns into thick syrup, and the swimming tricks we know stop working. Here reigns the insidious scallop theorem: reciprocal motions produce no net displacement. Microorganisms found a way out: they grow polymer tails.

In the intricate dance of active turbulence, where invisible engines spawn chaos, a soft droplet takes on the role of a detective. Its shape is not merely an outline but a sensitive cipher: it reads the hidden signals of its environment.

In the coastal shallows, where water retreats and returns, life follows the rhythm of the sun. The brownish film on the mud's surface is not just dirt but a dense community of tiny diatoms. By day they get plenty of light for photosynthesis, but when the sun gets too intense, a chemical storm brews inside the cells.

Quantum matter rarely treats us to the spectacle of self-motion. Where the classical world teems with starling murmurations, fish schools, and bustling bacteria, quantum thermodynamics long remained serene.

Membraneless organelles, tiny factories inside the cell, defy conventional rules. Take the nucleolus: here ribosomal RNA is synthesized — long chains woven from carbon sugars, rich in oxygen phosphate groups, and stitched with hydrogen bonds, suspended in the watery environment of the nucleus.

In the new model, each active particle has an internal rhythm: it spins either left or right. Chirality is key: some twirl clockwise, others counterclockwise. But when such a particle bumps into an obstacle or a neighbor, it flips its spin, like a figure skater who, after touching the board, explodes into a reverse pirouette.

A microplastic particle drifts on the surface of a warm sea. Within days, invisible hitchhikers, bacteria and single-celled algae, cover it. This living film acts as ballast: the particle becomes heavier and starts to sink. In a new global model, oceanographers have for the first time tracked the fate of such "hitchhiking" plastic across the entire planet.

A living sheet of cells resembles a crowd on an escalator. In a calm state, everyone moves smoothly, but as soon as a crush occurs, movement comes to a halt. Similarly, cell layers under load can suddenly stiffen, turning from a pliable mass into an elastic scaffold.

In the watery environment, vortices batter the mechanical fish. The AI agent, like an experimental chef, ran simulations, tried out 'recipes' of movements, and improved the program. Each experiment was like spectroscopy: the agent broke down behavior into elements, uncovering patterns. At first, the fish only paddled in one direction.

A supersolid is matter that is both crystalline and fluid. It is created from atoms cooled almost to absolute zero. In new work, physicists obtained such a substance as a triangular lattice of droplets. Each droplet oscillates in its own rhythm.

Imagine two immiscible liquids, such as oil and water. Under normal conditions, they tend to separate, forming a clear interface. But introduce microscopic swimmers (bacteria, whose basis is carbon) and the picture changes dramatically.

A drop of thick shampoo falls into water and freezes into a strange rope. A liquid that both flows and springs back is called viscoelastic. In it, tiny particles under ultrasound behave quite differently than in water. Viscoelasticity is a material's ability to both spread like honey and return to shape like rubber.

A cell crawls over a gel (sometimes viscous, sometimes elastic) and decides on its own when to speed up. It doesn't just glide: its internal chemical motor (noise in gene expression can affect the production of 'fuel') pushes the leading edge, while the rear detaches from the substrate.