Gastroliths, or ‘stomach stones,’ help animals digest plants in their stomachs

Animals' stomach lining produces cheese

Cheesemaking would be impossible without rennet, the enzyme that separates milk’s liquid and solid components. Rennet occurs naturally in the stomach lining of young goats, cows, and lambs to help them digest milk, a process that also allows cheesemakers to use it to make curds. Now we have plant-based rennet that comes from thistles, artichokes, and other similar plants.

How snake biology allows them to eat prey larger than they are

Possessing flexible skulls with elastic ligaments and unfused jaw bones, snakes can open their mouths to engulf much larger prey, and adjustable airways enable them to continue breathing while their teeth grip onto their food. Through slow digestion and specialized cells that decompose bones, some snakes can survive on a single large meal for over a year.

Gladiators followed a mostly vegetarian, high-calcium diet

Analysis of skeletons from a gladiator cemetery at Ephesus by researchers at the Medical University of Vienna found little meat consumption but unusually high calcium levels—likely from drinking wood ash mixed with water to promote weight gain and protect vital organs.

Food passes through the digestive system via muscle movement known as peristalsis, a rippling contraction that pushes food onward through tubular organs.

Without liver bile, human poop would be a pale silver color

Stomach acid and enzymes break down food into smaller particles, expelling a semi-fluid mass called chyme into the small intestine, where bile is added. As the intestines absorb nutrients and water, the chyme solidifies and changes color.

Feeding grazing cattle seaweed cut their methane emissions by almost 40%

The largest share of the 12% of global greenhouse gas emissions from livestock comes from methane released when cows burp. A study found that introducing a seaweed supplement in pellet form significantly reduced these emissions without affecting cattle's health or weight.

The tongue evolved in animals roughly 350 million years ago

Creatures like fish rely on suction to consume food, flexing their gills to create water currents that vacuum up their meals. The evolution of the tongue enabled vertebrates to completely cut ties with the sea, moving onto land where they could sample new foods and ways to eat them.

Some animals, including certain tropical ants, have little or no microbial populations in their gut, upending the idea that all animals rely on this ecosystem to help maintain their health and proper functioning.

Stony corals form a type of calcium carbonate called aragonite from ions brought to the ocean by rivers that have broken down terrestrial rocks.

Coral reefs are built by thousands of coral polyps—tiny animals whose mouths both consume food and expel waste.

Prosthetics and orthotics have been 3D printed to improve the lives of animals

Shells for hermit crabs, wheelchairs for guinea pigs and dogs, and horseshoes for improved running performance have been created using 3D printers. Other artificial body parts made using this technology include a jaw for a loggerhead turtle, a beak for a toucan, and a tail for an American alligator.

The halting of human bone growth helps manage heat produced from metabolism

While fish, amphibians and reptiles get bigger throughout their lives until they die, their slower metabolisms allow their bodies to regulate the resulting smaller temperature increases. In humans, hormones triggered during puberty harden growth plates, ending bone lengthening.

Snake venoms are repurposed proteins responsible for other bodily functions

Just as saliva aids digestion in humans, proteins responsible for bioactivities such as digestion and blood clotting were eventually secreted in the glands and fangs of snakes across evolutionary history. Organisms that could not withstand the effects of these molecules (e.g., excessive bloodstream clotting) became ideal prey for snakes.

Diatomite, a sedimentary rock used as a filtration material in beer, wine, swimming pool water, motor oil, and pharmaceuticals, is formed from the fossilized shells of diatoms, a type of algae.

Scientists now know why wombats poop cubes

For years, scientists have been wondering why wombat poop is cube-shaped (yes, really). Now, they say they have got to the bottom of the mystery.

Ritual Maya dental ornaments may have prevented tooth decay

Analysis of Maya dental sealants shows they used plant resins and gums—some derived from pine with antibacterial properties—suggesting gemstone tooth inlays may have helped reduce infection while serving ritual and symbolic purposes.

