- 1 week ago
Why are sharks important to the ocean? Even though we're afraid of these predators, sharks are important to the ecosystem. ? They're really unique: sharks can spit out their stomach! Also, did you know that sharks have good eyesight and have a special eye-warming system! And shark skin feels like sandpaper! Aren't they cool?
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00:01450 million years ago, no, I wasn't around then, the sea level was higher, coral reefs
00:07started to form, the climate on our planet was stable and warm, not even dinosaurs were
00:12around yet, the time when bony and jawed fish we know as sharks appeared.
00:17They've been dominating the oceans and making other marine creatures flee in fear ever since.
00:22Many of them, like great white sharks, have evolved and adjusted to life in the open ocean
00:27as hunters with a pretty high position in the food chain. They're less diverse today than before.
00:33One of the reasons is the asteroid strike from the age of dinosaurs. After it reduced the number
00:38of shark species, only smaller and deep-water kinds that ate primarily fish survived.
00:44They started getting bigger over time. Near the surface, sharks such as makos or great white ones
00:50developed faster movements and are somewhat between gray and blue to blend in with their surroundings.
00:55The epaulet shark can even walk on the land. It can't take a walk on the beach because it can't
01:01breathe outside of the water, but it lives on coral flats in shallow tropical waters, so it can walk in
01:07kind of a crawling motion. But deep down below, there are mysterious, alien-looking, often huge
01:14shark species that didn't come to the surface, which is why they didn't need to adjust to the new
01:20environment and different conditions. They haven't changed a lot through time, so they're some living
01:25fossils. These creatures mostly don't have 5 gill slits, the most common number, but 6 or 7. It's
01:33because there's less oxygen the deeper you go in the ocean, so they need more gill slits. Sharks on the
01:39surface evolved to have fewer gill slits. Six-gill sharks are the most primitive sharks we have today.
01:45Their skeletons are like those of ancient extinct sharks, and they can survive only in very deep
01:51waters. Like cats, sharks have a layer of reflective cells placed inside their eyes, which helps them
01:58see better in the dark, deep sea, or cloudy waters. Sharks on the surface have big eyes because they
02:04evolved to hunt in the sunlight, so they tend to rely on their vision. Those that live in shallow waters
02:10have small eyes, so they can protect themselves from the sand. Like some other deep-sea creatures,
02:16six-gill sharks also have bigger eyes to take in as much light as possible. They have more
02:21light-sensing rods, but don't distinguish colors that well. In the ocean's twilight zone, with the
02:27minimum of sunlight, there's a couple of bioluminescent shark species. They don't take in
02:32light within their eyes, but produce or re-emit it with their bodies. Their skin or organs have
02:38specialized cells that produce a soft blue-green light. Deep-sea creatures that produce their own
02:44light do that to attract their prey, deter animals from going after them, or, scientists think,
02:50communicate with each other. It can even help them to camouflage. They do it by hiding their
02:56silhouettes from animals going after them. They produce enough light to match their surroundings.
03:01The biggest luminous underwater creature is the kite fin shark, found swimming 980 feet below sea
03:09level, preying on groundfish or smaller sharks. It can grow almost 6 feet long and lives 3,200 feet
03:16below sea level. Deep-sea sharks are also bigger than those on the surface. The Greenland shark can
03:23grow up to 24 feet long, bigger than a great white. There's a thing called deep-sea gigantism.
03:29Creatures in nutrient-poor depths of the ocean grow bigger because, that way, they lose less energy
03:35as heat. The Greenland shark lives its life in slow motion. It has a slow metabolism and can go very
03:42long periods without food. With their slow pace, they evolved to live up to 500 years at depths of 7
03:49,200
03:50feet. Sharks in shallow waters catch their prey, relying on agility and speed. But for them,
03:56it's easier because there's plenty of food on the surface. Deep-sea sharks, with less food and slower
04:02life rhythm, had to develop a different style. They're more opportunistic, definitely not picky,
04:08and don't care if their future meal is alive or not. Frilled shark, another living fossil from the
04:15darkest depths, hasn't evolved much through time. And they're one of the last of their kind, with all of
04:21their relatives already gone extinct. It grows up to 7 feet long, primarily hunts on squid, and catches
04:28other sharks and fish. It looks like a dinosaur, a snake-like face, a long, smooth, thin body that moves
04:35in a serpentine way. It can propel itself with the power of its tail and curl like snakes. They don't
04:42swim
04:42in a straight line like other sharks. Cookie-cutter shark grows up to 20 inches. It got the name
04:48because of the way it feeds, biting off small pieces. It's a parasite creature, which means it
04:54feeds off bigger animals but leaves them alive. They have sharp teeth and sometimes even swallow those
05:00that fall off on purpose. Some researchers think it could be because they live in the depths that are
05:06nutrient-poor. If they swallow the teeth, they could recycle calcium and other material from it.
