How many sharks are there in the world

Lastly, sharks that hunt fast-moving prey like fish and squids have bigger eyes and presumably better eyesight than those that eat non-moving prey.

In addition, some species have a clear membrane the nictitating membrane , which slides down to protect the eye in dicey situations. Taste buds that line the mouth and throat allow them to taste their food before they make the commitment to swallow. This helps them avoid dangerous prey items, which might have a bad taste.

Instead they have a small piece of cartilage on the floor of their mouth called a basihyal that lacks taste buds. But the cookie-cutter shark Isistius brasiliensis uses its basihyal to rip small chunks of flesh from fish and other animals. Sharks have truly remarkable noses. As they swim, water passes into their nostrils and across sensory cells lining the skin inside. These sensory cells are able to detect relatively small amounts of a chemical signal in the water.

Just like we can tell where a sound is coming from depending on which ear the sound waves hit first, sharks can tell where a smell is coming from depending on which nostril the smell hits first.

Now those are some impressive nostrils! Sharks have two small openings on their head behind and above their eyes that lead to internal ears. There, sensitive cells allow sharks to hear low-frequency sounds and to pick up on possible prey swimming and splashing in their range. Instead, like other fish, a shark has a lateral line running along the middle of its body from head to tail. A fish swimming nearby displaces water as it goes along, creating ripples; when those ripples hit the lateral line system, the shark can detect both the direction and amount of movement made by prey, even from as far as feet meters away.

Because of this ability, they can sense prey in total darkness. Sharks detect the electrical fields through small pores on their head that are full of special cells called ampullae of Lorenzini.

These cells are filled with a jelly-substance that conduct electric charges received from ions, like sodium and chlorine, which are found in salt water. When a fish moves its muscle to swim, the shark can feel it; when one is wounded and flopping around, it sends out a large electrical signal that will attract the shark. Sharks also use electroreception to navigate. They can also sense objects in the water, allowing them to create a map of their immediate environment.

With over species of sharks, there are many different shark sizes and shapes. The largest shark and also largest fish is the gentle whale shark Rhincodon typus , which can reach lengths of 39 feet 12 meters. The smallest is the dwarf lantern shark Etmopterus perryi clocking in at only 8 inches long.

This tiny shark is found in deep waters off the coasts of Colombia and Venezuela. In between there are hundreds of large and small sharks with various shapes and with a multitude of important ecological roles in the ocean.

The first sharks evolved more than million years ago, long before dinosaurs roamed the Earth. Instead, fossilized shark teeth along with limited shark skin scales called denticles , vertebrae, and a few impressions of ancient shark tissue give us clues to what happened to sharks over time. The oldest confirmed shark scales were found in Siberia from a shark that lived million years ago during the Silurian Period, and the oldest teeth found are from the Devonian Period, some million years ago.

Based on these fossils, more than 2, species of fossil sharks have been described. Because sharks shed so many teeth during their lifetimes, there are many shark teeth out there. In the middle ages fossilized sharks teeth were thought to be petrified dragon tongues and shark teeth have also been used throughout history to make weapons. But once you find a shark tooth, what can it tell you about the shark itself? Some scientists compare the shapes of ancient shark teeth to those found on modern sharks to look for similarities suggesting that they are related species.

This method doesn't always work, however, making it very difficult to figure out how ancient fossilized sharks are related to modern ones. Not much is known about the earliest sharks. It's impossible to tell what the earliest known shark named Elegestolepis looked like based only on scales left behind million years ago, much less the million year old shark named Leonodus identified by a two-pronged tooth. They likely were small coastal or freshwater fishes. We do know that they inhabited a very different world than the one we know.

The shape of the land even looked different million years ago: there were just two continents, Laurasia and Gondwanaland, surrounded by a warm shallow sea. The fossil record tells us that by million years ago, ancient sharks would have been recognizably related to the sharks we know today. There were many other ancient shark species found in both fresh and salt water that evolved over millions of years and survived four mass extinction events.

