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

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.

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....

View a gallery of animals found on abyssal plains, hydrothermal vents, seamounts, and other deep-sea habitats.

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.

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

Cold-blooded reptiles seek heat, and that behavior may help combat fungal infections

This Radiolab podcast episode takes on the idea that though our human bodies are too warm for the majority of fungal species to effectively replicate inside our bodies, that's not the case for reptiles. Yet when those species warm their bodies by basking in the sun on rocks, they can soak up heat and may also help keep fungal infections in check.

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.

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.

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.

The halting of human bone growth helps manage heat produced from metabolism

While fish, amphibians and reptiles get bigger throughout their lives until they die, their slower metabolisms allow their bodies to regulate the resulting smaller temperature increases. In humans, hormones triggered during puberty harden growth plates, ending bone lengthening.

View thermophiles found in Hot Springs National Park, including nanobacteria and ostracods

Most organisms in this subset of extremophiles live at temperatures between 60 and 80 degrees Celsius (140 to 176 degrees Fahrenheit), which is hot enough to unfold proteins needed for most biochemical reactions. In thermophiles, these molecules, including those needed to replicate DNA during cellular division, are tightly packed and held by stronger bonds to resist changes in shape.

Atmospheric greenhouse gases trap thermal energy and make Earth habitable

The moon and Earth are at the same distance from the sun, but the moon experiences large fluctuations in surface temperature because it lacks an atmosphere to insulate it. Gases such as water vapor, ozone, carbon dioxide, and methane can intercept about 90% of the infrared radiation emitted by Earth's surface.

The Amazon molly is an all-female organism that has been cloning itself for 100,000 years without accumulating harmful mutations.

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.

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.

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.

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.

Feels-like temperature indicates how our skin will feel

When the wind is moving faster, we tend to feel colder due to the so-called "wind chill," which cools our bodies by moving heat away from them and making water evaporate faster. On the other hand, high levels of humidity can make us feel 10 degrees warmer at times.

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.

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.

Why do you shiver when cold?

Humans are warm-blooded creatures, so our bodies like to maintain internal temperatures separate from and typically above those in their environment. This is made possible by a process known as thermoregulation. When the brain's hypothalamus senses a drop in the body's core temperature, skeletal muscles may be ordered to shiver, sending out waves of muscle contractions and exothermic biochemical reactions whose byproduct includes heat and energy.

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.

Most fungal pathogens can't survive the heat of our bodies.

Normal body temperature varies from one person to another; it's not uniformly 98.6 F, as physician Carl Wunderlich determined in the 1800s.

Compared with crocodiles, alligators are typically smaller, darker-colored, possess a more U-shaped snout, hide the fourth tooth on their lower jaw, have webbed feet, and can move their tongues.

38 thought-provoking facts about the ocean

Coral produces its own sunscreen, tsunamis move at 500 miles per hour, one of the loudest sounds ever recorded came from an ice quake, and other interesting facts collected from sources such as National Geographic and NASA.

A look at hydrothermal vents, where barophiles and hyperthermophiles survive boiling water

Discovered in 1977 during an exploration of the Galapagos Rift, these seafloor openings spew hot magma and chemicals that heat seawater to hundreds of degrees. Without the sunlight found at depths of less than 1,000 meters (3,281 feet), extremophiles in these environments convert released chemicals into energy to survive, alongside surviving extreme pressures.

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.

Dive into the ocean's hottest water to explore hydrothermal vents

What can live at temperatures of 700 degrees Fahrenheit under skull crushing pressure with zero sunlight? Meet the animals living in the most extreme conditions on Earth in this four-minute video.

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.

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.

The Ocean Observatories Initiative aims to provide freely accessible, real-time ocean data for up to 30 years to help scientists identify and analyze short- and long-term ocean processes.

Bioluminescence provides organisms with a method of hunting, defense, or mating

Unlike glow sticks, bioluminescent reactions use renewable resources like oxygen and ATP. This ability allows fireflies to mate and deter predators, anglerfish to confuse and attract prey, and deep-sea shrimp to defend themselves by vomiting glowing slush.

One jellyfish species is biologically immortal

Turritopsis dohrnii is a type of jellyfish that can revert back to a juvenile stage after reaching sexual maturity, theoretically allowing it to stay alive for good. But that's a tough sell in a world full of predators. See this list of some of the longest-living species on Earth.

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.

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.