Prática de Shadowing: The Insane Biology of: The Narwhal - Aprenda a falar inglês com vídeo
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For centuries, humans have been entranced by the mystical powers and ethereal beauty of a mysterious, spiraling horn.
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A horn that was thought to possess magical qualities, from purifying water to counteracting poisons and deadly diseases if ingested.
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Its powers were so sought after that Queen Elizabeth paid 10,000 pounds for a horn in the 1500s.
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6.3 million pounds in today's money.
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But Queen Elizabeth and all the other purveyors of this magic horn got certifiably bamboozled.
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The horn they so coveted was a real thing, and it probably inspired the unicorn legends.
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But the actual creature is not quite so ethereal.
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Maybe you're thinking, that's still a majestic creature even if it's not a unicorn.
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Yeah, maybe you would think that, until you learn that that spiraling horn is actually a tooth.
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extremely long, weird buck tooth.
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The narwhal somehow gets away with this, but any other animal with a single, three meter long tooth would be immediately cancelled.
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And things don't get better when you learn the name narwhal comes from Old Norse meaning corpse whale, because the color of their skin resembles a drowned sailor.
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Gross.
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And honestly, they just keep getting weirder the more you learn.
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Scientists attached satellite trackers and cameras to narwhals and observed them spending the majority of their hunting time swimming upside down.
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In rare cases, belugas and narwhals have even mated to create the hybrid narluga.
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Narwhals are also one of the few cetacean species that polar bears will actively hunt, rather than waiting for a dead carcass to wash ashore,
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which means they have to be especially careful about where and when they come up to breathe.
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But even despite this, they have an incredible lifespan, with estimates that they can live up to 100 years,
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because narwhals are not just weird, but also incredibly hardcore.
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Narwhals are one of the deepest divers, swimming as far as 1,800 meters underwater to hunt for food, and going especially deep in the winter.
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They manage 18 to 25 dives per day thanks to their thick blubber that provides insulation and energy, collapsible ribs that bend under high pressures,
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and an incredible ability to store 70 liters of oxygen in their lungs, blood, and muscles.
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Their bodies don't have the fast-twitch skeletal muscles that give dolphins such propulsive speeds,
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and instead have muscles better able to handle endurance swimming, requiring less oxygen.
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But the biggest question about them is, what's the deal with that horn?
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Or rather, that big ol' tooth?
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It's certainly fun to try to guess.
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Multitool?
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Intergalactic antenna?
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Supersonic speed?
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Kebabs?
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Predator evasion?
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A meter of its lies?
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But jokes aside, scientists still don't really know the real answer.
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Some past theories about its purpose included sound transmission, thermal regulation, breaking ice, and even a breathing organ.
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But since it's usually only males who grow the horn, it can't be critical for survival.
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And yet some females do also have the horn too, so it also likely isn't just to be for mating.
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So what the heck is going on here?
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What on earth are these long protruding teeth horns for?
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Narwhals belong to the Odontoceti, or toothed whale order.
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Like their distant relatives, the sperm whale and the orca, narwhals are endowed with teeth, but only two of them.
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And in their case, the teeth are actually known as tusks.
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Female narwhals have two tusks embedded in their jaw, which rarely become visible.
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In about 1.5% of females, one of those tusks will grow into a huge spear, just like the males.
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And in some cases, males will have no tusk, though sometimes they'll also grow two, for for reasons we don't really understand.
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Even though the horns are called tusks, they have a very similar anatomy to other mammalian teeth.
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The outer layers of the tusk are hard material to protect the nerve at the interior.
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The outermost layer is cementum, a calcified material to protect the tooth.
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Immediately beneath it is the dentin, which is more bone-like and immediately surrounds the pulp tissue.
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What's unusual about narwhals is that they have no enamel covering to protect their tusk,
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and the cementum and dentin actually have fluid-filled channels called dentinal tubules
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that interact with the environment and pass messages onto the nerve, which goes directly to the brain.
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All mammalian teeth have these channels, but they're generally covered by enamel.
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Otherwise the tooth becomes hypersensitive to stimuli and painful.
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Think about what happens when you bite directly into a popsicle.
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I can't even watch people bite into an ice cream without cringing.
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Many people are like me and experience discomfort in their teeth, because our teeth are sensitive to the sudden temperature change.