05:12Prickly shark is a rare and unusual creature with many thorn-like denticles and two small dorsal fins.
05:19It lives mostly in the depths of the Pacific region up to 1,900 feet. Ghost sharks are not even
05:26real
05:26sharks, but fish closely related to them and rays. They have big pectoral and pelvic fins, two dorsal fins,
05:34pretty big eyes, and unlike their cousins, have a single external gill opening. Ghost sharks have
05:40slender tails and can grow up to 80 inches, silver to blackish color. They sometimes live in rivers and
05:47coastal waters, but also in the depths of the ocean of 8,200 feet or even deeper. They are pretty
05:54weak
05:55swimmers, so they tend to feed on invertebrates and small fish. Goblin sharks. Swimming through the deep
06:02sea, this creepy shark with a flabby body suddenly sees a small, innocent squid. It goes toward it,
06:09but the potential snack notices it and quickly starts moving to dart away. It seems like the
06:14plan could work at first, but then the shark suddenly thrusts the jaw of its mouth and catches
06:19the poor little squid in a second. After the meal is finished, the animal simply fits the jaw back
06:25into the mouth and goes away as if nothing happened. This is possible because it has a jaw connected to
06:32three-inch-long flaps of skin, which is why it can unfold from the snout. It can grow up to
06:3712 feet
06:38long with a weight of 460 pounds. Scientists think goblin sharks are mostly active in the morning and
06:44evening. The shark has a long, prominent snout and specific sensing organs on it. It uses them to
06:51sense electrical fields in the dark oceanic depths. Seven-gill shark is a big cow shark,
06:57brown to silver-gray on top, white underneath, black and white spots, with a thick body, a small
07:03dorsal fin, and a wide, blunt snout. It can grow up to 10 feet long, mostly lives in the depth
07:09of
07:101,870 feet, but you can also find it in deep channels and bays. It can be aggressive toward humans
07:16if provoked, so don't. Like most deep-sea creatures, it's an opportunistic hunter that's not quite
07:23picky, but likes to go after dolphins, seals, porpoises, and other marine animals.
07:29Mega-mouth sharks mostly live in the depths of 15,000 feet and spend most of their time in the
07:35dark, like me. Scientists discovered it in 1976 because it went near the surface at night to feed
07:42on zooplankton. That's the only time these sharks go there. During the day, they return to their
07:48quiet, dark, and mysterious depths. They are filter feeders, which means they keep their mouths wide
07:54open while swimming, so they filter the planktons they like to eat. There are organs that produce
07:59light inside of their mouths, which attracts potential prey, such as pelagic crustaceans.
08:05These sharks live in the deep parts of the ocean, but you can rarely find them below almost
08:10two miles. Scientists think some other stronger bony fishes out-competed them.
08:16Deep parts of oceans became oxygenated around 70 million years ago, and sharks have been around
08:22way longer. But bony fishes adjusted and adapted efficient ways to use oxygen, while sharks were
08:29slow with adaptations, so they lost. Also, oceanic depths are way colder, which is challenging for fish
08:36and the rest of cold-blooded animals because the speed of their metabolism widely depends upon the
08:42external temperature.
08:44Some sharks have an eerie ability to spit out their stomach and then pull it back into place.
08:49Well, that would be handy. Most sharks eat huge amounts of food, but the problem is they can't digest
08:55everything they've gulped down. So they need a way to get rid of such stuff as sea turtle shells and
09:00beaks,
09:00bird feathers and bones, lobster claws and whatnot. And then, these amazing creatures willingly barf up
09:07their whole stomach, along with all the contents. After the shark is done, it pulls its main digestive
09:12organ back in. And the entire process usually takes no more than a second.
09:17Some shark species, like great whites or mako, have a special eye-warming system. As for the mako shark,
09:24this species often travels vertically across different temperatures. Unlike most people with only one
09:30unmovable jaw, sharks can freely move both their lower and upper jaws. This allows them to get a
09:36better grip on their meal and chew it up faster and more thoroughly. That's comforting.
09:41Sharks give birth to a large number of little ones at once. It depends on the species, of course,
09:47but let's say the blue shark is famous for producing more than 130 pups at a time.
09:53Great white sharks have a more powerful bite than most jungle cats.
09:57A 20-foot-long underwater hunter can produce a force of more than 4,000 pounds per square inch.