After each mass extinction, many shark species died, but the ones that survived went on to live and evolve further until the next mass extinction. During the Carboniferous Period to million years ago , shark diversity flourished. For this reason, it's sometimes called the Golden Age of Sharks. By the end of the period, 45 families of sharks swam in the seas—and resulted in some strange-looking animals.

Males of the extinct species Falcatus falcatus were six-inches long, and each had a strange sword-like appendage growing off of its head. One fossil preserved a pair of these sharks in the act of mating, with the larger female grabbing the male by its head spine.

Another strange head appendage has been found on the extinct Stethacanthus , a two-foot shark with an anvil-shaped dorsal fin. And who could forget Helicoprion , an ancient shark that had a whorl of teeth in its mouth like a buzzsaw. But all good things must come to an end: million years ago the largest extinction event in Earth's history called the Permian-Triassic extinction event wiped out 95 percent of all living species on the planet, including many of these bizarre sharks.

Only a few families of fish—food for large ocean predators like sharks—survived the Permian extinction. But as the seas recovered, so did they. Ray-finned fish began to fill the seas, adapting to different habitats.

And with them, their predators evolved too. During the Jurassic to million years ago and Cretaceous to 66 million years ago Periods, marine reptiles like ichthyosaurs, mosasaurs and plesiosaurs ruled the seas—along with some sharks. By the mid-Cretaceous, around million years ago, sharks that resemble large, fast-swimming modern sharks started to appear. In , the fossilized remains of the foot meter shark Ptychodus mortoni , which swam the ocean 89 million years ago, were found in Kansas Kansas at that time lay under a vast inland sea.

Only a jaw was found—a very big jaw—lined with hundreds of flat teeth that would have helped it crush shellfish. Thus, despite its size, it was likely a slow-moving, bottom-dwelling shark. Around the same time lived the Ginsu Shark Cretoxyrhina mantelli —a slightly smaller shark, at 20 feet 6 meters long, but much more fearsome. The Ginsu is one of the better-known ancient sharks because paleontologists found a nearly complete fossilized spine for the species, along with very impressive teeth.

They were very sharp, 6 centimeters long, and likely used to kill and eat larger fish prey. Ginsu teeth have been found embedded in pleisiosaur and mosasaur bones, suggesting that they may have gone after small marine reptiles as well. Another group of sharks known as the crow sharks Squalicorax were smaller, at around one-third the size of the Ginsu. Instead of ruling as fierce predators, crow sharks were likely scavengers that fed upon already-dead animals.

Paleontologists think this because bones of large animals from this period have been found covered with crow shark bite marks. The Cretaceous—Paleogene extinction 65 million years ago wiped out the dinosaurs—but not the sharks. Approximately 80 percent of the shark, ray and skate families survived this extinction event. Some of those that survived are the ancestors of the sharks alive today.

In the 65 million years since the Cretaceous-Paleogene extinction, sharks have continued to evolve and become the diverse group of cartilaginous fishes we see today. Some modern sharks have direct ancestors from before the Cretaceous extinction event. Cow sharks date back to million years ago, while the snake-like frilled sharks have fossils from 95 million years ago. That doesn't mean that these modern animals are identical to their ancient versions; on the contrary, they have certainly undergone evolution and changed over the millions of years of their existence.

But paleontologists are fairly certain that our modern sharks are directly related to extinct relatives known to us by fossils. The lamnoid sharks order Lamniformes —including the great white, mako and thresher sharks, among others—also can trace their lineage into the Cretaceous. But paleontologists don't have a good sense of which ancient sharks species evolved into modern lamnoid sharks. Their ancient ancestors left behind many fossilized teeth, but there isn't an easy way to put them in order without more information provided by fossilized skeletons.

