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How BIG Were Megalodon Sharks? | Shark Week | Discovery - Video học tiếng Anh
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How BIG Were Megalodon Sharks? | Shark Week | Discovery
How BIG Were Megalodon Sharks? | Shark Week | Discovery
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Legendas (479)
0:03
Oh, wanted again.
0:05
>> Back on. It's back on.
0:07
>> Yeah.
0:07
>> But huge. But huge.
0:09
>> Yeah.
0:09
>> Like a monster.
0:10
>> And knows where to go.
0:12
>> It's not letting go.
0:14
>> Now he wants more.
0:25
>> This photograph is from uncovered Nazi
0:27
files. It's existence only recently
0:30
coming to light.
0:32
The picture was taken just off Cape
0:34
Town.
0:35
>> Yeah, and I bet you Bigfoot was actually
0:37
like driving the submarine, too.
0:40
>> It's absolutely incredible. You take a
0:42
look at that picture and you measure the
0:44
distance from the dorsal fin to the tail
0:46
fin and then compare that to the U-boat
0:48
that's in the foreground. That's your
0:49
scale.
0:50
>> He is really not good at scales.
0:52
>> We're talking about a giant shark. That
0:54
thing is enormous.
0:58
>> Megalodon went extinct 2 to 2 and 1/2
1:00
million years ago. World War II, not 2
1:03
to 2 and 1/2 million years ago.
1:05
>> I guess the implication is that
1:07
Megalodon hated the Nazis.
1:08
>> The other problem is that the narrator
1:11
>> I'm a marine biologist with a focus on
1:13
sharks.
1:14
>> or whatever he is is comparing the size
1:16
of this animal to the U-boat, but
1:18
they're not actually in the same plane.
1:20
Because it's [music] a further back and
1:21
I don't know how much further back that
1:23
is, you can't really make an accurate
1:24
measurement. The chance of this being
1:26
real is none.
1:28
>> Luckily for the Allied forces, it was
1:30
impossible for the Germans to recruit
1:32
Megalodon.
1:34
Unluckily for Megalodon, it died out way
1:37
before even the Trojan War.
1:41
But why?
1:42
>> No one really knows what caused
1:43
Megalodon to go extinct. We know that
1:44
[music] it disappeared off the planet
1:46
around 2 million years ago and we don't
1:49
[music] know much past that.
1:50
>> I always like to tell people that
1:52
there's not one smoking gun. It's
1:54
probably due to a number of different
1:57
[music] causes working together.
1:59
>> So, there are two schools of thought on
2:01
what caused Megalodon [music]
2:02
to go extinct. The first argument is
2:05
temperature change.
2:06
>> Ocean temperatures changed a lot during
2:08
the time that Megalodon was alive.
2:10
Oscillated a little bit between warm and
2:12
then a cool down.
2:14
>> We have the first Antarctic ice sheets
2:16
appear during the late Miocene, and some
2:20
uh scientists believe that a lot of
2:22
these filter-feeding or baleen mysticete
2:24
whales were starting to migrate more
2:27
towards polar regions, [music] and that
2:29
Megalodon just couldn't follow the their
2:32
food sources.
2:36
>> The other one [music] is rise of other
2:39
competitors for their food, such as
2:42
other sharks and larger whales, like
2:44
predatory orca-type whales.
2:46
>> In the middle Miocene, we really have
2:49
the peak diversity of medium-sized
2:52
whales, and we see that that diversity
2:56
sharply decline into the Pliocene time
2:59
period.
3:00
The buffet, as it were, closed down, and
3:04
they just couldn't find the resources
3:06
they needed to survive.
3:09
>> Sounds like Megalodon [music] may have
3:10
gotten too big for its britches.
3:13
But if it hadn't,
3:15
what would it be like on the open ocean
3:17
with Sharkzilla around?
3:19
>> I think it probably would definitely
3:21
impact tourism.