10:03And that's a bite four times stronger than that of a lion or tiger. People with their measly 150 to
10:10200 psi bites aren't in the running whatsoever. Swell sharks defend themselves by swallowing huge
10:17amounts of water. Then the shark's body becomes twice its normal size. And this scares potential danger
10:23away. Sharks can grow more than 50,000 teeth during their lifetime. But not all of their teeth are the
10:30same. The strongest and most massive ones are at the front, and those closer to the back are smaller
10:36and not so powerful. But if the front teeth are damaged, these weaker ones can replace them.
10:41It's possible because shark's teeth aren't as deeply rooted as humans and can move.
10:47Shark's skin has the same feel as sandpaper. It's made of teeny, teeth-like scales. They point towards
10:53the animal's tail. This helps to reduce the friction that occurs when sharks move through the water.
10:59Whale sharks have extremely thick skin. In some places on their body, it can be 6 inches thick.
11:05It's one of the toughest in the animal world. Scientists have to make loads of effort if they want to
11:10get
11:10this creature's blood sample. Sharks have an incredible sense of smell. But besides that,
11:16they use one more sense to detect other animals. There are special pores around their head, near the
11:22nostrils, and under the snout. Those are special organs, something like second sight. Every creature
11:28generates a tiny electrical field. Thanks to the pores, sharks can spot these electrical fields and
11:34figure out where other animals are. Sharks are incredibly sharp-eared. They can hear their
11:40potential meal from 3,000 feet away. They can also catch low-frequency sounds, like the ones
11:46produced by a fish's contracting muscle tissue. Sharks have been around for more than 400 million
11:52years. It means they've lived through 4 out of 5 mass extinctions. This makes them way older than
11:58Mount Everest, humans, dinosaurs, and even trees. These creatures go back to the period when coral reefs
12:05were just beginning to form. Some shark species can jump out of the water, like the great
12:10white shark or the basking shark. They're known to leap for more than 8 feet up into the air.
12:16Thanks to this maneuver, they can catch such animals as seals or seabirds. But unless you're in South
12:21Africa, you aren't likely to see sharks jumping out of the water. Shark skeletons are made of muscle and
12:27cartilage, which are lighter and twice less dense than bones. This makes sharks more flexible, which allows
12:34them to make sharp turns when they're chasing other animals. Hammerhead sharks have a weirdly shaped head
12:40for a reason. Thanks to it, these creatures have incredible 360-degree vision. Their eyes are tilted
12:46a bit forward, and it allows them to have an overlapping field of view. The goblin shark's terrifying jaws are
12:54attached to elastic ligaments. They can unfold from the animal's snout for up to 3 inches. It allows the
13:00animal to catapult its mouth forward to catch other marine creatures. Sharks don't sleep as you do. Some
13:07species have to keep swimming all the time. Otherwise, water will stop flowing through their gills, and they
13:13won't be able to breathe. Others do rest, but they don't enter an unconscious state. They just go into special
13:19rest
13:19periods. These creatures don't have eyelids. That's why their eyes remain always open, and their pupils monitor their
13:26surroundings. They also keep their mouth open so that the water can pass through their gills. Sharks can travel
13:32remarkably long distances without needing any rest, all thanks to their bizarre sleeping pattern. For example, great
13:40whites can swim distances of more than 2,000 miles without stopping to eat or rest. How come these creatures
13:47don't
13:47starve? They draw on the fat stored in their livers. By the way, this organ can compose up to a
13:53third of
13:54the animal's body weight. Contrary to popular belief, sharks do not and cannot swim in reverse. Their tails
14:01propel them forward, and their pectoral fins help them to keep their balance in turn. It means that, anatomically,
14:08these animals can't move in any direction other than forward. Sharks have no vocal cords. They can't produce
14:15sounds to communicate with one another or express their emotions. That's why they have to use body
14:20movements, like twisting their bodies or flipping over. Sharks live in all of the world's oceans,
14:26but several species also inhabit freshwater rivers and lakes. For instance, bull sharks have been found
14:32in tropical rivers. They're also known to be able to swim between fresh and salt water. The smallest shark
14:39out there is the dwarf lantern shark. This unique creature doesn't grow longer than 8 inches. But the shark makes
14:46up for
14:46its tiny size in other ways. For example, some of its organs emit light. And since the creature lives in
14:53the shallow
14:54waters, this helps to camouflage it in the rays of sunlight. Blue sharks eat a lot, often more than they
15:01need. Some of this
15:02food can remain undigested for weeks till it's needed for energy. Sharks have something that looks similar
15:08to a tongue. But this organ is called the basial. It's the front section of the cartilage that goes from
15:15the shark's chest to its mouth. It doesn't move and is pretty much useless. The so-called tongue doesn't take
15:21part in the process of feeding. It isn't covered in taste buds. Its only real use might be that it
15:27supports
15:27some of the bones connecting the shark's gills. There are hundreds of shark species in the world,
15:33more precisely, around 500. Some of them are pretty bizarre. Just look at the goblin, basking,
15:39or cookie-cutter shark. All these sharks vary in size, from several inches to dozens of feet long.