One well-known extinct relative of modern lamnoid sharks is the Megalodon Carcharodon megalodon , which was more than 50 feet long with seven-inch teeth and lived 16 million years ago. It went extinct 1. For many years, some scientists believed that the Megalodon was an ancestor of the great white shark—but great whites are more closely related to ancestors of modern mako sharks.

It is likely that the Megalodon and great white sharks even coexisted, with the Megalodon feeding primarily on whales and the great white on seals.

One notable feature of sharks is that large filter feeders evolved separately multiple times. Between 65 and 35 million years ago, several sharks evolved away from predation and towards filtering tiny plankton out of the water for sustenance.

An ancestor of the modern-day carpet sharks evolved into the whale sharks Rhincodon typus we see today, while two ancient ancestors of the mackerel sharks evolved into basking sharks Cetorhinus maximus and megamouth sharks Megachasma pelagios.

The shark family that evolved most recently is that of hammerhead sharks Sphyrnidae , which first appeared 50 to 35 million years ago. Sharks are found in waters throughout the world, from shallow water to the deepest parts of the ocean. Some species migrate vast distances, moving between various locations to breed and find the best sources of food. Some of these migrations are fairly easy to track. This was the focus of our most recent study, conducted with colleagues based in the South Pacific archipelago of New Caledonia, France, Australia and the U.

The results were very exciting: 22 water samples collected over a few weeks detected more sharks than hundreds of baited underwater camera observations over two years, and thousands of scuba dives over a period of decades.

Nearly half of the species detected through environmental DNA could not be found at all using traditional methods. And while eDNA could detect the presence of some sharks in about 90 percent of the samples, underwater cameras could only manage just over 50 percent, and scuba diving around 15 percent. Interestingly, eDNA outperformed the other methods in both pristine and impacted areas.

A range of shark species were detected even in busy, noisy and depleted areas, where they were thought to be extirpated. Similarly, eDNA can help by revealing the appearance of newly established, alien species that are expanding their range. All of this is good news for everyone, and this is why. Maybe some time in the future, someone will invent a special machine that locates, identifies and counts all the creatures in all the oceans! There are many, many different types of sharks, including Great Whites, in the oceans of the world.

Because there are so many different sharks in so many different bodies of water, it would be impossible to count them all. Can you believe there could be a billion or more sharks in all the oceans around the world? That's a LOT of sharks! Mac's Class! We're super glad you learned some new things about sharks today!

You taught US something, too! We learned that there is a show called Dolphins of Shark Bay! It's about a group of dolphins who live in a bay where a LOT of sharks live and eat! Thanks so much for sharing your shark story, Nmb!

Hi, Kadoodle! There are many reasons why people kill sharks, but one of the main reasons is to eat them. In many parts of the world, people eat sharks. Some cultures even use parts of a shark's body as a type of medicine. We're glad you visited Wonderopolis today and asked such a great question!

That's a good question, Andrew! We are undergoing some spring clearing site maintenance and need to temporarily disable the commenting feature. Thanks for your patience. Drag a word to its definition. You have answered 0 of 3 questions correctly and your score is:. Want to add a little wonder to your website? Help spread the wonder of families learning together.

We sent you SMS, for complete subscription please reply. Follow Twitter Instagram Facebook. How many sharks are in the ocean? How many different species of sharks are there? What is the largest shark? Wonder What's Next? Try It Out Are you ready to learn more about sharks? Check out the following activities with a friend or family member: Check out the Monterey Bay Aquarium's Open Sea Webcam for a sneak peek at some sharks.

How many sharks do you see? Can you identify what type they are? Would you like to swim with sharks? Why or why not? Have you ever watched Shark Week programs on Discovery? If you had a pool big enough to hold one, would you want a shark as a pet? Did you get it? Test your knowledge. What are you wondering? Wonder Words species infinity mariners cartilage connective tissue commercial recreational responsible reduced populations count bones strong softer accurate specific impossible Take the Wonder Word Challenge.