3:25
>> [music]
3:25
>> They probably couldn't come right up to
3:28
the swimming areas just based on their
3:30
size. I don't think that Megalodon would
3:33
be coming in and grabbing people.
3:38
>> [screaming]
3:40
>> If the Megalodons were alive, I mean, I
3:41
know I'm thinking like pool, 100%,
3:44
right? Like I am not getting into the
3:45
ocean.
3:48
>> While the crew dumps gallon after gallon
3:50
of Jaws Juice into the drink.
3:52
I partake in another time-honored Cabo
3:54
tradition,
3:58
the midday siesta.
4:10
Tristan, any sharks?
4:12
>> No, nothing yet.
4:13
>> You just let me know, man. I'm I'm ready
4:15
at a moment's notice. I'm on high alert
4:17
over here.
4:19
>> When you hear that word shark though,
4:20
[music]
4:21
you'll be up.
4:22
>> I'm already up.
4:25
It turns out diving for sharks is a lot
4:27
like fishing. There's plenty of waiting.
4:35
>> SHARK! SHARK! SHARK! SHARK!
4:40
>> WHAT DO WE GOT?
4:41
>> I THINK IT'S A BLUE.
4:45
>> WOW.
4:54
BLUE SHARKS ARE formidable predators and
4:56
have even been observed hunting in
4:58
packs, growing up to 12 ft long and
5:01
weighing in at around 400 lbs. Could the
5:04
blue shark be a dark horse contender for
5:06
the title of Meg killer?
5:09
>> Another pelagic predator, ocean
5:11
wanderer, beautiful animal.
5:16
As you can see, really beautiful blue
5:18
coloration.
5:19
>> It really does. It has like a blue tint.
5:21
>> And then the big pectoral fins, almost
5:23
like a underwater airplane coming in.
5:28
>> Oh my word.
5:31
>> And if you notice, the mouth is set
5:33
slightly further back, so they've got
5:34
this quite big snout.
5:36
It should be called Pinocchio shark,
5:38
really.
5:38
>> With its long nose and recessed jaw, the
5:41
blue shark is best equipped to eat squid
5:43
and small fish. It rarely goes after the
5:46
seals, dolphins, and larger prey that
5:48
the Meg chased.
5:50
>> These blue sharks certainly no
5:51
competition for something like the Meg.
5:53
>> No chance.
5:53
>> No chance.
5:59
Seems like he's kind of taking off.
6:00
>> Because there is other sharks around.
6:02
>> Could be something else in the
6:03
neighborhood.
6:03
>> Yep.
6:04
>> Maybe a good sign that he took off.
6:05
>> Oh, yeah.
6:10
>> [music]
6:13
>> SHARK! SHARK! SHARK! SHARK!
6:15
>> SHARK! SHARK!
6:17
>> ANOTHER ONE.
6:20
IS IT A BLUE?
6:20
>> NO, it's a mako. Look.
6:25
It's got that triangle fin.
6:29
>> WE GOT A MAKO.
6:31
ALL RIGHT, LET'S GET IN THE WATER.
6:32
>> Let's get in.
6:34
>> We race to get our gear on
6:38
and jump in.
6:48
I don't see the mako.
6:52
>> Josh, over there. Two blue sharks.
6:56
>> WOW! OH MY GOSH, THERE'S THREE OF THEM.
7:00
HE'S GOING FOR THE BAIT.
7:02
>> WOW.
7:15
>> TO UNDERSTAND HOW GREAT whites
7:17
strategize when faced with a predator
7:19
over twice their size,
7:22
Tristan and [music] Kenna will observe
7:24
from a drop cage 30 ft below the boat.
7:28
Meanwhile, Soren and Odette will capture
7:30
a bird's-eye view of the action using a
7:32
drone.
7:38
>> They're on top side. They're on top
7:39
side.
7:41
This is giant. We just a few things off
7:43
the bottom.
7:45
>> 10-4.
