Watch a time-lapse of staghorn coral polyps—a type of hard coral—over several weeks in an aquarium, slowly forming the foundational component of a coral reef.

Through coral IVF, researchers have collected coral eggs and sperm from healthy reefs, grown baby corals in lab pools, and then released them to help repopulate damaged or lost reefs.

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.

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

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

Deep water corals—located throughout the world's ocean basins at depths beyond 200 meters (660 feet)—slowly build small coral gardens in the dark with the help of underwater worms.

The first coral reefs formed hundreds of millions of years ago from the carbonate skeletons deposited by hard corals.

Over 1 million fish, marine mammals, and invertebrate species depend on coral reefs for habitats, camouflage, and food.

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.

Research has found that when their symbiotic algae are not producing oxygen via photosynthesis, corals twirl hairlike structures to circulate water and draw oxygen into their outer tissues.

Some corals absorb harmful ultraviolet radiation and re-emit it as visible light, thereby protecting symbiotic algae within their tissues and providing them with energy for photosynthesis.

The world's largest coral, as seen from space

The world’s largest individual coral colony—measuring over 100 feet wide and 100 feet long—was discovered in the Solomon Islands. This coral is so large it can be seen from space, and is estimated to be between 300 and 500 years old. The coral's size and health provide hope amidst a global coral bleaching crisis, wherein three-quarters of coral reefs have experienced significant bleaching in recent decades. See the photos from space and learn more here.

A simple infographic explaining how coral bleaching works

When corals are stressed by changes in conditions such as temperature, light, or nutrients, they expel the symbiotic algae living in their tissues, causing them to turn completely white.

Inside Australia's National Sea Simulator, scientists are cross-breeding coral species and using CRISPR to genetically engineer heat-resistant corals to withstand warming reefs worldwide.

The three types of coral reefs—fringing, barrier, and atoll—are categorized by where they form.

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

Watch a diving expedition through the world's longest coral colony, which spans more than a football field and whose exact location is kept secret for its protection.

During coral bleaching, corals sacrifice their food source and expel colorful microorganisms to protect themselves, a phenomenon that resembles an organism's immune system attacking itself.

An analysis of fossilized reefs from northern Africa and Germany suggests that shallow water corals and photosynthetic algae formed the mutualistic partnership seen today between 419 and 359 million years ago.

Why are coral reefs important?

Coral reefs are vital ecosystems that millions of people and countless species depend on. This two-minute video from London's Natural History Museum looks at the ecological and economic significance of coral reefs, including their biodiversity and...

Can coral live in cold water?

Dive deep beyond the sunlit coral reefs, and you'll discover a world of deep-sea corals. This article from the National Oceanic and Atmospheric Administration (NOAA) explores the ecosystems of deep-sea corals found way below the water's surface....

Synthetic pheromones may protect coral reefs by attracting their predators

Researchers in Australia and Japan have developed these nontoxic chemicals to attract crown-of-thorns starfish, which consume corals that make up the Great Barrier Reef. As of 2026, synthetic pheromones have been shown to be effective in lab trials, and future field trials will attempt to lure starfish into areas for mass removal.

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.

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.

View a collection of glass sculptures of corals threatened by fishing and deep-sea mining.

Climate change threatens coral reefs by disrupting the symbiotic relationship between corals and algae due to rising ocean temperatures.

Take a 3D underwater trip near the Great Barrier Reef

The Great Barrier Reef is the world's largest coral reef system, comprising more than 900 islands and almost 3,000 individual reefs. This video lets you tag along with divers as they explore the reef off the southern coast of Lady Elliot Island in full 3D (use the direction buttons in the upper left of the video, or your keypad).

From 2023 to 2025, coral reefs experienced their fourth global bleaching event and the largest such event through 2025.

View a collection of images and videos of coral reefs from around the world.

Explore coral reefs in Google's "street view"

Expanding its mission to map the world, Google Maps partnered with The Catlin Seaview Survey to introduce the first-ever underwater panoramas, making oceanic marvels like the Great Barrier Reef accessible to everyone. With Google Maps, the public...

