This Species is Deadlier Than Sharks Love Nature
Transcript
00:00 A great white eats more than a ton of food each year.
00:09 Studies have found that great whites have individual, prey-specific hunting strategies.
00:18 They've learned to attack elephant seals from behind to avoid knife-like claws that can
00:23 leave deep and painful wounds.
00:28 The sharks take a bite, then retreat to let the seal bleed out and avoid a struggle.
00:36 When hunting seals and sea lions, great whites rely on stealth and ambush strategies.
00:42 They stalk prey from hidden depths, then rocket up from below.
00:50 The timing and location of seal attacks is also strategic.
00:55 Sharks usually hunt them around sunrise, when light is low.
01:00 At that time, the silhouette of the seal is easier for sharks to see above, and the dark
01:05 water makes it harder for seals to see sharks below.
01:12 In South Africa, sharks patrol for long periods before sneak-attacking seals sunbathing on
01:18 the rocks.
01:22 Great whites target prey selectively.
01:27 At Guadalupe Island, they ignore the large tuna and jacks that swim in their path.
01:33 They're focused on seals and sea lions, marine mammals that yield more caloric bang for the
01:39 buck.
01:43 When hunting schooling fish, they pick off the weakest, sickest, and slowest prey.
01:49 Not only is this easier for the shark, it also helps prevent the spread of disease and
01:54 strengthens the gene pool of the fish, making sharks evolution's invisible hand.
02:01 They learn from past failed strategies and adjust their techniques accordingly.
02:08 This adaptive behavior is more evidence of their intelligence.
02:18 I think that they are very smart.
02:21 When you come here and when you throw the bait, they never get the bait at the first
02:26 moment.
02:27 They always look around.
02:28 They are very inquisitive.
02:29 They come closer until they are very sure that it's a possible food item.
02:34 It's when they get closer, they get it.
02:36 But also, they are all different.
02:38 They have different personalities.
02:40 Most of them are very cautious.
02:42 They do not come very close easy, but some of them do that.
02:45 One day, we had a female and she took eight baits from one boat.
02:50 And then she came to my boat and she took the bait from my boat.
02:53 So she took nine baits in one day.
02:55 Because she learned that it was easier if she could come from behind and from underneath
02:59 fast.
03:00 And they can get like 40 kilometers per hour.
03:03 So that female in particular was very smart and she took a lot of baits.
03:07 But most of them are very inquisitive and they take their time.
03:13 Just like humans, some sharks are smarter and quicker witted than others.
03:19 They use different hunting strategies based on circumstance and what they've learned works
03:25 best.
03:28 There's no rule book.
03:30 They're very unpredictable animals.
03:32 If you see a school of fish, you see them kind of predictably moving certain directions.
03:37 Sharks are not like that.
03:38 They're unpredictable.
03:39 Because most of them are top predators.
03:42 So that's their nature, to be unpredictable.
03:43 In that way, they're efficient in hunting.
03:49 These unpredictable techniques keep prey on their toes.
03:56 Hidden hunters, like Wobbegon sharks, lie low in wait, often partially buried and camouflaged
04:03 on the ocean floor.
04:06 They won't make a move unless a prey comes very close.
04:14 Bottom hunters, like Nurse sharks, lack the speed and stamina to chase prey.
04:20 Instead, they cruise above the bottom in search of resting crustaceans.
04:31 Filter feeders, like whale sharks, target plankton and small fish.
04:38 Giant gulps at the surface draw water into the mouth, suctioning in plankton.
04:45 Pads that cover the entrance of the throat filter the plankton.
04:50 A single shark can filter more than 160,000 gallons of water per hour.
04:56 In just four hours, it can filter enough water to fill an Olympic-sized swimming pool.
05:08 At Costa Rica's Cocos Island, white tip reef sharks prefer to hunt in packs and at
05:15 night, poking their heads into crevices on the reef to flush out resting fish.
05:24 And hunting strategies have made sharks the most successful predators in the ocean, but
05:29 not the most successful on the planet.
05:35 One-third of all sharks are threatened by overfishing.
05:45 For every human killed by a shark, humans kill two million sharks.
05:53 As a result, about 100 million sharks are killed each year.
05:58 That's 11,000 sharks per hour.
06:03 Most are killed for their fins, used in shark fin soup, or as bycatch in nets, meant to
06:10 snare other marine life.
06:16 Great white sharks take between nine and 16 years to reach maturity.
06:21 Adults give birth to just two to ten pups every two or three years.
06:28 This slow climb to maturity makes white sharks vulnerable to even moderate levels of fishing.
06:38 Sharks simply can't replenish themselves at the rate they're being fished and killed.
06:46 Net loss also poses danger for sharks, as nets are cast to protect swimmers and surfers
06:52 at beaches.
06:54 We don't fully understand what is going to happen to the oceans when you remove these
06:58 top predators.
06:59 And I think by the time that it's fully understood, it's going to be because it's reached that
07:04 tipping point, and then it might be a matter of looking back and saying, "Oh, we've overfished
07:08 them.
07:09 We've killed too many in nets or drum lines or from shark finning and things like that."
07:16 In spite of the destruction caused by some humans, others work to discover just how smart
07:22 these predators are, to demonstrate that they're worth saving.
07:29 The evidence they've uncovered reveals that sharks are intelligent and operate at a much
07:35 higher and more nuanced level than we believed.
07:40 They're not mindless eating machines, ruthlessly pursuing their next meal by instinct alone.
07:48 To outwit their prey, they must operate on an intellectual level, higher than ordinary
07:54 fish.
07:59 They're efficient hunters with an innate curiosity that's been mistaken for savagery.
08:04 A lot of TV shows make sharks out to be particularly voracious and malicious.
08:10 And actually, I would argue that they have no maliciousness.
08:16 They're a predator just like anything else, like a lion or a bear.
08:21 And I think the thing that really terrifies people about sharks is, for the most part,
08:25 a lot of those terrestrial predators we've exterminated.
08:29 So you might be able to see a lion in a game park in Africa, and cougars might be around
08:37 in the mountains.
08:38 But for the most part, we've eliminated the influence of these, you know, large, scary
08:44 things with big teeth in our day-to-day lives.
08:47 And the thing that we haven't really done that to yet is sharks.
08:54 Sharks engage in elaborate social behaviors, have distinct personalities, and create social
09:03 networks.
09:06 They're pillars of evolution that have existed 100 times longer than humans.
09:14 Yet their true nature is only just being revealed.
09:21 Ongoing exploration promises even greater discoveries, as scientists aspire to once
09:27 and for all solve this undersea mystery.
09:33 How smart are sharks?
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