The origin of the symbiotic relationship between corals and the algae that feed them

Coral reefs get their colors from zooxanthellae—microorganisms that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

Coral reefs get their colors from zooxanthellae—microorganisms that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

The marine animals that rely on coral reefs for habitats, camouflage, and food

Parrotfish and surgeonfish feed on algae that grow on coral reefs to prevent overgrowth while serving as prey for larger fish across the food chain. Reefs also serve as structures for organisms like sea anemones, which provide shelter for clownfish, and homes for invertebrates such as crabs, lobsters, and shrimp, which help recycle nutrients.

Learn about deep water corals and the coral gardens they slowly build in the dark

Found throughout the world's ocean basins at depths beyond 200 meters (660 feet), these corals do not rely on photosynthetic organisms for nutrients and instead rely on food that's fallen from the ocean surface. Beyond forming larger reefs over the course of thousands of years, smaller coral gardens are built with the aid of underwater worms.

The first appearance of bioluminescence was at least 540 million years ago

After analyzing fossils, genetic data, and statistical methods, scientists believe octocorals were the first organisms to evolve light-producing abilities. As a result of independent evolution across at least 94 species, this phenomenon is connected to a diverse range of behaviors.

The importance of coral reefs since their first appearance hundreds of millions of years ago

Formed from calcium carbonate skeletons deposited by hard corals, some estimates suggest these reefs provide habitats for over a million marine species. Spanning massive areas, coral reefs also serve as buffers against extreme weather, such as tropical storms.

How climate change threatens coral reefs, including via warming and acidification

Increasing ocean temperatures disrupt the symbiotic relationship of corals and algae, causing the former to bleach and weaken, and strengthen storms that can destroy reef structures. Higher greenhouse gas emissions increase dissolved carbon dioxide levels in ocean water, triggering a series of reactions that consume carbonate, a key ingredient in coral reef construction.

Niagara’s bedrock holds 440-million-year-old coral fossils

The Lockport Dolomite that caps Niagara Falls is composed of fossilized coral reefs from a tropical sea that once covered the region 440 million years ago.

Artificial coral reefs have been 3D printed from nontoxic, biodegradable terracotta clay, which coral polyps have used as a foundation for rebuilding marine ecosystems.

Watch a time-lapse of hard coral growth, which forms coral reefs

Over several weeks in an aquarium, these staghorn coral polyps grew and produced new polyps as they deposited calcium carbonate, which forms the basis of coral reefs. At the 0:28 mark, you can see coral growth healing a damaged branch.

Artificial coral reefs have been 3D printed from nontoxic, biodegradable terracotta clay, which coral polyps have used as a foundation for rebuilding marine ecosystems.

The anatomy of coral polyps, whose mouths consume food and expel waste

The mouth is surrounded by tentacles that help clear away debris and defend the organism, using stinging cells called nematocysts that resemble those of jellyfish. Connective tissue called coenosarc connects individual polyps within colonies and allows them to share nutrients.

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

Layers in sediment cores hold clues to Earth’s past climate

By analyzing materials such as pollen and algae within the layers of these cores, which are collected from lakes and oceans, scientists can learn what the environment and climate were like when that layer formed.

Billion-year-old Arctic fossils suggest Earth had fungi far earlier than previously thought

Named Ourasphaira giraldae, this new species of fungus, reported in 2019, was found in the Grassy Bay Formation in the Canadian Arctic. It pushed the fossil record of fungi back by about half a billion years since the oldest previously recognized fungi fossils came from the Rhynie chert, a Scottish site that dates back roughly 400 million years. This fungal discovery also suggests that fungi may have occurred on land much earlier than plants, raising questions about what ancient fungi used for nourishment.

Coral polyps reproduce via broadcast spawning, where entire reefs simultaneously release reproductive cells for about one hour, once a year.

The history of Earth's breathable atmosphere, made possible by photosynthetic bacteria

Between 3.2 billion and 2.8 billion years ago, threadlike microorganisms called cyanobacteria began consuming available water vapor, carbon dioxide, and sunlight to produce oxygen. However, molecules released from Earth's interior by volcanoes consumed this oxygen via chemical reactions, preventing it from accumulating until volcanism had sufficiently decreased about 2.4 billion years ago.

Fish populations in the Great Barrier Reef have increased after installing waterproof speakers on the ocean floor that played recordings of sounds from healthy coral reefs.

