10 Jaw-Dropping Shark Facts That Will Change the Way You See Them

Nothing strikes fear in the hearts of humans like a shark fin in shallow water. They are often portrayed as silent killers, scouring the ocean for prey. Their cold, fearsome reputation has influenced pop culture and led to media phenomena like “Shark Week.” While they may be some of the most fearsome predators in the ocean, there is more than meets the eye when it comes to sharks.

Sharks are among the oldest creatures on Earth, equipped with unique adaptations that have helped them hunt successfully for hundreds of millions of years. Although they are powerful predators, sharks play a crucial role in maintaining the balance of ocean ecosystems. No matter how you look at it, sharks are among the most remarkable creatures in the world. Let’s explore 10 fascinating facts that will change the way you see these ocean predators.

Sharks Have a Sixth Sense

Whereas most predators hunt prey using senses like touch, hearing, and sight, sharks are equipped with an extra sense: electroreception. Sharks can detect electric signals in the ocean using an organ called the Ampullae of Lorenzini. These are jelly-filled pockets and canals connected to open pores on their heads. Filled with nerve fibers, these sensors use the conductivity of seawater to detect electrical currents as small as 5 billionths of a volt per square centimeter. That’s the equivalent of sensing electrical differences as if “two AA batteries were connected 10,000 miles apart.“

Their Skin is Like Teeth

Shark skin may look like scales, but it is actually more like teeth. Their skin is covered in small, flat, V-shaped scales called dermal denticles. These miniature teeth protect sharks from ectoparasites and predators, as well as decrease drag and friction. This unique skin structure is so efficient that Olympic swimsuit designers have created fabric that mimics dermal denticles to improve speed.

Coconuts Kill More People than Sharks

Every year, the news runs stories about tragic shark attacks on humans. While these stories are frightening, they are also misleading. In reality, shark attacks are incredibly rare. So rare, in fact, that you have a greater chance of being killed by a falling coconut. While certain researchers have disputed this claim, the fact remains: sharks typically kill fewer than 10 people per year worldwide, whereas more innocuous, commonplace things result in far more deaths annually. Motor vehicles, for example, result in approximately 40,000 to 45,000 deaths per year in the United States. In terms of animals, elephants are estimated to kill between 100 and 500 people per year.

Thousands of Teeth

Most humans lose their baby teeth and grow a single set of 32 permanent teeth. Sharks, however, keep producing teeth for their entire lives. If a shark loses a tooth, a new one grows to promptly take its place. A look inside a shark’s mouth will show you several rows of teeth. All the rows behind the first are backups, ready to replace any lost front teeth. This means that these predators can lose thousands—and in some species up to 30,000 teeth in a lifetime—without affecting the appearance of their ferocious smiles.

Interestingly, some shark species, such as whale sharks, are filter feeders. This means they suck in water containing small organisms like plankton, which get trapped in their gill rakers and are then consumed. Whale sharks have teeth, but they are vestigial; these teeth once served a feeding purpose but have since become evolutionary relics.

Nearly a Third of Shark Species Are Threatened with Extinction

Sharks’ numbers are dwindling at an alarming rate. The IUCN Red List reports that about one-third of shark and ray species are threatened with extinction due to overfishing, habitat loss, and climate change. Bycatch—when sharks are unintentionally caught while fishing for other species—is another factor contributing to their declining populations. Well-known species like the great hammerhead shark are critically endangered, while the sand tiger shark is classified as endangered.

Scientists Age Sharks Like Trees

For a long time, scientists have aged sharks the same way they age trees—by counting the rings of their vertebrae, similar to the rings inside a tree trunk. A shark’s vertebrae are made up of concentric pairs of opaque and see-through bands. By counting band pairs, scientists could determine a shark’s age; if a shark’s vertebrae contained 10 pairs, it was likely 10 years old. In 2018, however, researchers at the National Oceanic and Atmospheric Administration discovered that this counting method is not definitive. It turns out that band pairs in a shark’s vertebrae are deposited at different rates over time. While the tree-ring-counting method still holds for sharks under two years old, scientists have adopted new techniques to better understand the depositing rate of these vertebral bands.

Boneless

Not all sea creatures have bones. Take sharks, for example. They belong to a classification of fish called elasmobranchs. These fish have internal cartilaginous tissue akin to ear or nose tip cartilage, which is lighter than bone and helps them stay buoyant in the water. While these predators may not have bones, their cartilage frames can still fossilize. As sharks age, they strengthen their skeletons with deposits of calcium salts. This is why a dried shark skull or jaw feels heavy and thick, similar to bone. Unlike the rest of the shark’s skeleton, which is made of cartilage, shark teeth are composed of dentin and enamel, allowing them to fossilize surprisingly well.

Sharks Are Older Than Dinosaurs

The earliest known dinosaurs appeared between 250 and 200 million years ago during the Triassic Period. Sharks, however, are much older, appearing in the fossil record over 450 million years ago during the Silurian Period. This means sharks are older than even insects. The closest equivalent to the modern shark comes from shark-like teeth found in a 410-million-year-old Devonian fossil from an ancient creature called Doliodus problematicus. Scientists aren’t exactly sure how sharks managed to survive five mass-extinction events, but it likely has to do with genetic diversity, hardiness, and an ability to exploit different parts of the water column (deep ocean, shallow water, and river systems).

Hammerhead Sharks Have 360-Degree Vision

Some shark species, such as the hammerhead shark, really do have eyes in the back of their heads. Thanks to the positioning of their eyes on the sides of their hammer-headed shape, hammerhead sharks have 360-degree vision in the vertical plane. This means they can see everything going on above and below them. Not only does their hammer-shaped head help them see in all directions, but it also provides extra depth perception and allows these predators to move their heads quickly.

Some Sharks Can Reproduce Without a Partner

Many shark species may be endangered, but some have an almost miraculous ability to combat their dwindling numbers: virgin birth. In rare instances, some sharks, like the endangered smalltooth sawfish, undergo a process called parthenogenesis. This occurs when females fertilize their own eggs with a part of the egg that separates during division and then fuses back to the egg. Similar to cloning, parthenogenesis allows creatures like sharks to reproduce without a mate. Scientists aren’t exactly sure why this happens, but some theories suggest that this self-reproduction process is triggered by an absence of males in the area.