15:46They also live in absolutely different environments. Tiger sharks eat whatever they can get their jaws
15:52around. Some of the weirdest things they've munched on are video cameras, bags of money,
15:57license plates from almost any U.S. state, dog leashes, you name it. Each whale shark has a unique
16:04pattern on its skin. These spots and stripes can be used to identify individual sharks, just like
16:10fingerprints are used to identify people. The blunt-nosed six-gill shark can dive to a depth as
16:17great as five Empire State Buildings. Baby sharks are called pups. When they get born or hatch,
16:23they are already fully nourished. And if they choose to swim away from their mama shark,
16:29they don't need to hunt for food for at least several weeks. Uh-oh, did somebody say baby shark?
16:36The hammerhead has an incredible 360-degree vision that's called binocular. This creature's eyes are
16:43tilted forward, and their field of vision overlaps. The wobegong means shaggy beard in an Australian
16:50aboriginal language. And just one look at this underwater inhabitant can explain the name choice.
16:56The viper dogfish knows how to create its own light in the deep ocean, pitch-dark waters.
17:02The animal has needle-like teeth and extendable jaws. This allows it to feed on prey half its size.
17:09Now, at first sight, all these creatures have nothing in common whatsoever. But in reality,
17:14all of them are sharks. There are more than 500 shark species in the world, and lots of them don't
17:20look as if they're related. The most fearsome predators in the ocean, sharks have been around
17:25for more than 400 million years. They have adapted to all kinds of tough conditions. Now, some of them
17:32can live in freshwater, rivers, and lakes. These creatures vary in size, from as small as a human
17:38hand, to 40-foot-long whale sharks. Now, most people would probably feel more comfortable
17:44without sharks lurking in the ocean depths. But few of them know that the disappearance of
17:50sharks would turn into a disaster for our planet. Imagine waking up in the world without these apex
17:57predators. If you're a surfer, you wouldn't have to scan the water for a shark's infamous triangular fin.
18:03If you're a regular beachgoer, you wouldn't have to be on your toes all the time, ready to sprint
18:09toward the shore once you hear a lifeguard's whistle. Movie makers would be confused. They'd
18:14have to set off in search of a new villain. But the truth is, sharks aren't as bad as they're
18:19pictured. Not all of them are large, torpedo-shaped creatures with sharp teeth. For example, the
18:25basking shark has small teeth, and it doesn't even use them for feeding. The horned shark's teeth
18:31are molar-like and help the animal to crush its hard-shell prey. And how can a tiny 8-inch
18:37-long
18:38deep-water dogfish harm you? Unlike what lots of people think, humans aren't sharks' favorite meal.
18:45Usually, we just get mistaken for similar-sized dolphins and seals. Most shark species prefer fish,
18:51squid, and clams. Hey, come to think of it, so do I! Mmm, calamari! Some are filter feeders. It means
18:59they get food by filtering seawater through their gills or mouth.
19:03Anyway, back to the world without sharks. Big shark species are at the top of the ocean food chain.
19:10They hunt smaller fish, for example, tuna. Those, in turn, eat even smaller sea inhabitants,
19:16mostly bottom-feeding species that live off algae. If sharks disappeared, it would totally mess up the
19:22entire food chain. Without sharks to control the fish population, the smallest algae eaters would soon
19:28be swallowed up by predators. No bottom feeders, and algae would grow wild. Along with bacteria,
19:35they would move to coral reefs. Corals wouldn't be able to photosynthesize. Sunlight they used to get
19:41nutrients from the water and carbon dioxide wouldn't reach them. Reefs would fade away,
19:46leaving behind skeletons that would later turn into limestone. It would lead to many marine species
19:52going extinct. Algae would also clog up fish gills and pollute water and seafood. Shark remains are an
19:59important food source for lots of marine inhabitants. For example, orcas, other sharks, and even octopuses.
20:06Without these remains, these species would be at risk of starvation. Or, let's say, tiger sharks.
20:12They live in seagrass meadows and prevent turtles from overgrazing the area. If sharks weren't on the
20:18lookout, all this underwater vegetation would be gone in no time. And that would create a huge problem.
