To prevent floating away from others while sleeping, sea otters may wrap themselves in kelp or hold paws, using physical contact to form groups known as 'rafts.'

As part of the up to 15 pounds of seafood they consume daily, sea otters eat urchins that feed on kelp forests—sources of shelter and food to over 800 species—thereby making the marine mammal a keystone species.

To survive underwater hibernation, some freshwater turtles perform cloacal breathing—blood vessels absorb dissolved oxygen from water drawn into the organism's cloaca, or rear orifice.

Across the animal kingdom, parenting can include adults carrying their young, providing their bodies for sustenance, searching for food and shelter for their children, and separating siblings who may eat one another.

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.

While nearly all fish are cold-blooded—their body temperatures match their surroundings—the opah, or moonfish, is fully warm-blooded, with a body temperature about 5 degrees Celsius (9 degrees Fahrenheit) warmer than its environment.

The world's largest species of marine algae is giant kelp, which can grow as much as two feet per day from depths of about 100 feet up to the ocean surface.

As many as 100,000 fire ants can interlock with one another and form a living raft to save their colony when at risk of drowning in rising water.

In recent years, orcas have begun sinking boats and other orcas are following in their footsteps

For just over five years, killer whales have been ramming (and occasionally sinking) expensive yachts, sailboats, and fishing boats in waters near European coasts. Scientists believe these incidents are the result of play rather than aggressive attacks.

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 animals possess sensitive hearing to help pinpoint prey and map the world

Bats and dolphins produce sound to reflect off surfaces and create a mental image of their surroundings. Owls' faces are dish-shaped to help funnel sounds to their ears, including that of mice moving along leaves or snow. Pinnipeds, such as seals and walruses, hear in both air and water.

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

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

Polar bears have black skin to better absorb warmth from the sun, but their transparent, hollow hairs scatter and reflect light so that they appear white.

Although consuming saltwater can dehydrate and kill organisms, some fish survive by using specialized gills that leach excess salt from their bodies back into the surrounding water.

Swimming in schools helps some fish conserve energy in turbulent flows

Scientists studying groups of giant danios swimming in turbulent waters found that the fish used up to 79% less energy than they did when swimming individually in the same conditions. The same fish were found to use the same amount of energy in turbulent and calm water when in schools.

Oxygen and nutrients are circulated in tardigrade bodies through physical movement

Rather than having a circulatory system, oxygen is directly absorbed through their skin and spreads through a fluid called hemolymph as tardigrades crawl. When molting to grow, they shed their outer skin and stylets—sharp mouth parts used to pierce prey—which are regrown in their salivary glands.

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.

Divers capture a blanket octopus unveiling her billowing membrane

In a short clip captured during a blackwater night dive in the Lembeh Strait, a blanket octopus unfolds and displays a colorful web multiple times its original size. The aquatic animal’s iridescent body and tentacles glow against the nighttime...

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.

Over 200 known species hibernate, allowing them to lie dormant and survive harsh periods when water and food become scarce, such as frigid winter months or scorching summer periods.

Despite being multicellular and photosynthetic, organisms such as kelp and sea moss are macroalgae, not plants, because they lack specialized roots and stems to pump water.

Similarities between human and animal sleep

Have you ever noticed the wide-ranging differences in sleep between humans and animals? Sleep as a necessity is present amongst all animal species, but the specific patterns of sleep vary widely. Just think of the differences between how an owl, a whale, and a horse might sleep. This helpful resource from the Sleep Foundation explores the relations between human and animal sleep, complete with some fascinating statistics about sleep patterns throughout the animal kingdom!

Able to hold their breath for up to 15 minutes, beavers are considered keystone species via their construction of dams and formation of wetlands, which serve as homes and food sources for fish, birds, insects, and other animals.

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.

The cells of spotted salamander embryos and early-stage larvae harbor algae that support embryonic development by increasing oxygen levels and removing waste.

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.

Turtles' sense of direction comes from sensitivity to Earth's magnetic field and wave movement

Female sea turtles use this ability to migrate hundreds of kilometers across the ocean from their feeding grounds to the beaches where they were born to lay their eggs. Researchers have found that these turtles can reach these beaches despite ending up significantly off course as they detour away from predators or toward foraging territories.

About 1,500 species of tardigrades have been identified by their unique physiology

Freshwater-bound eutardigrades live on mosses and lichens and are distinguished by variations in the shape and number of claws at the end of their legs. Marine heterotardigrades, which live on algae and deep-sea sediments, have been observed to possess feathers, inflatable appendages, and flagpole-like tails.