Join the Discussion. Sara Apr 1, Apr 16, That's a great question for a Wonder Journey, Sara. Let us know what you learn! Mikayla Pierce Jan 8, Do we know how many sharks we still have. Jan 8, Jan 15, That's a great question for a Wonder Journey. Turner Nov 13, Nov 13, Hi Turner! Thomas Nov 8, Nov 10, Hi, Thomas! You'll have to take a Wonder Journey to find that answer.

Finnuth Sep 1, Sep 3, Nick May 31, I have nothing against Sharks, but why play favoritism? Why is everyone concerned about Sharks and not other fishes it sea life like sea-horse, octupus. You know there are billion Sharks but not necessarily billion crabs, octupus, salmon etc They may also go extinct. I love sharks all sharks and how can you not pick. Dec 12, Liesje Jul 10, Jul 11, And fish. Also friends, not food. Jun 4, Plus, sharks are scary.

Pipper Apr 21, Apr 22, More than one? Rishita Aditya Mar 21, Alexa Dec 19, What is the different shark species in the world. Dec 19, Brenden Dec 17, Timothy cox Sep 21, Allyson May 15, Are sharks afraid of humans? If so why? My favorite type of shark is a great white shark because they are really cool.

Feb 6, Thanks for sharing your thoughts, bea s! Oct 8, Robert Nov 5, I think people like sea food with sharks in them probe. May 25, Kaileah May 15, May 21, May 24, May 14, Shane May 9, Charles May 7, Do sharks have lungs or gills? They come up for air but in the water they don't blow bubbles or anything they are normal as if they have gills. May 9, Charles May 9, We're happy to help!

Hi, sarai! Sharks do sometimes eat trash that is found in the oceans. HI my name is Michael and I think that Wonderopolis is the best website to learn something. Hi, Michael! MartinAV24 Jan 18, I thought sharks were scary and horrible, but no there really just protect them selfs. Why do they call them sea dogs? Jan 22, Camposks24 Jan 18, I wonder how scientist find out about all these types of sharks?

Jan 25, Becky Jan 18, I would recommend to answer your title question whickph is how many sharks are still leaving in the world, but in addition I liked the information you said. Thanks, Becky!

Anne Jan 5, I enjoyed reading the facts about sharks and it definitely worrys me that million sharks are killed each year but I also think it is important that we recognise that sharks and not primarily killed for food but rather are killed after being caught in nets for fish intended to be eaten - for every pound of intended fish caught 5 pounds of unintended fish are caught including dolphins, whales and sharks. With between billion sharks being bi-kill each year - however I still appreciate the work you are doing to inform people about this topic.

Jan 9, Alexandria Jan 4, Peter Oct 24, Oct 26, Aug 31, Tanner May 17, May 18, Dory Aug 29, Hi i'm dory and i have short term memory loss that is why they did a movie. Hi, Dory! Have you met the shark Bruce?? Josh Aug 18, Aug 20, The world is a pretty wonderful place, Josh!! Gavin Apr 11, Apr 12, Vivian Jan 4, I did not know that fisherman are the ones who are killing the sharks!

But how? Jan 4, Dec 16, Karter Sep 12, This is cool I wish I knew about this when shark week was here! But it is cool to learn about sharks!!!!! Sep 13, We're glad you found this Wonder about sharks, Karter! Tianna Apr 8, This is believed to be the most dangerous type of shark in the world.

People have been able to see them as they are among the rare species that do raise their heads out of the water. Great white sharks can grow up to 16 feet and weight around 1,, pounds. More people have been attacked by great white sharks than any other shark species. Locations where they are living have been identified and people are encouraged to stay away from them. Even so, swimmers, surfers, and divers have had numerous encounters with them.

While all sharks have similarities including they way their bodies are formed they also have many differences. Now that you are aware of some of the different types of sharks out there you can look into those that capture your attention in more detail. Sharks are very interesting and you will find there is an abundance of information out there to explore.

Types of Sharks. Leopard shark.