20:25Scientists claim that 50 to 80% of Earth's oxygen is produced in the ocean by plankton. That's algae,
20:32drifting plants, and some kinds of bacteria. Normally, sharks feed on fish that gobble down
20:38ocean-generating plankton. No sharks, and there might be a serious shortage of oxygen in the world.
20:44Little fish would thrive, but only at first. If there were no sharks, injured and sick fish,
20:50their most common prey, would unbalance the schools they live in. This would cause nothing but chaos.
20:56Plus, fish left without control would eat everything they see. Little shrimps, plankton,
21:01and other microorganisms. Soon, all of this would be gone, and fish would eventually starve.
21:08It would affect not only the world's ecosystem, but also the economy. Like it happened once,
21:13in North Carolina. Great white sharks were overfished there, and it allowed the ray population
21:19to grow. It resulted in hundreds of hungry rays eating all the bay scallops. The local fishery had
21:25to close. When there were no more scallops, rays moved on to other shelled sea creatures.
21:31The disappearance of sharks would also harm ecotourism. For example, in the Bahamas,
21:36just one reef shark brings about $250,000 over its lifetime. Divers pay this money to see the
21:44creature in its natural environment. One living whale shark brings Belize $2 million during its
21:50lifetime. Besides, if there were no sharks, we would never know how amazing these creatures are.
21:57See for yourself. Sharks don't have bones. Their skeletons are made of cartilage,
22:03just like some parts of your ears and your nose tip. Cartilage is way lighter than real bones.
22:09Plus, sharks' liver are filled with oils. That's what helps them to be so buoyant.
22:14From afar, sharks' skin may seem to be as smooth as that of dolphins. But in reality,
22:20it resembles sandpaper. It's made up of teeny teeth-like scales. They point toward the tail
22:26and reduce water friction when sharks swim.
22:28Even though sharks don't have bones, their bodies can't fossilize. As these predators age,
22:35they store calcium in their skeletons to make them stronger. That's why million-year-old shark
22:40jaws feel as heavy and solid as bones. Sharks have small black spots near their eyes, nose,
22:48and mouth. They allow these animals to sense electromagnetic fields and temperature changes
22:53in the ocean. Most shark species have an amazing night vision. Even cooler, they can see colors.
23:00They have special reflective tissue at the back of their eyes, which helps them see perfectly with
23:05little light. Now, you might be able to tell a shark's age by counting the rings on its vertebrae.
23:11Each vertebrae has pairs of semi-transparent and non-transparent bands. If a vertebrae has 10 band
23:18pairs, the shark is 10 years old. Such a count is not always correct, but still.
23:25The great white shark's bite is no joke. A 21-foot-long creature can produce a force of
23:31more than 4,000 pounds per one square inch. It means the fish's jaws are four times more powerful
23:37than those of a lion or tiger. And you, with your bite force of 150 to 200 pounds per square
23:44inch,
23:44aren't even in the running. Sharks can heat their eyes thanks to a special retina. It helps them to
23:51have a better resolution of everything they see around and detect their prey. Some bottom-dwelling
23:57shark species, for example, nurse or angel sharks, have a special opening behind their eyes. It supplies
24:04oxygen directly to their brain and eyes. Sharks use this organ when they're resting at the seafloor or
24:10eating. But most shark species have to swim all the time to pump water over their gills.
24:16Sharks live in all oceans on the planet. But several species feel great in freshwater.
24:22Bull sharks, for example, can be found in tropical rivers. They've adapted and can now live in both
24:28fresh and saltwater. And river sharks, true to their name, swim in the rivers of New Guinea,
24:34Australia, and South Asia. The number of teeth may vary from species to species,
24:40but most sharks have more than 15 rows of them in each jaw. One line after another,
24:46they go from the largest and most functional up front to the smaller and less powerful in the back.
24:52A shark can have as many as 35,000 cavity-resistant teeth in a lifetime.
24:57Now, you, as a human, can shift only your lower jaw. But a shark can move both its upper
25:04and lower jaws. It allows the creature to have a better grip while hunting.
25:09Sharks not only smell things exceptionally well, their hearing is excellent too. They can spot their
25:15prey from 3,000 feet away because they hear low-frequency sounds. The predators will easily
25:21recognize the sounds made by a fish's contracting muscle tissue. Sharks are slow-growing species,
25:28and they don't breed often. It makes them extremely vulnerable. People had better protect these
25:33creatures rather than fear them. Oh, and finally, when you go to the casino poker tables,
25:40be wary of one more species, the card shark. If you're not careful, they'll take all your money.
25:46So...
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