What ancient goat teeth reveal about ancient human-animal relationships

About 4,000 years ago, several goats with terrible teeth managed to outlive their better-teethed brethren. With such intense dental damage, the goats were likely fed higher-quality feed than the more dentally gifted herd members, a dietary shift that would've contributed to the difference in life span. These goat teeth underscore the hard truth that humans may inflict harm on the animals they care about most, regardless of intention.

How humans digest food

Every day, the average human eats close to six pounds of food—all of which must be processed by the digestive system. Ten organs collaborate to transform food that the mouth chews into the energy needed to stay alive. (Stretched out, these organs...

How slugs helped soldiers during WWI

Slimy, squishy, slow-moving, and heroic? Slugs are land-dwelling mollusks known mostly for causing havoc in our gardens. But during World War I, slugs saved numerous soldier's lives as poison gas detectors. Learn how the unpleasant creatures earned their stripes in the battle to protect soldiers from chlorine, phosgene, and mustard gas as organic detectors.

Air sacs and lightweight bones helped some dinosaurs grow to enormous sizes

After the Triassic extinctions, new species with birdlike anatomy evolved from smaller, early dinosaurs. This anatomy allowed for more efficient breathing and lighter skeletons, favoring the evolution of larger organisms.

Fossilized bite marks suggest some dinosaurs may have engaged in cannibalism

An excavation site near the Colorado-Utah border contained Allosaurus bones with tooth marks of other Allosaurus, which may have occurred in response to a dry season in the area. The Tyrannosaurus and Majungasaurus have also been shown to eat their own.

What did it take to eat like a gladiator?

If you think gladiators were all rippling muscle, think again. Evidence suggests fighters weren't as cut as we've been led to believe. This article dives into the diets of ancient Roman gladiators, who may have eaten mostly vegetarian. Archaeological evidence gathered from the skeletons of 68 gladiators found in a 2,000-year-old Turkish grave suggests the fighters' diets mainly relied on barley and legumes, with little animal protein.

Variations in beak shape helped birds survive the dinosaur extinction event

The asteroid that struck Earth 66 million years ago killed some avian dinosaurs. The smaller species endured by reproducing more quickly and adapting to the environment. Their different beaks allowed them to eat more varied foods for survival.

GLP-1 drugs, first used to manage diabetes, were derived from Gila monster saliva.

After swallowing 23 pieces of plastic, seabirds experience a 90% death rate

Researchers found that this threshold is also met when marine mammals ingest 29 pieces and when sea turtles consume approximately 405 pieces. Almost half of the sea turtles, a third of the seabirds, and one in ten of the marine mammals studied had eaten plastic.

At Disney World, glass bottles and jars are pulverized into the smooth gravel and sand used in greenhouses that grow the flowers for the parks and resorts.

Rocks, crystals, and gemstones are all made of minerals—solids that form from natural processes, such as evaporated water leaving salt behind or lava rapidly cooling into a solid.

As environmental engineers—a main type of keystone species—prairie dogs support over 150 other species through their grazing habits and burrowing of underground tunnels, which serve as habitats for owls, snakes, ferrets, insects, and other organisms.

Unlike the roars in movies, dinosaurs likely cooed, rumbled, and boomed

Fossil evidence and CT scans suggest that many dinosaurs produced low-frequency sounds using resonating crests, closed-mouth vocalizations, or organs similar to those of birds and crocodiles. Larger sounds would not have been helpful for sneakily hunting prey.

Cold-blooded reptiles seek heat, and that behavior may help combat fungal infections

This Radiolab podcast episode takes on the idea that though our human bodies are too warm for the majority of fungal species to effectively replicate inside our bodies, that's not the case for reptiles. Yet when those species warm their bodies by basking in the sun on rocks, they can soak up heat and may also help keep fungal infections in check.

Birds are living dinosaurs that evolved from feathered theropods

Traits associated with birds, including feathers, laying eggs, and hollow bones, were first present in dinosaurs and carried through to their descendants. Fossils of these dinosaurs have been found in a sleeping posture, resembling roosting behavior.

Poison frogs get their toxins from eating insects and mice

Other animals, including royal ground snakes, are able to survive eating poison. Scientists study the creative antitoxin defenses in these animals to discover treatments for poisoning.