Watch a two-year time-lapse of a pinecone seed transforming into a pine tree.

Decommissioned oil rigs have been repurposed into artificial reefs that serve as nursery habitats for fish, corals, sponges, and other invertebrates in the decades since their installation.

Watch a salamander grow from fertilization to hatching

New microscopy techniques have allowed scientists to image the development of animal embryos with unprecedented detail. This six-minute time-lapse reveals the development of a salamander from initial fertilization to hatching from an egg.

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.

Fungi have been used to restore island habitats in the central Pacific

After removing 1.5 million invasive coconut palm trees and eradicating the black rats that fed on them, as well as seabirds and crabs, conservationists working with the US Fish and Wildlife Service identified areas where fungi could be transplanted to provide nutrients to native trees. These trees serve as nesting sites for seabirds whose guano nourishes coral reefs.

About 76% of global coral species are found in the Coral Triangle—a region spanning the waters of Indonesia, Malaysia, Papua New Guinea, the Philippines, the Solomon Islands, and Timor-Leste.

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

Take an interactive dive and see the animals that populate the oceans, from coral near the surface to shrimp-like organisms near the seafloor.

Take an interactive tour through Australia's Great Barrier Reef, featuring spherical panoramas of marine wildlife, including manta rays, loggerhead turtles, and bottlenose dolphins.

Explore a map of coral reefs around the world and the extent of coral bleaching.

Pearls form when a saltwater oyster or a freshwater mussel coats a parasite or other irritant that has entered its shell with concentric layers of calcium carbonate and organic protein.

Underwater nighttime photos capture the ocean's diversity

Self-taught photographer Steven Kovacs explores Palm Beach's ocean after sunset, capturing tiny sea creatures in deep waters. Over eight years, he's dived into Florida's eastern coast, drifting from 0 to 100 feet, photographing rarely seen larval fish. Lacking formal marine biology training, Kovacs collaborates globally to identify species like cusk eels and the female blanket octopus, known for its revealing membrane. Check out his photos here.

The National Oceanographic and Atmospheric Administration estimates that US commercial and recreational fisheries valued at $200M depend on coral reefs, which provide up to $1.8B in flood protection by absorbing 97% of wave energy.

The Turritopsis dohrnii jellyfish can reverse its life cycle

Discovered in the 1980s, this creature has been dubbed the "immortal jellyfish" for its ability to revert from medusa to polyp form and back, preventing it from dying of old age. However, the jellyfish remains prey to fish and turtles and is defenseless to sea slugs as a polyp.

Meet siphonophores, breathtaking jellyfish-like organisms

Siphonophores are colonial jelly-like creatures made up of specialized segments that work together as one. They're fairly unknown despite being a significant sea predator. Sink into their strange beauty with this video.

When diving and snorkeling in environments containing reefs, avoid touching reefs, anchoring on them, or using sunscreen with active ingredients harmful to marine life.

Hurricanes can grow by replacing their eyewall

A second outer eyewall can form around the primary eyewall surrounding a hurricane's eye. During an eyewall replacement cycle, the outer wall can weaken, collapse, and replace the inner wall, temporarily weakening the storm before it strengthens and grows.

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

Watch a time-lapse from space of photosynthesis across Earth

Using NASA satellite imagery, carbon absorption can be tracked and serves as a proxy for photosynthetic activity on land and in the oceans. Over the course of a year, seasonal changes can be observed as plants become dormant in the fall and active again in the spring.

Studying the circadian clock of a tiny swimming polar creature may help forecast polar ecosystem health

A 2025 study found that Antarctic krill, a food chain staple in the Southern Ocean, have an internal biological clock that helps regulate its swimming patterns and helps the tiny shrimp-like animals adapt to daily and seasonal environmental changes. Better understanding of how the clock and light cues interact may help scientists understand how well the species will respond to pronounced climate change in the polar region.