Incredible Facts About Sharks
Just like dinosaurs, sharks capture the imagination of people no matter how young or old they may be. And for good reason. Sharks are some of the strangest and most wonderful creatures in the world.
These fish can be large or small, gray or pink, docile or a bit hostile. They have been around for millions of years and have adapted to their environment in some amazing ways to hunt, swim and live.
That's not all. From great white sharks and megalodons to goblin sharks and sharks that glow in the dark, you'll find some new facts about sharks that you didn't know before. You also might need a bigger boat.
There Are Over 500 Species of Shark
There are many different types of sharks, and they come in a range of sizes, from small to absolutely huge. The basking shark, for instance, is typically 26 feet long and weighs up to seven tons.
Other sharks are small, like the smoothhound shark, which grow to be about 15 inches long and munch on bony fish.
Sharks Embryos Devour Each Other
Sharks start predation before they are even close to having consciousness. Shark embryos from tiger sharks will eat one another in the womb.
That's because female sharks can be impregnated by multiple fathers simultaneously, creating multiple embryos from different fathers in the womb. The biggest embryo will chow down on the other embryos, leaving just one embryo from one father. It's theorized that this cannibalism makes sure that only one father's gene remains dominant.
They won't always eat the entire pack, though. Sometimes a tiger shark gives birth to two babies.
Some Sharks Have to Keep Moving
Are sharks the predator that never sleeps? Kind of. Some sharks have to keep moving to keep water flowing over their gills so they can breathe. Their brain goes into a sort of sleep mode and their body keeps chugging along.
Other sharks, like Caribbean reef sharks and lemon sharks will lay about on the ocean floor in what appears to be a resting period.
Whenever a shark does rest, its eyes remain open. It's not sleep in the traditional sense of the word.
Great Whites Can Travel Great Distances
Great white sharks travel 2,500 miles each year, swimming from the California coast to feeding grounds in the Pacific Ocean.
They can survive the long trip by using reserves of fat stored in their liver as fuel.
Unlike in humans, fatty livers in sharks are a good thing.
Sharks Have Some Pretty Dang Good Eyesight
It used to be a commonly held belief that sharks have poor eyesight. But researchers now know that sharks have very good eyesight — for their environment.
Sharks only have one pigment molecule in their eyes (humans have three), and it can only detect blue-green light. Some researchers believe sharks see in black and white. The jury is still out on that.
They don't really need to see other colors, and as such, their eyes can detect light about 10 times better than humans.
Sharks Don't Have Bones
Weird, right? Sharks are completely boneless creatures. They are known as elasmobranch fish. But you can't just squish a shark like a jellyfish.
Instead of bones, sharks have thick cartilage that acts as a skeleton. The cartilage is lighter than bone — which is good for underwater living — and that cartilage can fossilize with age.
The older sharks get, the more calcium deposits harden their cartilage.
The Biggest Sharks to Ever Live Were 60 Feet Long
The megalodon shark is believed to be the largest shark to ever live, but it hasn't been around for 3.6 million years.
Scientists think these monsters grew between 49 and 59 feet long and bore teeth that could be as long as seven inches. It's believed they fed on whales and seals and had a jaw that was between nine or 11 feet wide.
For perspective, the average door frame is three feet wide. Yikes.
Sharks and Trees Have Something in Common
To tell the age of a tree, you count the rings in its trunk. But what if you want to tell the age of a shark?
Unfortunately, like the tree, you'll have to saw the shark in half ... and then count the rings in its vertebrae, which accumulate as the shark ages.
These "growth bands" can accurately show the age of sharks up to 50 years old.
Only Three Species of Shark Have Double-Digit Human Kills
Of the some 400 species of shark, only a few of them have more than just a few fatal, unprovoked attacks on record.
Those sharks are the great white, tiger and bull sharks:
- Great white sharks have killed 52 people.
- Tiger sharks have killed 34 people.
- Bull sharks have killed 25 people.
This data is from the Florida Museum, which doesn't count provoked attacks. The next deadliest sharks on record are the blue shark and the oceanic whitetip, which have killed four and three people, respectively.
Sharks Are Born With Teeth
If you're wondering how these embryos eat one another, it's not a kind of absorption. Not only are sharks born with teeth, but their teeth develop while they are embryos.
Those shark embryos look pretty gross, too.
