Instead of bones, shark skeletons have 200 to 400 structures composed of cartilage—the same material that makes up human ears.

The gene that changes sharks to skates

Sharks and skates (similar to stingrays, without the stinger) look different enough that it's reasonable to assume they aren't related. However, a new study suggests that a microscopic change at the cellular level caused skates to branch off from sharks as they evolved. Scientists believe roughly 285 million years ago, the 3D structure of shark DNA shifted, disrupting the relationships between key genes, and resulting in the flat, symmetrical shape of modern skates.

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.

Rather than removable armor like snail shells, turtle shells are part of the organism's skeleton and consist of 50 to 60 fused bones that grow with the organism.

Why no aquarium has a great white shark

Historically, great white sharks die very quickly in captivity—with the exception of the Monterey Bay Aquarium's successful attempt in 2004. The aquarium held a four-year-old great white for six months. Before that, the longest stint was 16 days. The creatures can only breathe if they are moving forward, making survival difficult in a small tank.

Air sacs and lightweight bones helped some dinosaurs grow to enormous sizes

After the Triassic extinctions, new species with birdlike anatomy evolved from smaller, early dinosaurs. This anatomy allowed for more efficient breathing and lighter skeletons, favoring the evolution of larger organisms.

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.

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.

The animatronic shark from 'Jaws' was a complex machine called 'Bruce.'

How snake biology allows them to eat prey larger than they are

Possessing flexible skulls with elastic ligaments and unfused jaw bones, snakes can open their mouths to engulf much larger prey, and adjustable airways enable them to continue breathing while their teeth grip onto their food. Through slow digestion and specialized cells that decompose bones, some snakes can survive on a single large meal for over a year.

The three smallest bones in the human body—the malleus, incus, and stapes—amplify the vibrations of sound waves by almost 20 times to help enable hearing.

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.

Neanderthals commonly had surfer's ear, a potential sign of extensive seafood collection

Analysis from 2019 found that about half of the 23 Neanderthal skulls scientists examined seemed to have the bony growths in the inner ear, signifying they had surfer's ear. Those growths suggest our ancient relatives, dating back to between perhaps 100,000 and 40,000 years ago, were potentially hunting fish, mollusks, or other marine resources in chilly waters.

'Shark Week' began as a late-summer programming block dedicated to shark conservation and dispelling myths perpetuated by popular media like Steven Spielberg's 'Jaws', but over time, it began incorporating more sensationalized content.

Watch the first-ever footage of a ghost shark

In 2009, the pointy-nosed blue chimaera was filmed swimming in the deep sea. That same year, researchers first observed them off the coast of California and Hawaii, after they had previously been found only in the Southern Hemisphere.

'Jaws' creators regret making sharks the monsters

Both Peter Benchley, the author of the original 1974 novel, and Steven Spielberg, the director of the blockbuster film based on it, acknowledge that the film's popularity has led to the stigmatization of the mostly harmless creatures.

Bone marrow generates roughly 500 billion new blood cells each day.

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

The tongue evolved in animals roughly 350 million years ago

Creatures like fish rely on suction to consume food, flexing their gills to create water currents that vacuum up their meals. The evolution of the tongue enabled vertebrates to completely cut ties with the sea, moving onto land where they could sample new foods and ways to eat them.

See the anatomy of a healthy knee joint, which has smooth cartilage that cushions the joints and protects the bones from rubbing together.

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.

The purpose of narwhal tusks has mystified researchers for centuries

Nicknamed the "unicorn of the sea," narwhals have no teeth aside from two canines that grow directly forward as tusks. For roughly 85% of females, they stay embedded in the bone. For males, they grow into large, spirally tusks that are full of nerve endings and blood vessels. Scientists today believe that tusks likely formed for sexual selection purposes and eventually evolved to assist in other processes, such as hunting.

Unlike the roars in movies, dinosaurs likely cooed, rumbled, and boomed

Fossil evidence and CT scans suggest that many dinosaurs produced low-frequency sounds using resonating crests, closed-mouth vocalizations, or organs similar to those of birds and crocodiles. Larger sounds would not have been helpful for sneakily hunting prey.

Track individual sharks around the world in real time

OCEARCH provides essential data on shark populations and marine ecosystems to support broader conservation efforts. Foster your understanding of marine ecosystems by exploring different species and their movement.

Shooting 'Jaws,' Spielberg went over budget and schedule

The shark flick was plagued with technical issues—many of them due to shooting on the open ocean—causing the director to go over budget by more than $4M. Shooting the film took much longer than anticipated, stretching more than 100 days past the anticipated end date.

Why our ancestors didn't have crooked teeth

The ancient human fossil record is filled with specimens with pretty nice teeth. So why do modern humans have dental problems? Scientists can't be certain, but one hypothesis suggests the evolutionary shrinking of the human jaw crowded our mouths,...

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

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.

Explore the abundance of different types of cells in the human body

Lacking a nucleus and other organelles to maximize space for oxygen-carrying hemoglobin and enhance maneuverability through narrow capillaries, there are about four times as many red blood cells and platelets as all other cell types in the body combined. However, about half of the body's cell biomass consists of skeletal myocytes, or muscle fibers.

A human joint is any place in the human body where two bones connect, providing structure and stability.

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.

Humans won't develop more than 5 fingers because it would impact too many body parts

All modern animals have five or fewer digits on each of their limbs. Roughly 348 million years ago, at least two species had eight: the Ichthyostega and the Acanthostega. According to Dollo's law, complex evolved features are very unlikely to recur in evolution. Researchers believe humans won't develop more than five digits because it would impact other body parts too much.

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.

Everything scientists could learn by looking at your skull

Our skulls are all unique, but they also share characteristics across groups of people. In the absence of fingerprints, forensic scientists can learn a lot about you just from your skull.

Breaking down the knee's anatomy

The human knee is a remarkably complex structure carrying the full weight of the body throughout a person's life while allowing a number of complex twists, flexes, and extensions. It's also one of the body's biggest weaknesses—the location of chronic pain and replacement surgeries for millions of Americans.

T. rex hunted for prey but wasn't above scavenging rotting meat

Despite possessing a huge head full of serrated teeth the size of rail spikes, the Tyrannosaurus rex had puny, rigid arms, and scientists think it enjoyed scavenging.

Human anatomy provides evidence for evolution

Throughout history, scientists have used anatomy to support the Theory of Evolution in three main ways. Homologous structures, or similar physical features in organisms that serve different functions, can help scientists understand common ancestors....