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And that's with a coating of enamel protecting our dentinal tubules.
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Yet narwhals have a 2 to 3 meter projecting tooth without any enamel, which is nearly always immersed in arctic ice-cold water.
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We don't know for sure that they get toothaches, but it certainly seems uncomfortable to have a fully innervated and sensitive tooth constantly exposed to icy water.
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But maybe there's a good reason for such a sensitive tooth.
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So researchers devised a fascinating test to see what it might be useful for.
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They decided to measure how well a tusk can detect changes in water salinity.
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This is potentially a very important adaptation
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because one of the risks of living in the Arctic is getting stuck in what's called an entrapment.
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Narwhals breathe air like all mammals, but they live in an environment that's absolutely covered in ice.
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Of the 25,000 square kilometer waterways they traverse, there's often less than 3% open water,
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and sometimes as little as half a percent of open water, and they absolutely can't break through the ice with their tusks.
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And if the weather changes suddenly, with a burst of cold and wind, ice can form incredibly rapidly,
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closing off the areas that narwhals need to surface to breathe.
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The whales can become stranded without enough breathing holes, and hundreds will squeeze into shrinking openings in the solid ice.
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Many unfortunately die if they can't get to the small ice gap in time.
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And the ones that do manage to battle for space to breathe become easy prey for polar bears
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that gather around the breathing holes.
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Between 2008 and 2010 alone, locals reported four entrapments of large groups of narwhals up to 600 individuals,
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due to the sudden growth of sea ice.
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So how does salinity factor into the dangers of entrapment?
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Because the ice contains very little salt, only the water freezes.
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So the water around newly formed ice becomes much saltier than it is in other locations.
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That means being able to sense a sudden increase in salinity would be very helpful for narwhals, because they'd know it was time to book it and avoid getting trapped in the ice.
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Now back to the study.
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Researchers captured six male narwhals and hooked them up to electrodes to detect their heart rate,
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then made a jacket for the tusk so that they could fill it with fresh water and then a high salt solution.
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The researchers found that narwhals' heart rate fell with fresh water and rose dramatically with saltwater,
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probably because the narwhals were panicking about being trapped in ice, though that's not something we can ask them directly.
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What the test did confirm for researchers is that the tusks have sensory capabilities, and that if the tusk is damaged, as was the case for two of the males,
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they have a harder time detecting salinity changes.
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And we know narwhals travel in pods, sometimes with hundreds of members, so maybe those who don't have a tusk are just taking signals from the ones that do.
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But that doesn't explain what happens with an all-female pod when none of them have tusks.
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So it seems like the tusk can't just be for this.
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There's got to be more going on with this protruding tooth horn.
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Despite the fact that narwhals only have two teeth, and neither are adapted for chewing, They actually eat fairly sizable fish,
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including halibut, cod, and gonadus squid.
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They find their prey using echolocation, then swallow them whole using a strategy called suction feeding.
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Basically they create a vacuum in their mouth by retracting the tongue and just slurp up the fish.
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Although narwhals are very hard to follow in the wild, we've learned a good amount about their diet thanks to their long history of being hunted.
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Scientists have studied preserved remnants of their stomach, as well as stable isotopes of carbon
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and nitrogen in their skin to understand what they're eating and how deep they're going to get it.
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In the past, researchers thought narwhals were picky eaters
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and would therefore be more likely to suffer from the combined effects of climate change and overfishing.
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But a recent study compared the world's three main narwhal populations from the Baffin Bay, the Northern Hudson Bay, and East Greenland.
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The scientists were surprised to discover that their diets were quite varied from one place to another.
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In East Greenland, the narwhals seemed to feed more in a pelagic food web, especially on capelin fish.
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The North Hudson Bay narwhals did the most benthic feeding, partly explained by the fact that they live in shallower water.
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They largely ate benthic shrimp.
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The Baffin Bay narwhals had the highest levels of nitrogen-15 isotopes, which means they feed at the highest trophic level of the three groups,
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including a lot of halibut.
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But possibly the most interesting of all was the differences between male and female diets.
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Males are significantly larger than females, and it seems that they make more frequent and deeper dives, so they can feed on benthic species more easily.
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It's possible that their greater size allows them to hold more oxygen for these dives.
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And then there's the presence of the tusk.