The Smallest Shark Fits in the Palm of Your Hand
The smallest shark in the world is known as a dwarf lantern shark. They are reclusive creatures and dwell at depths of over 1,000 feet and can fit in the palm of your hand. They measure around six inches.
Not much is known about them as they have only been observed off the northern tip of South America, and very rarely at that.
Some Sharks Glow in the Dark
Some sharks, like swell sharks and chain catsharks, glow bright green in the dark. That's because of biofluorescence, a phenomenon where an organism absorbs light and reflects it back as a different color.
Other sharks can produce light all on their own. They are known as kitefin and lantern sharks, which live deep in the ocean and have glowing organs called photophores that dot their bellies.
The Biggest Great White Shark Weighs 2.5 Tons
In 2019, divers off the coast of a Hawaiian island snapped photos of a great white shark feasting on the flesh of a dead sperm whale.
This great white shark was massive, believed to weigh in at 2.5 tons (5,000 pounds) and measure 20 feet long.
She's known as Deep Blue and is estimated to be 50 years old. She was first identified in the 1990s.
Sharks Have a Sixth Sense
You probably know that sharks can smell blood in the water, but did you know that sharks can sense electricity? And that, in the water, all living things give off just a tiny bit of it?
All living organisms produce a miniscule amount of energy in water due to differing ion concentration inside the body and the water outside. This produces the tiniest voltage, which sharks can sense, via electroreceptors, from about one-and-a-half meters away.
That means even if a shark's lunch isn't moving, it can detect it if it can get close enough.
Hammerheads Are Shaped That Way Because They're Good at Finding Electricity in the Water
All sharks have electroreceptors (which are located near the eyes, nose and mouth), but the shark that can sense the most electricity in the water is the hammerhead shark.
It's theorized that these curious-looking creatures evolved to have such a wide head because it makes it easier for them to sweep the ocean floor to detect electric fields.
It's like having a scanner with a wider range.
You Can Put a Shark in a Trance by Flipping it Over
You know how dogs will show submission by exposing their bellies? Sharks don't do that. Not just because they submit to no one, but because some sharks go into tonic immobility when they are turned upside down.
Tonic immobility is a trance-like state that is induced when the shark is turned on its back. It's not entirely sure why this occurs, since sharks are apex predators and don't need to play dead for nearly anything.
A Great White Has a Bite of 4,000 PSI
In 2008, a team of Australian scientists used computer imaging to figure out just how much force a big great white shark has in its jaws. They estimated that a 21-footer could produce about 4,000 PSI (pound-force per square inch).
However, size matters. According to Field and Stream, an 11- or 15-foot great white would actually have less PSI force than a crocodile of the same size.
We think that says a lot more about crocodiles than sharks, though.
The Frilled Shark Has the Longest Gestation Period of Any Animal
Humans gestate for about nine months in the womb before they are ready to be birthed. White sharks are thought to gestate for about 12 months (although this hasn't been fully documented). But the frilled shark has a gestation period of up to three-and-a-half years.
That's longer than any other animal on earth. Elephants have a gestation period of up to 660 days, and they are believed to be the mammal with the longest gestation period.
The Rarest Shark in the World Was Discovered in 2019
In 2019, a team of researchers identified a new species of pocket shark (a type of kitefin shark) that was caught in the Gulf of Mexico. The researchers named it the American Pocket Shark, and it is the only pocket shark to be caught in the Gulf.
Pocket sharks are exceedingly rare creatures. "In the history of fisheries science, only two pocket sharks have ever been captured or reported," said researcher Mark Grace of the National Marine Fisheries Service Mississippi Laboratories. "Both are separate species, each from separate oceans. Both are exceedingly rare."
The pocket shark is said to "resemble a mini-whale," according to For the Win. And the only other known pocket shark was caught in 1979, in the Eastern Pacific Ocean.
Shark Skin Is Like Coarse Sandpaper
Shark skin is so rough that furniture makers in the 18th and 19th centuries used shark skin as sandpaper.
Under a microscope, shark skin is made up of dermal denticles, tiny, blade-like teeth.
According to Sharks Info, their skin is so rough that softer animals can be harmed if they happened to get sideswiped by a passing shark.
Tiger Sharks Will Eat Anything
Tiger sharks are non-selective predators that will eat just about anything.
Odd items that have (allegedly) been found in the guts of washed-up or dead tiger sharks include tires, a chicken coop, a fur coat, video camera, a sack of coal, boat cushions, two pounds of copper wire and a Florida license plate (where art thou, Florida man?).
