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.

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.

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.

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

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.

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.

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

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.

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.

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.

Some marine life can survive the extreme pressure of the deep ocean because of specialized molecules that strengthen proteins, enzymes, and cellular membranes.

An overview of extremophiles and the biochemical adaptations employed by various types

These organisms thrive in environments that would normally be inhospitable to most living things by using molecules that help counter deadly environmental factors. These include antifreeze-like proteins that prevent psychrophiles from freezing and rupturing in polar regions, and osmoprotectants that prevent some extremophiles from losing water to salty environments.

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

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....

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.

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

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.

Biofluorescent animals—those that absorb light, such as ultraviolet rays, and re-emit other types of light, such as neon green—include some flying squirrels, scorpions, sea turtles, and platypuses.

There are at least 6 fascinating examples of mind-controlling parasites

Parasitic organisms—including flatworms and barnacles, not just fungi—can modify animal behavior. They can give rise to dancing fish, pulsating snails, suicidal rats, and more. Though some of these pathogens can sicken humans, there is no strong evidence that any can control human 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.

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

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

Bacteria use chemical signals to communicate and coordinate with one another

Through a system called quorum sensing, bacteria produce and absorb compounds from their environment to identify allies or competitors and adjust their behavior accordingly. Some bacteria produce food-digesting enzymes only in the presence of similar bacteria, thereby preventing competitors from consuming their meal.

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.

Some invasive species' populations have been controlled by turning them into cash crops that can be harvested and sold to produce useful materials.

Starting with red, colorful objects will appear to lose their colors the deeper they are submerged because water scatters light, reducing the amount available to reflect off objects and be observed.

Read the 2012 study about captive orcas and the threat of mosquito-borne illness

Written by orca trainers who went on to become scientists, it states mosquitoes bite orcas at night when the animals hang out close to the surface. What's more, antibiotics used to keep captive orcas healthy also may depress their immune response, boosting the risks of them being unable to fight off diseases like West Nile Virus and encephalitis, which have killed orcas at US water parks.

Fish in polar waters contain proteins in their blood that act as antifreeze, and some manufacturers have used lab-grown versions of these proteins to help keep ice cream smooth.

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.

Scientists have found that the Great Barrier Reef's microbiome includes an estimated 362,802 distinct viruses and 876 distinct bacterial and archaeal species—584 of which had never been documented before 2026.

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

Sea stars are invertebrates—they lack a backbone—and while most exhibit pentametric radial symmetry due to having five arms radiating from a central disk, some can possess more than 40.

Advanced drugs are closing in on cancer's deadliest mutations

The protein KRAS, mutated in many cancers, was deemed ‘undruggable’. Now scientists are hoping to save lives with a batch of new compounds that target it.

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.

By targeting a diverse range of sick and injured marine life, sharks—a type of predatory keystone species—help keep ocean gene pools healthy and promote biodiversity by keeping prey species in check.

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

Bacteria rapidly evolve (and share) new defenses against drugs they encounter

Unlike humans, bacteria rapidly make genetic changes in response to their environment, including creating defense against antibiotics. Furthermore, these defenses are passed on to their future generations and can even be shared with neighboring bacteria through horizontal gene transfer.

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.

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.

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.

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.

View illustrations of bioluminescent functions in marine organisms

Bioluminescence can startle predators, camouflage, lure prey, confuse rivals, or facilitate mate recognition. One tactic—the burglar alarm—involves an organism releasing light to attract a larger predator to its attacker as a means of defense.

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.

Because it is observed in organisms that are not closely related, biofluorescence is thought to have emerged independently many times in nature—over 100 in fish alone.

Superbugs evolve defenses against medication, then share them with neighbors

One reason antibiotic resistance spreads so quickly is that bacteria have multiple mechanisms allowing them to share genetic material. This short video offers a concise explanation for each of these mechanisms, and animation that helps viewers understand how antimicrobial resistance can quickly spread from one organism to another.

The hormone that spreads love and helps fish share fear

Scientists consider emotions like fear and empathy to be among the oldest evolutionary behaviors observed in mammals. Yet to date, how these reactions are processed in the brain, regardless of species, is not well understood. A new study reveals how the chemical oxytocin—known as the "love hormone" in humans—helps let fish know when their friends are in danger.

How scientists are using molecules found in acidophiles to develop new medical treatments

The Berkeley Pit, an open-pit copper mine in Butte, Montana, that ceased operations in 1982 and is now filled with highly acidic water, is home to various species of fungi and yeast. These extremophiles produce unique compounds that may have anti-inflammatory benefits and have already been used to create an antibiotic for staph infections.

Breaking down the challenges of alkaline environments and how extremophiles survive them

These areas are far less acidic than the interiors of most organisms' cells, and this imbalance draws protons that are needed for various metabolic processes, including energy production, out of cells. To counter these effects, some alkaliphiles have developed stronger proton regulation across their cellular membranes and proteins that drive these processes with greater stability amid such acidity imbalances.

Molecules derived from algae can be found in foods such as ice cream, salad dressings, brownie mix, and gravies, as well as in products such as toothpaste, multivitamins, and egg substitutes.

Bioluminescence became common in the ocean to support survival in dark environments

Despite seeming like a rare ability in land animals and unseen in plants, bioluminescence has evolved at least 29 times across marine species, indicating its necessity for survival where hiding spots are rare and highlighting how environments provide evolutionary pressure.

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.