7:52
>> The shark coming in.
7:57
Oh, COMING UP NOW.
8:01
WE'VE GOT THE COUPLE OF THE SHARKS
8:03
AROUND.
8:07
THE SHARK here for the decoy.
8:13
The CDS down here.
8:16
The shark having a chicken out of the
8:18
trial section.
8:23
And now there's a few of them just
8:25
standing up down here.
8:28
OH, IT'S COMING RIGHT IN NEAR THE TAIL.
8:31
Right in on the tail.
8:33
I thought he's going to have a go.
8:40
Go!
8:43
>> Oh, here it comes again.
8:44
>> Hold it.
8:47
>> Taking the decoy.
8:53
>> Woah, he's not even trying.
8:58
>> He's taking it. He's taking the decoy.
9:01
>> He's got the decoy.
9:07
They all seem interested in the one from
9:09
the side.
9:12
>> Oh, there goes for the tail.
9:16
Going back in where it went before.
9:20
Taking another big bite.
9:23
>> The same great white attacks the tail
9:26
again.
9:28
Even faced with something as massive as
9:30
a leviathan, the goal is to impair
9:33
mobility.
9:39
>> Hey.
9:47
>> Oh, we lost it again.
9:48
>> Oh.
9:49
>> It's back on. It's back on.
9:51
Yeah.
9:51
>> Oh, huge, but huge.
9:53
>> Yes.
9:53
>> Like a monster.
9:54
>> It knows where to go.
9:56
>> He's not letting go.
9:58
>> No, he wants more.
10:05
>> But solving the riddle is Dr. Mike
10:07
Gottfried's dream.
10:09
For years, the paleontologist has been
10:11
tracking fossil sharks here in the
10:13
Chesapeake Bay.
10:16
Suspended in layers of ancient mud that
10:19
formed the Calvert Cliffs are pieces of
10:21
the puzzle.
10:22
Traces of animals that swam or were
10:24
washed out to sea.
10:27
20-ft crocodiles once hunted on this
10:30
shoreline.
10:31
Ancient seabirds soared overhead.
10:35
But this was also a bountiful feeding
10:37
ground for the giant ancestors of
10:39
dolphins, whales, and the predator that
10:42
loomed over this prehistoric ecosystem.
10:46
>> There are a whole range of animals from
10:48
filter-feeding shellfish, fish eating
10:51
the shellfish, small sharks eating the
10:53
fish, medium-sized sharks eating the
10:55
small sharks, big sharks eating the
10:57
medium-sized sharks, and the dolphins,
10:59
and some of the other marine mammals all
11:01
interacting in a food triangle with this
11:04
giant megatooth shark right at the apex,
11:06
right at the top of that triangle.
11:08
>> Though remnants of their prey survive,
11:11
all that's left of these ancient sharks,
11:13
relatives of the mako, the tiger, and
11:16
the great white,
11:17
are their teeth.
11:20
>> The question is, what would be a
11:22
predator on a whale that got up to maybe
11:24
25 [music] or approaching 30 ft long?
11:26
Well, there's an answer to that
11:27
question. The most spectacular predator
11:29
that we know of from the marine
11:30
environment, probably in the history of
11:32
life on Earth, these gigantic sharks,
11:35
gigantic shark called Carcharodon
11:37
Megalodon. [music] And this is just one
11:39
tooth from one of these sharks, just to
11:40
give you an idea of how immense they
11:42
were. And the teeth can get even bigger
11:44
than this. This is a pretty good size
11:45
one, but not as big as they can get.
11:52
This is a shark about the length of a
11:55
Greyhound bus and weighing [music] the
11:56
equivalent of probably seven or eight
11:59
Tyrannosaurus Rex dinosaurs.
12:03
People who think that dinosaurs are the
12:05
biggest, nastiest predators that we've
12:06
had on the planet, uh there was a shark
12:08
that was even bigger, even more
12:10
spectacular, and clearly the most
12:12
astonishing apex super predator that
12:14
that the oceans have known, at least
12:16
since the end of the age of dinosaurs.
