Tardigrades average about half a millimeter in size, with rear legs used for grasping

About 1,500 species of tardigrades have been identified by their unique physiology

Freshwater-bound eutardigrades live on mosses and lichens and are distinguished by variations in the shape and number of claws at the end of their legs. Marine heterotardigrades, which live on algae and deep-sea sediments, have been observed to possess feathers, inflatable appendages, and flagpole-like tails.

Tardigrades can survive in a dehydrated state for decades

Despite being known as water bears, these microscopic creatures can shut down their metabolism when entering cryptobiosis, squeezing more than 95% of the water from their bodies. In this tun state, tardigrades can even survive the vacuum of space.

Tardigrades typically live between 3 and 30 months

While avoiding predators, including other tardigrades, nematodes, snails, mites and some fungi, these organisms feed on decaying plant matter and cellular fluid, which they access by puncturing cell walls with their stylets—spear-like structures within their mouths.

Extreme temperature resilience appears to be temporary for tardigrades

Although often considered indestructible, scientists observed these creatures could endure temperatures near 150°C for only a few minutes in their tun state. Outside this state, only half the samples in a Danish study survived 37.1 degrees Celsius (98 degrees Fahrenheit) for 24 hours, making tardigrades extremotolerant rather than extremophiles.

Watch tardigrade samples under an optical microscope

Tardigrade samples can be collected by gathering moss and submerging it in tap water for 24 hours. The moss should then be cut and drained with a mesh sieve, and the water should be collected. Samples are observable in the water between 10x and 40x magnifications.

The name ‘tardigrades’ comes from the Latin word for ‘slow walkers’

Before being renamed for their movements, German pastor Johann August Ephraim Goeze called them Kleiner Wasserbär—little water bears—in the first published observations of the creatures in 1773. He noted their voracious appetite made them seem like bears under a microscope.

Oxygen and nutrients are circulated in tardigrade bodies through physical movement

Rather than having a circulatory system, oxygen is directly absorbed through their skin and spreads through a fluid called hemolymph as tardigrades crawl. When molting to grow, they shed their outer skin and stylets—sharp mouth parts used to pierce prey—which are regrown in their salivary glands.

Ballistic experiments show that tardigrades are unlikely to be an alien species

Those fired from guns at speeds as high as 825 meters per second (1,845 mph) could be resuscitated after impact. Shock pressure from greater speeds tore apart the samples, suggesting they could not survive asteroid impacts if brought to Earth from outer space.

Ticks are extremely hard to kill

These arachnids can transmit more than a dozen diseases to humans, and they're very resilient: Some can survive extreme heat and cold, live for years without a blood meal, and even survive multiple days underwater.

The fragility of the alpine tundra

This article takes readers into Rocky Mountain National Park's Alpine Tundra, an area above the tree line where only specially adapted plants can survive. One such plant is the cushion plant, which avoids strong winds by growing close to the ground...

Mosquitoes stop flying at wind speeds equivalent to the swishing of a horse's tail

This low-threshold for wind—halting flight at 2 to 3 miles per hour—underscores that the bugs are actually not particularly strong flyers. But they don't need to be particularly robust fliers since their tiny, dark bodies and erratic movements can make them challenging to spot.

Learn about endoliths, the polyextremophiles that thrive inside rocks

These organisms include species that live in Antarctica, where they perform photosynthesis using light and water that makes it through pores in sandstone. Others residing in Earth's crust can survive temperatures reaching 60 degrees Celsius (140 degrees Fahrenheit) while generating energy through chemical reactions involving nutrients and gases trapped in rocks.

A look at how fish less than two inches long climb up 50-foot waterfalls

Shellears use tiny hooks on their front pectoral fins to grip rock like Velcro and take many pauses to recover energy between bursts of movement. Their pectoral girdle—an arch of bone—supports the muscle system needed for the roughly ten-hour climb.

T. rex didn't stomp, it walked on tiptoes like a bird

A new biomechanical study analyzing four T. rex specimens, including the famous "Sue" at Chicago's Field Museum, found the dinosaur used a "distal-first" foot strike, described as landing on its toes before its heel, similar to a modern ostrich. The technique improved stride efficiency and shock absorption, letting adults reach speeds up to 14 mph, while younger, lighter T. rexes could sprint closer to 25 mph.

Mammals gradually expanded in size and diversity after the dinosaur extinction

After an asteroid impact caused a mass extinction event 66 million years ago, small mammals were among the few surviving species. With fewer predators, mammals steadily grew larger as new habitats emerged.

Explore different living beings' sizes, from DNA to whales and the Pando clone

The Pando is actually a single organism in Utah, comprising more than 47,000 stems connected by a vast root system. It spans roughly 108 acres. Meanwhile, the average human stands at 5 feet and 7 inches. DNA, the genetic instructions for life, stands at a height of 3.5 nanometers.

