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

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.

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.

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.

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.

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

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

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

An analysis of fossilized reefs from northern Africa and Germany suggests that shallow water corals and photosynthetic algae formed a mutualistic partnership between 419 and 359 million years ago. The discovery was made by analyzing nitrogen-isotope ratios in the fossils, which differ depending on whether algae are present, due to various chemical processes.

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.

Learn how humans can protect coral reefs

When diving and snorkeling in environments containing reefs, avoid touching reefs, anchoring on them, or using sunscreen with active ingredients harmful to marine life. Properly recycling and disposing of trash in bins helps reduce microplastics and chemicals that can run off into wastewater and into the oceans.

How the environmental diversity of coral reefs provides potential medical treatments for humans

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. These include antibiotics, antivirals, and powerful toxins that target the nervous system and are studied for applications involving pain management and neurological treatments.

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.

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.

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.

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.

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.

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.

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

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

An overview of the Coral Triangle, which contains about 76% of global coral species

Spanning the waters of Indonesia, Malaysia, Papua New Guinea, the Philippines, the Solomon Islands, and Timor-Leste, the region contains more than 600 coral species and over 2,200 of the world's coral reef fish species. It sustains 120 million people with food and other resources, as well as a $12B yearly tourism industry.

Multiple species exhibit convergent evolution by developing crab-like features

Various organisms that appear to be different types of crabs, such as porcelain crabs and coconut crabs, have been shown to belong to distinct decapod lineages whose predecessors resemble shrimp or lobsters. Environmental pressures and other factors have caused these species to develop similar characteristics, which nature has shown are beneficial to survival.

What animals live in the ocean?

The oceans host an incredible diversity of fascinating species. Oceana's Marine Life Encyclopedia beautifully presents facts and photos of ocean animals from Atlantic Cod to Zebra Sharks.

When caught in the mouths of cardinal fish, seed shrimp release glowing, bioluminescent chemicals, which alert predators of the cardinal fish, prompting the shrimp's ejection.

Turning some invasive species into cash crops has helped control their spread

In Mexico, some companies are transforming sargassum seaweed blooms into paper, bricks, and shoes, while in Cambodia, water hyacinths are dried and woven into baskets, rugs, and other crafts. Lionfish and green crabs have been hunted for culinary dishes, with the latter also being used to make crab whiskey in New England.

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.

When caught in the mouths of cardinal fish, seed shrimp release glowing, bioluminescent chemicals, which alert predators of the cardinal fish, prompting the shrimp's ejection.

Deep sea fish rely on a molecular strengthener to prevent being crushed

Trimethylamine N-oxide (TMAO) stabilizes hydrogen bonds and prevents water and proteins within organisms from being misshapen under immense pressure. Compounds called piezolytes protect cellular membranes from being crushed in regions like the Mariana Trench, where pressures are 1,100 times greater than surface atmospheric pressure.

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.

Fungi can cause disease, but they’re also our planet’s key decomposers

Fungi are their own taxonomic kingdom separate from flora and fauna, acting as the key decomposers and nutrient recyclers for our planet. Watch this video to understand the diverse types of fungi and the stages of the fungal life cycle. This video illustrates how fungi species may spread, eat nematode worms, damage nearby plants, and much more.

Learn about photoautotrophs, the photosynthetic organisms at the base of the food web

The sun is the ultimate source of energy for the planet, but consumers along food chains, such as herbivores and carnivores, cannot harness this energy themselves and instead rely on consuming plants and other organisms that capture it to build carbohydrates. Besides plants, photoautotrophs include algae and some bacteria that convert solar energy into chemical energy for the biosphere.

Bees are crucial for pollination and food security

When animals and insects pick up the pollen of flowers and spread it, they allow plants, including many food crops, to reproduce. The most common pollinator is the bee, but bees are at risk from pollution and pesticides.

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

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

Watch how deep-sea mining equipment collects and processes polymetallic nodules—metal-rich, potato-shaped rocks—from the ocean floor and creates environmentally damaging plumes of sediments.

Hotels in Cannes, the glamorous city on the French Riviera, hire hawks to ward off seagulls during the city's famous film festival.

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

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.

The animatronic shark from Steven Spielberg's 'Jaws,' the first modern blockbuster, was a complex underwater apparatus called 'Bruce.'

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

Crows are believed to have intelligence on par with a seven-year-old child and demonstrate complex behaviors, from problem-solving with tools to recognizing human faces.

Hedge funds, the private investment firms that trade a wide swath of financial assets, make money by imposing steep fees on investors and from the fund's investment performance.

Doctors differentiate between a phobia and fear by asking patients whether their fear interferes with their day-to-day activities.

Some renewable energy sources may weaken the resiliency of electric grids by removing outage buffers provided by coal- and natural gas-fired plants, which provide the system with more time to find a new power source if a plant goes down.

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.

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.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

Some coin denominations have ridges etched on their sides, partly to prevent counterfeiting, in a practice called 'reeding.'

Iran's Revolutionary Guard Corps is independent of Iran's regular army and is one of the most powerful and influential military-political organizations in the Middle East.