12:23
>> SeaWorld in Orlando, Florida, is home to
12:27
one of the world's largest captive shark
12:29
populations.
12:31
Hours before dawn, the staff is rousing
12:34
the residents for their semi-annual
12:36
ritual,
12:37
a physical exam.
12:42
Corraling a reluctant bull shark isn't
12:44
easy,
12:46
but blood tests and ultrasound tell
12:48
researchers about its life cycles.
12:53
This facility has had enormous success
12:56
breeding sharks.
12:58
They want to find out if any are
12:59
pregnant.
13:03
Dr. Gordon Hubbell is a former wild
13:05
animal veterinarian and one of the
13:07
country's most influential fossil shark
13:09
collectors.
13:12
With many shark species on [music] the
13:14
decline, he advocates studying captive
13:16
animals to protect those in the wild.
13:21
Loners by reputation, sharks adapt well
13:24
to aquarium life if mixed with
13:26
compatible species.
13:29
Understanding [music] how sharks feed
13:30
and reproduce and whether they ever rest
13:33
may provide clues to their sketchy past.
13:37
>> We find with shark evolution that
13:39
[music] a shark species exists for at
13:42
least 10 million years or more usually.
13:43
With [music] mammals it's not that way.
13:45
A mammal species will last about a
13:46
million years before it's replaced by
13:48
something more [music] efficient or more
13:50
aggressive.
13:51
So why are we so concerned today? Well,
13:54
we find that with all this perfect
13:56
[music] adaptation that they have, they
13:58
have one flaw. And that is they have a
14:00
very slow reproductive rate. So when a
14:03
population of sharks is decimated,
14:04
[music]
14:05
it doesn't bounce back like the bony
14:07
fish populations do.
14:09
It may take generations. In fact, it may
14:11
never come back.
14:16
>> I think the idea of building an extinct
14:19
shark, a replica of Megalodon, is just
14:22
awesome. Okay, there's been so much talk
14:24
about what this shark could do, what it
14:26
looked like, how it functioned. And
14:29
without actually having a working model
14:30
to scale, those questions can't be
14:33
addressed properly.
14:34
>> Joining Chuck is mechanical designer Jim
14:37
Sherrits.
14:40
Jim is charged with turning scientific
14:42
theory into engineering blueprints that
14:44
will give birth to Sharkzilla.
14:47
>> Pretty cool.
14:48
I'm meeting Chuck here today for a
14:50
mutual reason [music] and I'm hoping he
14:52
can, you know, help me visualize and
14:55
understand a little bit more about these
14:56
creatures so I can build the most
14:58
accurate replica of what Megalodon could
15:00
have been.
15:02
>> But first, Jim and Chuck need to inspect
15:04
the Tooele's whale fossil.
15:07
>> Yeah, he found the first two vertebra,
15:09
you know, which is part of the backbone,
15:11
and then after that I told him, "Okay,
15:12
time to leave."
15:13
>> She kicked me out of the hole.
15:14
>> [laughter]
15:14
>> And then I went in and I started
15:16
excavating all the way down and it just
15:19
kept going and going.
15:20
>> Wow, this is almost all complete, huh?
15:22
>> Right, and you can see all the vertebrae
15:23
just all the way down.
15:24
>> There's even tooth fragments in this,
15:26
too.
15:26
>> Yeah. Yeah.
15:27
>> Also, if you take a look as you go down
15:29
here, yeah, it's too
15:31
we're still in the body vertebrae, the
15:34
thoracic here, I think. And so, this
15:36
[music] thing's probably going down
15:37
another, what do you think, about 10 ft
15:39
or so?
15:39
>> So, it's a good size. So, we're probably
15:41
looking at about, not
15:42
conservatively, 25 ft or more. Yeah.