Some Sharks Can Live for a Very, Very Long Time
The oldest shark in the world is believed to have lived for at least 272 years. Researchers say it may have even lived to be 500. If true, that would make it the oldest-living vertebrae known to man.
It was a Greelanland shark, a species of shark that live in the North Atlantic and Arctic waters. They only grow a few centimeters per year but eventually reach lengths of more than 16 feet.
Five Species of Shark Are Warm-Blooded
Most sharks are cold-blooded, but mackerel sharks are warm-blooded. They include the longfin mako, shortfin mako, porbeagle, salmon and white sharks — meaning the great white shark is warm-blooded.
These sharks have the unique ability to generate body heat and retain it even in the cold ocean. White sharks can keep their bellies up to 57 degrees Fahrenheit warmer than the water around them.
Some researchers theorize that the megalodon shark was warm-blooded and couldn't survive when Earth entered an ice age.
The Goblin Shark Has a Jaw Like a Whipped Bear Trap
The goblin shark is one of the weirdest sharks on the planet. These slow-moving, deep-water sharks grow at least 10 to 12 feet long with an unusually long nose.
When a goblin shark wants to eat, it throws its jaws like a bear trap on a short chain. The jaws jump out at a lighting-fast speed of 10 feet per second, so fast that it requires slow motion video to capture.
Goblin sharks can also be bright pink.
Sharks May Have Been Around Longer Than Trees
Trees first appeared 400 million years ago, during the Devonian period. Sharks first may have appeared 450 million years ago, during the Late Ordovician period.
Scientists are still trying to figure out whether the 450-million-year-old ancient scales they discovered were from real sharks or a similar species.
"Shark-like scales from the Late Ordovician have been found, but no teeth," said Emma Bernard of the Natural History Museum in London, England. "If these were from sharks, it would suggest that the earliest forms could have been toothless. Scientists are still debating if these were true sharks or shark-like animals."
These ancient sharks would have looked completely different than the sharks we know today. The first group of sharks to resemble the sharks that we are familiar with came about around 380 million years ago.
Sharks Chew Through a Lot of Teeth
Think you know someone with a toothy grin? They have nothing on sharks, which have an average of five rows of teeth and can have around 3,000 teeth in their mouth.
These teeth are constantly being replaced, allowing these creatures to always have a sharp tooth to rend their prey asunder.
Some sharks can go through 30,000 teeth in their lifetime, and some species have 15 rows of fangs.
Sharks Have Ears
Shark ears have internal ears, which are only visible on the outside as tiny little holes. These ears are only useful for picking up low-frequency noises, from around 10hz to 800hz (humans can hear as low as 20hz and as high as 16,000hz).
Sharks can hear from up to around 800 feet away and can hone in on injured prey.
Some Sharks Can Produce Asexually
Scientists have observed asexual reproduction, aka "virgin birth," in some female sharks. The first time scientists observed this phenomenon was in 2008 with a hammerhead shark, and then a few months later with an Atlantic blacktip shark.
This isn't unique among sharks. There are some 70 vertebrate species like the Komodo dragon which can reproduce without needing to mate.
But asexual reproduction among sharks has a downside. They only produce one pup rather than a full litter. It's still a good way of keeping a shark's bloodline alive, as the mother will pass her genes down to a female pup until one of its lineage can find a mate.
Frill Sharks Are Living Fossils
While sharks have been around for millions of years, many of them have evolved over time. Just how much sharks have changed over time is up for debate, but there's at least one shark that has barely changed since prehistoric times: the frilled shark.
These eel-like creatures have a maw with 300 backwards-facing teeth spread over 25 rows. They're mysterious sharks. Although they're believed to be found in many places, they dwell between 390 and 4,200 feet below the surface, making them extremely elusive.
Shark Mating Looks Violent
Since it's practically impossible to observe sharks mating in the wild, we don't know exactly how the vast majority of shark species reproduce. However, scientists have observed some shark mating rituals, and it involves a lot of biting and maybe even some thrashing.
Male sharks will bite the female for stabilization and for attention. The male latches on to the female and copulates with the female while swimming underneath her or beside her. When it's all done, the females often have visible bite marks. Females that reproduce with multiple partners will have a whole bunch of love bites.