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Using it to stab prey, kebab style, seems like a bad idea, because the narwhals then wouldn't have any way of getting it off their tusk.
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But in 2017, scientists captured footage of narwhals using their tusk to smack fish, which seemed to momentarily stun them immobile.
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And from there, the narwhals could more easily hoover up the fish.
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This behavior has only been seen once, so it's impossible to say if it's a widespread practice.
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We also don't know if it makes males better hunters than females, but that certainly doesn't seem to be the case.
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So it seems like there still must be something more to this tooth horn.
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We've seen that narwhal tusks are sensitive to the environment around them, and useful for bopping fish on the head.
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But are these the real purposes of narwhal tusks, or just a nice side benefit?
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When a specific trait appears in the males and not the females of a species, scientists look at a couple of clues to try to figure out whether
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that trait is the result of sexual selection or not.
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One of the first things to examine is fitness.
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Not in the Jimbro way, but in the context of being able to survive the environment.
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In other words, are female narwhals without a tusk capable of thriving in the Arctic?
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The answer is yes, which suggests the tusk is not a crucial element of survival.
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So is this horn perhaps something more to do with mating, or sexual selection?
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To understand this, it's important to consider hyperolometry, which is common in sexually selected traits.
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It means that for the organism's body size, the sexually selected traits are larger than would be expected.
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Take the claw of a fiddler crab, for example, an important tool for aggressive posturing and for attracting mates.
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As a male crab's body gets larger, the claw doesn't grow in size with it in a 1 to 1 ratio.
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It grows even more.
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This steep line has a slope of 1.56, meaning the relationship between these beefy claws and body size is hyperallometric.
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And hyperallometry is common in sexually selected traits, because more exaggerated traits can more easily signal your genetic quality to your mates,
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even from a distance.
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So do narwhal horns fall into this category?
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To test the hypothesis that narwhal tusks are sexually selected,
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researchers compared the body and tusk size of 245 adult male narwhals collected from 1983 to 2018.
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Sure enough, they found the relationship between tusk length and body length to be hyperallometric.
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And another study found that a larger tusk size correlated to a larger pair of testes.
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And the tusk keeps growing for the entirety of the narwhal's life, so that thing is getting longer and longer the older they get.
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The real question about the narwhal is whether the visual of a big tusk alone is enough to attract a female, or if the males have some kind of dominance display as well.
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Researchers have found that 40-60% of narwhal males have damaged or broken tusks, and many of them have scarring on their heads,
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and even bits of tusk embedded in their jaw.
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The tusks can't withstand direct ramming forces, but they are resilient enough for lateral strikes.
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This might explain why we sometimes see narwhal males crossing their tusks above the water.
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Maybe they're doing some kind of jousting performance for the females.
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We just don't know, because their breeding period tends to be in March and April, when they're still living in the dense ice of winter.
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You might also be wondering, if these tusks are solely for the purpose of finding a mate,
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how come narwhals also have the ability to stun fish and sense how salty the ocean is?
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There is a couple of theories about that too.
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Maybe those traits have been retained from the evolutionary ancestor of narwhals.
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Maybe the tusks were used solely for sensory purposes until some
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of the females started selecting males for the size of the tusk.
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On the other hand, the tusk might be currently evolving into a sense organ.
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Maybe its extra abilities are nice little add-ons.
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We do know that crustacean claws aren't just about getting a mate, but can also be used as weapons, for hunting prey, and for chemical communication.
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Who knows, maybe someday all narwhals will end up with horns, male and female alike.
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For now, scientists aren't sure why some females end up with tusks, or why some males have two of them.
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The answer may be revealed in time, depending on which whales seem to be gaining or losing tusks over the generations.
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For now, narwhals remain one of the ocean's most mysterious animals.
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And even though I'm not a fan of a singular protruding tooth horn on most animals, it does suit the narwhal quite nicely.
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There's something truly beautiful about pondering the complexity of evolution throughout the billions of years life has existed on this planet.
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Whether it's wondering about the existence of a strange whale tooth, or pondering how a single cell becomes many,
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reproducing, mutating, giving rise to the sponges, worms, jellyfish, the invertebrates and the vertebrates,
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the cephalopods, birds, reptiles, mammals, and, eventually, us.
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There have been so many pivotal moments during the course of evolution that resulted in the world we know today.
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And these moments are so fun to explore with the free-to-play game called Cell to Singularity.