15:46
Big big whale.
15:48
>> Chuck brings his paleontological
15:49
expertise to our crime scene.
15:52
>> It looks like
15:53
it's been rammed or some kind of injury
15:56
caused the the backbone to actually
15:58
twist at a 90° angle, and then another
16:00
portion of the display at another angle.
16:02
I don't believe that was done by
16:04
currents because I think the rest of the
16:06
skeleton would have been disarticulated.
16:08
And at the end where the head is, the
16:10
head is missing. [music] And yeah, it it
16:12
could be that the head, you know, rotted
16:15
and fell off, but I think it would have
16:16
been found close by. I think that part
16:19
of the injury was, you know, caused by a
16:21
Megalodon.
16:22
>> And I think if we would go through this
16:23
a little bit more in detail, we might
16:25
see some of the scratch marks from where
16:27
it crushed it.
16:28
>> It looks like it's been beheaded.
16:30
>> The head had been bitten off. And that
16:33
was the first point where I thought, you
16:34
know,
16:35
we've got this Megalodon, it probably
16:37
bit the head off of this whale. What
16:39
kind of power does that take? You know,
16:41
what is it that I'm going to have to
16:42
build to represent that?
16:44
>> I mean, that was a huge bite.
16:46
>> The force of that to bite that head off
16:47
would be that would be a big shark. That
16:49
would be a 55-ft shark probably.
16:51
>> Right up my alley. The bigger the
16:53
better. I mean, if we're going to do
16:55
this, let's let's figure out, you know,
16:57
what this thing could have been. Let's
16:59
let's build it. Let's build it.
17:00
>> to see it.
17:02
>> Easier said than done.
17:06
>> Sean, Lisa, come here. We are about to
17:08
solve this Miocene murder. Do you want
17:10
to have the first look at the killer?
17:14
>> Wow, Well, is one big shark.
17:16
>> Was it worth the wait?
17:17
>> It sure was.
17:19
>> What the hell was that?
17:22
>> There were no survivors.
17:28
Now, marine biologist Colin Drake and a
17:30
team of shark experts are in the process
17:33
of planting an underwater camera and
17:35
sonar in hopes of capturing footage of
17:38
the unknown predator that attacked the
17:40
fishing boat.
17:42
>> You see anything down there?
17:44
>> I see nothing. It looks a bit murky.
17:46
>> Mike, come in. Mike. Something's not
17:48
right.
17:49
>> Drake lost visual contact and all audio
17:51
communication with Mike.
17:54
>> Mike, can you hear me down there?
17:57
Mike, come in. Mike.
17:59
Why the hell isn't he answering me?
18:12
I'll be over as soon as possible.
18:13
>> What happened down there, man? You just
18:14
disappeared.
18:15
>> Here you go.
18:16
>> The radio malfunction caused Mike Bonner
18:19
to lose contact with the boat. However,
18:22
the sonar was working properly, which
18:24
means Mike and his scuba partner were
18:26
not alone in the water.
18:31
>> You're all right?
18:32
>> Yeah, I'm all good. I'm good.
18:32
>> You're all right? Okay.
18:34
>> Yeah, I'm all good. Yeah, I'm all good.
18:37
>> All right, how'd you get down?
18:39
You see anything down there?
18:41
>> Was it First of all, the seal just
18:43
disappeared.
18:43
>> Yeah.
18:44
>> And then
18:45
there was a moment there I I turned to
18:46
you and I thought I saw something go
18:48
past you.
18:49
And then something definitely went past.
18:53
>> The guys were in a bit of a cloud there
18:54
for a moment, and unfortunately, they
18:57
couldn't quite make out what was down
18:58
there.
18:59
>> We've managed to place the camera on the
19:01
seafloor precisely where we wanted. This
19:03
is an area where we know [music] that
19:05
submarine has been sighted in the past.
19:07
So, hopefully, we get some good data.
19:31
>> Mhm.
