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  • Thanks to Brilliant for supporting this episode of SciShow.

  • Go to Brilliant.org/SciShow to level up your STEM skills this year.

  • [♪ INTRO]

  • Commercial whaling was really bad for whales, especially sperm whales.

  • People killed so many of them in the 19th and 20th centuries that even 10 years after hunting was stopped,

  • there were less than a third as many sperm whales as there were before

  • And their populations are still recovering today.

  • But not only did whaling land sperm whales on the endangered species list,

  • it may have caused some major problems for us too, by making climate change worse.

  • And that's because all those whales were helping cool the planet by doing a lot of

  • what every animal does best: pooping

  • While the blue whale is the largest whale in the ocean, sperm whales aren't exactly tiny.

  • They grow to be up to 18 meters long and weigh around 35 thousand kilograms

  • And, no surprise here, they need to eat a lot to reach such massive proportions.

  • Each whale consumes around 200 tons of food a year.

  • Yes, I said each whale.  

  • Luckily, they are excellent divers, so they can feast on the buffet of creatures,

  • like squid and octopus, that live thousands of meters down.

  • These yummy critters are full of nutrients, including iron, something not always easy

  • to come by in the ocean.

  • They have tons of it because it gets bound up in the dark pigment in their ink.

  • And I promise that's not just a fun fact, it will become important in a moment.

  • Now, while sperm whales eat most of their food in the dark depths, they do all their other business at the surface.

  • That's because, when they're diving, their bodies shut down all non-essential functions to conserve oxygen.

  • And that includes expelling waste.

  • Also, it just so happens their poop is super loose and runnyWhich is a lovely visual!

  • Point is, because of its consistency, it floats around at the top of the water, instead of sinking.

  • And these floating, watery feces are packed full of iron because the whales don't need

  • all the stuff they get from those deep sea noms.

  • About 90 percent of it gets pooped out. You know what does need iron? Plants.

  • It's an essential nutrient for photosynthesis.

  • So all the tiny photosynthesizers that live in the oceancollectively known as phytoplankton, love iron.

  • They don't care if it's from runny whale poop.

  • In fact, in some spots in the ocean, these tiny plants literally can't get enough of the stuff.

  • The dissolved iron in the water is so low that it keeps their populations from growing

  • That's because they require a specific form of iron called iron 2 that can easily dissolve in water.

  • And most iron 2 makes its way to the ocean via dust.

  • So places far from dusty lands, like the Southern Ocean that surrounds Antarctica, are extremely low in dissolved iron.

  • But whales can help with that!

  • Whales that live in low iron waters are like giant ocean crop dusters, fertilizing the water with their iron-rich poop.

  • When a bunch of iron becomes available, the phytoplankton reproduce like it's going out of style

  • They can double their numbers in a single day, creating swirls of green visible from space

  • We call this a bloom. These blooms do a bunch of photosynthesizing, so they build tons of sugar out of carbon dioxide and water

  • That means they suck up lots of dissolved carbon dioxide, carbon dioxide that went into the water from the air

  • These blooms end up feeding all sorts of ocean creatures, from microscopic animals to filter-feeding whales.

  • Eventually, though, all that yummy iron gets used up, and any phytoplankton that aren't eaten die.

  • At this point, the carbon in their bodies could get broken down by microbes and return to the atmosphere as CO2. 

  • But most of it sinks too quickly for that, so it ends up on the bottom of the ocean instead

  • And once it's down there, it stays down there.

  • That carbon gets trapped for a really long time, like, thousands of years or more.

  • So, the ultimate effect of whales pooping is less carbon dioxide in our atmosphere!

  • But it couldn't be that much, right?

  • Well, in 2010, researchers actually crunched the numbers to figure out just how much carbon

  • the 12,000 sperm whales living in the Southern Ocean were helping store.

  • They found that while these whales breathe out around 160,000 tons of carbon per year,

  • their poop fertilizes 400,000 tons of carbon storage.

  • That's a net storage of 240,000 tons a year!

  • Now, this is a drop in the bucket compared to the billions of tons of carbon humans pump into the air every year

  • So Southern Ocean sperm whales aren't making much of a dent in our climate problem all by themselves.

  • But they aren't the only whales in the Southern Ocean, and researchers believe that other

  • species found there may be doing the same thing

  • Also, there used to be over one million sperm whales worldwide before commercial whaling.

  • Just imagine the carbon storage potential if their populations rebounded to that level!

  • And we're working on that

  • Sperm whales are currently protected in the US under the Endangered Species Act and the Marine Mammal Protection Act,

  • and listed under the Convention on International Trade in Endangered Species of Wild Fauna and Flora.

  • And conservation groups continue to push for legislation to protect the animals, as well as

  • encourage companies to adopt whale-safe fishing gear and shipping practices and reduce ocean noise pollution.

  • So, the whales are already doing their part to combat climate change.

  • Now, thanks to science, we know that by helping them bounce back, we can do ours

  • And that's not the only reason this kind of research is important

  • It also helps us understand how ocean ecosystems function as a whole, and how quickly that

  • delicate balance can be disrupted

  • And that's just plain old important science right there!

  • Thanks for watching this episode of SciShow!

  • And thanks especially, to today's sponsor, Brilliant

  • Brilliant strives to make learning fun, they also offer dozens of interactive STEM courses through their website and app.

  • They've got a really cool intro course on statistics, for instance, which shows you

  • how scientists make decisions with limited data.

  • Statistics is one of the most important things in the world to understand!

  • But they've also got an entire library of math courses!

  • So you can learn how to best determine things like how much poop 12,000 whales make without

  • following them all around 24/7.

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  • [♪ OUTRO]

Thanks to Brilliant for supporting this episode of SciShow.

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鲸鱼粪便帮助我们的星球降温(Whale Poop Helps Cool Our Planet)

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    joey joey 發佈於 2021 年 06 月 30 日
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