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Cell to Singularity is a non-fiction game available on Steam, iOS, and Android that takes you through evolution,
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where you start as a single-celled organism and progress through the tree of life.
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Each biological upgrade brings you closer to engulfing an entire planet with a civilization on the brink of technological singularity.
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I have to admit, I've become kind of obsessed with this game.
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I'm not normally one for phone games, I'm normally more of a doomscroller, but this snaps me out of doomscrolling.
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I much prefer to think about reptiles and whales and the entire concept of evolution than airplanes falling apart or Russian politics.
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It's easy to play and honestly really soothing, with nice music and satisfying progression.
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Every time you open up Cell to Singularity, you get to see how many entropy points you've earned and use them to unlock the next steps of evolution.
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And every piece that you unlock gives you a short description of that evolutionary moment, and reminds you of just how incredible every piece of the evolutionary puzzle is.
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The game also has limited time events that run weekly.
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In one of these events, you get to explore the Deep Sea, where it features the Dumbo Octopus, the Vampire Squid, and the beloved Giant Squid.
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Players can play the Deep Sea event again from April 10th to the 15th.
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I look forward to these in-game events every week.
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This science-based game also has a side simulation in space, where you can learn more about the planets, comets, and moons of the Milky Way with NASA-supported data,
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and a side simulation about dinosaurs, featuring the evolutionary history of prehistoric creatures throughout the Mesozoic Era.
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Come play Cell to Singularity today using the link in the description.
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The game is available for free on iOS, Android, and Steam.
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By downloading the game using this link, you're getting a fun new game, while directly supporting this channel at no cost to you.
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And if you make sure to use our link, you get to support this channel through sponsorship money instead of your own.
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Plus once you get started, you'll see how fun Cell to Singularity really is.
Para quem é este vídeo?
Este vídeo é ideal para aprendizes de inglês intermediários e avançados que buscam expandir seu vocabulário técnico e praticar a compreensão de conversações informais com tons humorísticos. Ele é perfeito para quem quer combinar aprendizado de ciência com aprimoramento da fala, especialmente por meio de técnicas de shadowing, já que a narração é clara, com pausas estratégicas e uma variedade de termos interessantes.
Palavras e expressões para roubar (e usar!)
- Bamboozled: Enganado de forma engenhosa. Exemplo: "Ela foi bamboozled pelo anúncio falso."
- Hardcore: Duro, resistente. No contexto: "Os narvais são animais hardcore por nadar em profundidades extremas."
- Collapsible: Que se encolhe ou fecha. "As costelas colapsíveis dos narvais ajudam na pressão alta."
- Endowed with: Dotado de. "Os narvais são endowed with dentes únicos."
Essas expressões são úteis para enriquecer a fala e entender conteúdos informativos em inglês. Pratique-as em frases próprias!
Como acertar o sotaque: dicas práticas
O narrador usa uma pronúncia clara, com ênfase em palavras-chave como narwhal (nárfwal) e tusks (tascs). Para imitá-lo, use a técnica de shadowing: reproduza o vídeo, pause e repita frases imitando o ritmo e a entonação. Sites de shadowing como o shadowspeaks podem ajudar a treinar essa habilidade, mas mesmo com o vídeo original, pratique a sincronia. Observe como ele usa a entonação para dar ênfase a fatos surpreendentes, como "that spiraling horn is actually a tooth" – a palavra "actually" é pronunciada com mais força para chamar atenção. Isso torna a fala mais natural e expressiva. Lembre-se: a chave é a repetição constante, até que o fluxo fique automático.
Aprender inglês com vídeos é uma forma eficaz de combinar diversão e aprendizado, e com técnicas como o shadow speak, você melhora não só a pronúncia, mas também a fluência. Dê um passo adiante e transforme cada vídeo em uma aula de prática!
O que é a Técnica de Shadowing?
Shadowing é uma técnica de aprendizado de idiomas com base científica, originalmente desenvolvida para o treinamento de intérpretes profissionais. O método é simples, mas poderoso: você ouve áudio em inglês nativo e repete imediatamente em voz alta — como uma sombra seguindo o falante com 1-2 segundos de atraso. Pesquisas mostram melhora significativa na precisão da pronúncia, entonação, ritmo, sons conectados, compreensão auditiva e fluência na fala.