Turtles' sense of direction comes from sensitivity to Earth's magnetic field and wave movement

Female sea turtles use this ability to migrate hundreds of kilometers across the ocean from their feeding grounds to the beaches where they were born to lay their eggs. Researchers have found that these turtles can reach these beaches despite ending up significantly off course as they detour away from predators or toward foraging territories.

Atmospheric rivers are the largest freshwater transport mechanism on Earth

Serving as highways that carry the water vapor equivalent of up to 15 times the average flow of water at the mouth of the Mississippi River, atmospheric rivers are approximately 400 to 600 kilometers (250 to 375 miles) wide and provide 30-50% of the annual precipitation of the US West Coast.

Into the Mariana Trench

Located in the western Pacific Ocean, the Mariana Trench is the deepest known point on Earth. Its lowest point, known as Challenger Deep, is farther down than the height of Mount Everest by more than a mile. This 13-minute video discusses how the trench was formed, and the extreme conditions at the sea floor.

What are the ten largest deserts?

Read this article to learn more about the ten biggest deserts in the world—including what their climates are like, where they can be found, and just how big they actually are. Did you know, for instance, that Antarctica is home to the world’s...

Stagnant lids found on Mercury, Mars, and the moon prevent tectonic activity

Unlike Earth’s lithosphere, which is composed of plates dragged by convection, the outer shells of observed terrestrial bodies in the solar system are not exposed to sufficient stress to be pulled apart. Earth is expected to develop a stagnant lid in about 1.45 billion years.

Lightning bolts are about as thick as a garden hose

The conductive filament ranges from about 2.5 to 5.0 centimeters (1 to 2 inches), though its extreme brightness makes it appear much thicker and visible from miles away. Scars on individuals who suffer a direct strike produce Lichtenberg figures with similar maximum thickness.

Identify household beetles with this database

Beetles are the largest order of insects in the world, with over 400,000 described species. They are found on every continent except Antarctica, and in every habitat imaginable, from the deepest oceans to the highest mountains. A small percentage...

Particles found in Martian air pose significant risks to human lungs

Ultrafine dust, just 3 micrometers wide, is small enough to bypass lung defenses and enter the bloodstream, where its highly reactive chemicals can cause thyroid disease. Silica in the dust can also cause silicosis, a chronic and incurable lung disease.

During glacier surging, these bodies of ice can move over half a football field a day

The movement of these glaciers, which repeatedly speed up and advance for months or years after stalling or moving backward for a time, results from melting ice that reduces friction between them and the ground, allowing them to slide more quickly. Scientists note that this effect is becoming more frequent due to climate change.

Explore the animals that populate the depths of the ocean, from fish and coral in the first few hundred feet, all the way down to the bottom of the Mariana Trench.

Planarian flatworms are small, aquatic worms with exceptional regenerative capabilities. When cut, the worms can regenerate multiple bodies in a matter of weeks.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

Track the location of the Voyager probes, currently between 13 and 15 billion miles away from Earth.

In 1963, a basement renovation in Turkey revealed a passageway to a hidden, multilevel underground city that once housed as many as 20,000 people

Tattoos remain visible on your skin thanks to immune cells called macrophages

Poison ivy will likely become both larger and more resilient due to climate change.

Astronauts have repaired genetic damage in space using CRISPR—a molecular tool that can make precise changes to DNA and is used in single-celled organisms to attack invasive viruses.

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

About 12.5% of US adults experience a phobia in their lifetime, a diagnosis that hinges on the intense fear interfering with daily life and persisting for at least six months.

The American cockroach is actually from Africa, an apparent hitchhiker aboard ships carrying enslaved people, with evidence suggesting the bug may have arrived in the New World as early as the 1600s.

Corals are themselves not coral reefs—the term refers to the tiny marine invertebrates that build the rigid reef.

Human-to-human transmission of hantavirus remains extremely rare, so the 2026 hantavirus cruise ship outbreak doesn't mean we're facing a COVID-style pandemic risk.

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

Objects can be 3D printed with light by projecting 2D computerized tomography (CT) scans onto rotating cylinders of resin, which solidify upon exposure.

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

See how Budweiser's famous Clydesdales spend their days at Warm Springs Ranch, where roughly 70 to 80 of the beer brand's giant horses can be found at any given time.

Take a 3D tour of the Hajj, Islam's annual pilgrimage to Mecca, undertaken by more than 1.5 million Muslims each year.

A pickleball's loud 'pop' sound can reach 120 decibels, which is equivalent to a hammer hitting a nail

About 2,000 US babies are born annually without some portion of their limbs, potentially leading to a lifetime of pricey prosthetics.

In 2019, a laptop loaded with six of the worst malware in history and described as 'an exhibit of historical weaponry' sold for $1.3M.