Eating competitions can ruin a stomach's elasticity

Competitive eaters make room for all that food by toying with the stomach's ability to expand and contract. Still, doctors warn that repeated stress can destroy that ability, leading to further issues.

From the Greek words meaning 'rock blanket,' regolith is any layer of material covering solid rock, including soil, rock fragments, and dust.

Most plastics are not biodegradable because breaking their chemical bonds requires temperatures lethal to most microbes, and these organisms have not been exposed to plastic long enough to evolve the necessary enzymes.

Alpha-gal allergy is a problem for red meat lovers, and that same alpha-gal sugar is an issue for xenotransplants, too—since it's present in pigs, human bodies reject pig-to-human transplants as foreign once they detect the substance.

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.

Dinosaurs suffered from cancer, arthritis, and infections seen in modern animals

Using CT scans and advanced pathology techniques, paleopathologists have identified respiratory illnesses, malignant osteosarcoma, and other diseases in dinosaurs. The research has helped show how many of these ailments are not exclusively modern phenomena.

As immobile animals, corals and the organisms that live on them have evolved a suite of chemical compounds to prevent disease and ward off predators they cannot outrun.

Pets of ancient Greece: crickets and ferrets and hedgehogs, oh my!

Ancient Greece left behind literature and art in which geese, doves, dogs, and the like are seen keeping people company or holding vigil for their return. Were these considered pets as we understand the term today, and where did ancient Greeks fall on the timeless question of cats versus dogs? Did Odysseus let Argos onto the sofa? This magazine article explores evidence of pets and their treatment in ancient Greece.

Plants use physical and chemical defenses to protect themselves

Tree bark is difficult to chew and resistant to pathogens, while the waxy cuticle on the surface of leaves deters insects and microbes. Some plants possess thorns, spines, and prickles to discourage predators. Plant cells can also produce antimicrobial toxins or release compounds to alert parasitic wasps to lay eggs in attacking insects.

Speleothems are diverse mineral formations that form in air-filled caves

Speleothems like stalactites and stalagmites form when water deposits minerals after a cave rises above the water table and fills with air. These formations preserve the mineral deposits, which may serve as climate proxies, for as long as a million years.

Visualize the purpose of stomata in photosynthesis

These openings on the underside of leaves can be opened and closed by specialized guard cells to regulate the movement of carbon dioxide into and oxygen out of cells, thus impacting the rate of photosynthesis. At night, when the light-dependent reactions in photosynthesis are not possible, the stomata close to prevent the plant from losing water through transpiration.

Blood color differs across the animal kingdom, with some animals producing blood that appears green (a group of lizards in New Guinea) or blue (horseshoe crabs).

While invasive species typically harm ecosystems by outcompeting native organisms for resources, some provide unexpected benefits, including new shelters, nesting habitats, and reduced environmental heat stress.

Supertoxic rat poisons are wreaking havoc on unintended targets, including predator birds, mammals, amphibians, crustaceans, and insects.

Large animals like giraffes and elephants have evolved unique cancer defenses.

Neural replays in mice help explain food aversions

Princeton University scientists published research in 2025 analyzing how mice learn to associate certain foods or flavors with feeling ill—even when there’s a time gap between eating something and feeling sick. The work, performed with grape Kool-Aid and injections of a substance that made mice sick, traced the literal “gut reaction” of how gut distress signals are linked to neural replays of what the mouse ate.

Learn how to build your own vivarium

Creating a self-contained habitat for plants and microscopic animals requires a careful balance of organisms that maintain a cycle of water, nutrients, and other chemicals throughout. Bottlenecks in these cycles are mitigated through careful construction, such as incorporating a drainage layer to effectively manage water.

Odor blockers use nonpolar oils to trap smelly polar molecules

In the case of feces, gut bacteria produce compounds such as skatole and hydrogen sulfide, which the brain registers as unpleasant. Because oils do not dissolve in water, they can be used to create a layer on the surface that prevents smelly compounds underwater from escaping into the air.