One Kind of Shark Took Out a Nuclear Submarine
The cookiecutter shark is an odd-looking little shark with a round mouth full of sharp teeth. It gets its name from the circular, cookie-cutter-shaped gouges it leaves behind, and it bites everything. People have found the round bite marks in larger fish and mammals (they've attacked great whites and whales), undersea cables and even nuclear submarines.
In the 1970s, these sharks were known to attack the softer areas of nuclear submarines, like its cables and sonar domes. In some cases, these attacks blinded the subs, forcing them to come back to the surface for repairs.
They've even chewed on people!
The World's Fastest Shark Is Really Fast
The shortfin mako shark is considered to be the fastest shark in the world and can reach swim speeds up to 45 miles per hour.
They're big, too. These predators can grow up to 12 feet long and weigh a minimum of 1,200 pounds. They can also leap high out of the water.
One Species of Shark Has Evolved to Look Like Rocks
The wobbegong shark is a peculiar, bottom-dwelling, flat-shaped shark that blends perfectly in with the ocean floor. Their patterns can resemble seaweed-strewn rocks or even coral, and they use this camouflage to wait for prey, striking when it comes near.
No one is quite sure what the Australian Aboriginal word wobbegong word means, but it's believed to mean "shaggy beard," referring to the spindly, beard-like growth around their mouths.
The wobbegong is harmless unless you happen to step on or near one. If that happens, they'll chomp down and not let go.
Some Sharks Can Heat Their Eyes
Some fish and sharks that live in freezing cold waters, like the swordfish, have a specialized organ that can heat up their eyes and brain. But why?
It turns out that warm eyes can see 10 times better than cold eyes, which is extremely beneficial for predatory sharks. This behavior has been documented in swordfish, which have an organ that heats their brain and eye temperatures up to 15 degrees above water temperature.
Mako and porbeagle sharks are known to have this ability as well.
Great White Sharks Look Terrifying Before Attacking
Great white sharks are pretty terrifying in general, but they look like absolute demons before they attack. That's because before tearing their prey into bite-sized chunks, great white sharks roll their eyes back into their head and lower their eyelids. It's a defensive move to protect their vulnerable eyes from damage.
So if you happen to be swimming and see a great white coming toward you and its eyes turn white, well, you better be willing to fight.
Shark Attack? Aim for the Nose
If you happen to be attacked by a shark, punch its nose, attack its eyes or rend its gills with your hands. Those are all sensitive areas that will hopefully dissuade the shark from making a meal out of you.
Of course, shark attacks are exceedingly rare, although not unheard of.
Jaws Was Inspired by a Real Event
In the summer of 1916, about a year before America entered World War I, a great white shark terrorized the coast of New Jersey, killing a total of four people between July 1 and July 12. Sharks were not widely known at the time — when beachgoers at Beach Haven heard the sounds of a person screaming, they thought it was a joke.
The shark attacks made front-page news and caused a shark panic, and a local mayor offered a $100 reward for anyone who could prove they killed a shark. It was the first recorded shark attack in American history and still the bloodiest.
Shark Attacks Are Usually a Case of Mistaken Identity
As a rough estimate, sharks bite anywhere between 50 to 100 people each year (in 2020 there were 57 unprovoked attacks worldwide, down from the average of 84 attacks between 2013 and 2017). The majority of shark bites are not fatal to humans, and some researchers believe it's because sharks don't really want to eat us.
When sharks — namely the great white, tiger and bull sharks — are in full predator mode, they'll attack anything that catches their eye. A flash of a foot in the water or shiny jewelry can attract its attention, leading to a bite. But most of the time, sharks bite, chew and leave.
They'd rather snack on fish.
The U.S. Has the Highest Rate of Shark Attacks
The United States leads the world in unprovoked shark attacks. The country had 33 confirmed cases in 2020 (three were fatal), and 41 cases in 2019, making up over half of the world's unprovoked attacks.
The next country with the highest number of these attacks is Australia, which had 18 attacks, six of which were fatal. Florida alone had 16 shark attacks, making it the most likely place to get attacked by a shark in the world.
But you have a much higher chance of being hit by lightning than being bitten by a shark. Lightning strikes kill about 49 people in the U.S. each year.
Many Important Shark Species Are in Decline
An increase in demand for shark meat and fins, coupled with the long time it takes sharks to reproduce, has led to a declining shark population throughout the world. Rays are also in decline.
However, conservation efforts have led to a rebound in great white and hammerhead species off the U.S. coasts, although hammerheads are still endangered.
So if you see a shark, hug it. Just kidding. Please leave it alone.