Fossils form in environments where dead organisms can be rapidly buried

Such landscapes enable corpses to be encased by terrain before significant decay occurs. They are most commonly found in river deltas and sinking coastal regions, where sediments accumulate over time until geological forces expose the areas to erosion, revealing embedded fossils.

The Southern Ocean's powerful circular current isolates organisms in its environment

The spiralling current churns up nutrients across the frigid waters, leading to the evolution of fantastical organisms, including century-old starfish and colossal squid, and unique adaptations, including the icefish's clear blood and organic antifreeze, over the past 30 million years.

What revisiting a 1979 experiment reveals about ecosystem recovery after deep-sea mining

A 2023 study co-led by the National Oceanography Centre and the Natural History Museum, London, found that tracks made by the mining vehicle remained largely unchanged since 1979. Small animals, such as amoeba-like xenophyophore, were seen in the cleared areas, but sightings of larger animals known to live in the region were much rarer. (Some readers may experience a paywall.)

Research has shown that bioengineered algae can help remove microplastics

Scientists at the University of Missouri found that, like microplastics, some algae are particularly hydrophobic—they repel water—and that both can clump together to form a microplastic-algae sludge, which can then be collected to remove microplastics from water. Researchers believe this algae provides a scalable solution for microplastic removal that can be employed in wastewater treatment processes.

Aerial photos of red tide off the Gulf Coast

The toxic algae grows naturally in warmer oceans in small amounts and is typically harmless. With extended warm periods and unusually-high additions of nutrients from run-off, the algae blooms extensively, posing health risks to wildlife and humans...

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.

Coevolution of pollinators and flowering plants diversified both

The first pollinators were beetles, which consumed pollen before flowering plants existed. Over time, plants evolved to attract more insects and improve the uptake of pollen, while insects adapted their biology to enhance the capture of pollen, such as developing specialized mouthparts.

See how each of the more than two million known species relates to each other—and to common ancestors—in this zoomable tree of life.

See how each of the more than two million known species relates to each other—and to common ancestors—in this zoomable tree of life.

Massive blooms of microscopic plankton called dinoflagellates produce the neon blue light seen in glowing tides.

Some organelles are believed to have once been independent cells

Mitochondria and chloroplasts, which are both responsible for energy production in cells, have DNA distinct from that of their host cells and are surrounded by cellular membranes resembling those of bacteria. Through symbiogenesis, these and other specialized structures were absorbed into larger cells, forming the modern-day biological units.

Explore the history, structure, and species of Australia's Great Barrier Reef with this interactive journey narrated by Sir David Attenborough.

Symmetric patterns of magnetic stripes seen on either side of mid-ocean ridges

The symmetry provides evidence of seafloor spreading, where new oceanic crust is created at mid-ocean ridges, which pushes older ocean crust away on either side. Matching the pattern to magnetized material in rocks on Earth’s surface provided a timeline of ocean floor recycling.

Scientists first observed a sperm and an egg uniting in 1876

Throughout human history, scholars and researchers have speculated on the origin of human reproduction. It wasn't until the late-19th century that the physical process of egg fertilization via sperm cells was observed (in sea urchins), forming the basis for modern fertility research.

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.

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 term 'algorithm' originated from the Latinized name of al-Khwārizmī, a 9th-century mathematician whose works introduced Arabic numerals and the decimal-based numeral system to Europe and whose treatise 'Al-Jabr' gave algebra its name.

An investigation suggests a Scottish island became awash in forever chemicals via seafoam and seaspray—raising questions about what that means for the safety of other coastal areas.

Learn more about the history of fireworks, which dates back to an accidental invention during an alchemist's quest for information about immortality.

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.

Scientists testing how climate change affects plants found, in a years-long simulation study, that poison ivy grew 70% faster with the resulting extra carbon dioxide.

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

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.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

The first line of 'immortal' human cells, which can divide indefinitely and are used in scientific research, was nonconsensually taken from a Black woman.

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

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.

A researcher recently discovered an interview from 1967 between groundbreaking journalist Joan Didion and the Grateful Dead, years before the band became an institution.

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

Georgia O'Keeffe's flower paintings are often assumed to be sexual, though the artist claimed she was simply interested in highlighting the beauty of flowers that most people neglect

While the first exchange-traded fund (a 'basket' of different assets that can be bought and sold on a stock exchange) in the US only launched in 1993, the global ETF market has grown to more than $10T in the short time since.