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.

The ocean's ability to store carbon long-term is being hindered by marine heatwaves

More than 4,000 robotic floats with biogeochemical data sensors, including oxygen, pH, nitrate, suspended particles, chlorophyll, temperature, and conductivity, have been deployed as part of the Global Ocean Biogeochemical Array. They have identified changes to ecosystem structure affecting the ocean's ability to transport carbon from surface waters into the deep.

Whale falls—dead whales that have fallen to the ocean's floor—can provide enough food to spawn a local ecosystem of deep-sea organisms that lasts for decades.

Why 75% of ocean animals glow

About 75% of ocean creatures can make their own light. It's called bioluminescence—and it all comes down to a special chemical reaction happening inside their bodies.

The Southern Ocean features the Antarctic Circumpolar Current—the largest ocean current on Earth—which encircles Antarctica and creates a unique biogeographical zone.

The deep-sea fangtooth has the largest teeth of any marine species relative to body size

From transparent fish to the heaviest worms on the planet, these seven creepy creatures lurk in the deep sea. Learn all about them and the unique traits that help them survive and hunt.

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

Why do dreamers twitch?

This thought-provoking piece highlights newer research suggesting sleep twitches may not be random dream leftovers, but instead a crucial way our brains map and understand our bodies. From sleeping rat pups to dreaming octopi, this biological mapping system appears universal across animal species.

Yawning helps regulate heat in and around the skull

All vertebrates, including solitary animals, exhibit yawning behavior, and, despite long-standing beliefs, studies show no correlation between yawning and oxygen levels. Contagious yawning may enhance group coordination and vigilance in animals and involves advanced social cognitive mechanisms.

Why hibernating bears don't get blood clots

For mammals, long periods of inactivity can lead to health problems—blood flow slows and pools, veins kink and distort, and clots potentially form. Hibernation takes this risk to the extreme, yet for decades why animals like bears did not exhibit...

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.

Octopuses have taste receptors along their tentacles

Octopus suction cups are filled with modified sensory receptors that can bind with a greater variety of materials and transport a wider array of information, such as flavor, from tactile stimuli. These structures allow the animal to search for food as it crawls the ocean floor.

Watch this octopus win every single Escape Room challenge

Octopuses are famously intelligent, solitary creatures covered in hundreds of chemical-sensing suckers. They're also pretty fascinating pets, and even enjoy playing. The crew at OctoLab put one of its more playful mollusks into four different Escape Room-like cages to see how long it would take for it to escape. Watch this video to see the brilliant, if a bit unsettling, methods the animal uses.

Bears may have evolved natural mechanisms to prevent blood clots during hibernation, an important development, since inactivity typically leads to blood clots in other animals.

What we can learn from how penguins express affection

Pebbling, a term used to describe small acts of love within a relationship, comes from penguins. Male gentoo penguins, a species of penguin that lives on sub-Antarctic islands, present pebbles to their potential mates later used to build nests. This small but helpful act is something we humans can learn from. Think of the “pebbles” you can share with loved ones on a daily basis.

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.

Light pollution is giving oysters insomnia

Oysters, bivalve mollusks that have light-detecting cells along their skin, can't sleep with all this artificial light. According to a 2022 study, oysters' sleep cycles are disturbed by light dimmer than that provided by the full moon. As with humans, it's possible that these bouts of insomnia could have adverse health effects and contribute to the development of disease over time.

Catfish have taste buds spread across their entire skin, making their whole body function like a tongue that can taste food several feet away.

What happens when a whale dies and falls to the ocean floor

A large whale's body can blanket more than 538 square feet of ocean floor. That's an enormous amount of organic matter, providing food for the ecosystem for centuries. Researchers have discovered bones on the seafloor from whale species that have been extinct for over 100,000 years.

Old Thom, the rare solitary orca

This orca has intrigued and perplexed scientists because of its seemingly docile existence separate from other orcas, which are known to be highly social beings.

Visualizing the 75 largest underwater animals

With so many fish in the sea, which are the largest? This infographic shows fantastic illustrations of the 75 largest sea animals, ranked by average size. The detailed visual is organized in descending order of size, starting with the blue whale,...

A pod of orcas takes down a yacht

The pod rammed the boat’s rudder for about 45 minutes. Authorities were able to get crew members to land safely, but their yacht was irreparably damaged. Check out the story and photos here.