中級 1348 タグ追加 保存
動画の字幕をクリックしてすぐ単語の意味を調べられます!
単語帳読み込み中…
字幕の修正報告
Sunning themselves on rocks or waddling awkwardly across the beach,
it's easy to think of these immobile mammals less as sea lions,
and more as sea house cats.
But don't be fooled by their beachside behavior.
Under the waves, sea lions are incredible endurance hunters.
Hurtling around at speeds from 4 to 18 miles an hour
and hunting for up to 30 hours at a time,
these majestic mammals live up to their name.
And thanks to a suite of physical adaptations,
finely tuned over millions of years, they make for resourceful foragers.
To find their favorite food,
sea lions hunt much deeper than many of their semi-aquatic peers.
With some species diving to depths of nearly 400 meters,
they're able to cope with the mounting pressure
by collapsing their pliable rib cage, and compressing a pair of springy lungs.
This pushes air up through the smaller airways,
collapsing rings of cartilage as oxygen travels out from the lungs,
to be held in the larger, upper airways.
Upon surfacing, this air will be used to re-inflate the lungs,
but for now their heart slows down to preserve oxygen.
Blood flow is redirected towards only the most essential organs
like the heart, lungs, and brain,
which rely on reserve oxygen stored in blood and muscle.
Once they arrive at their hunting ground,
sea lions depend on their superior vision to find their prey.
Most mammal eyes have a structure called a lens–
a transparent, convex structure whose shape refracts light to enable sight.
In humans, this lens is curved to process light waves traveling through air.
But sea lions need to see their best at hundreds of meters deep.
To accommodate, their eyes have a much rounder lens to refract light underwater,
as well as teardrop-shaped pupils
which can expand to 25 times their original size.
This lets in as much light as possible,
helping them pinpoint their prey in even the dimmest conditions.
But once they've closed in,
they rely on something akin to a sixth sense to actually catch their meal.
Their whiskers, or vibrissae,
are composed of keratin and full of nerve fibers
that run deep into the connective tissue of their face.
Sea lions have full directional control over these whiskers,
which can lie flat against their face, or stick out at a 90-degree angle.
When properly tuned,
these whiskers can sense the slim trails of moving water fish leave in their wake.
And they're precise enough to let blindfolded sea lions
tell the difference between objects less than two centimeters different in size.
With these tools a healthy sea lion can catch generous helpings of fish
such as anchovy, mackerel, and squid on every outing.
And with their exceptional memories, they can remember multiple hunting grounds,
including those they haven't visited in decades.
This memory also extends to breeding territories and birthing areas,
as well as which neighbors are friend and foe.
There's even evidence that sea lions can remember how to perform tasks
after 10 years with no practice in between,
letting them navigate old stomping grounds with ease.
Yet despite these incredible adaptations,
there are changes unfolding in their habitats
too rapidly for sea lions to handle.
As climate change warms the oceans, certain toxic algae species thrive.
This algae is harmless to the fish who eat it,
but for the sea lions which ingest those fish,
the algae's domoic acid can trigger seizures and brain damage.
Changing ocean conditions keep this algae blooming year round,
causing more and more sea lions to wash up on beaches.
This tragic discovery is just one of the many ways
the health of aquatic animal communities can help us
better understand Earth's oceans.
These red flags help us take action
to protect ourselves and other maritime mammals.
And the more we can learn about the changing ocean that sea lions inhabit,
the better equipped we'll be to help these clever creatures thrive.
コツ:単語をクリックしてすぐ意味を調べられます!

読み込み中…

The lovable (and lethal) sea lion - Claire Simeone

1348 タグ追加 保存
高詩詩 2019 年 7 月 27 日 に公開
お勧め動画
  1. 1. クリック一つで単語を検索

    右側のスプリクトの単語をクリックするだけで即座に意味が検索できます。

  2. 2. リピート機能

    クリックするだけで同じフレーズを何回もリピート可能!

  3. 3. ショートカット

    キーボードショートカットを使うことによって勉強の効率を上げることが出来ます。

  4. 4. 字幕の表示/非表示

    日・英のボタンをクリックすることで自由に字幕のオンオフを切り替えられます。

  5. 5. 動画をブログ等でシェア

    コードを貼り付けてVoiceTubeの動画再生プレーヤーをブログ等でシェアすることが出来ます!

  6. 6. 全画面再生

    左側の矢印をクリックすることで全画面で再生できるようになります。

  1. クイズ付き動画

    リスニングクイズに挑戦!

  1. クリックしてメモを表示

  1. UrbanDictionary 俚語字典整合查詢。一般字典查詢不到你滿意的解譯,不妨使用「俚語字典」,或許會讓你有滿意的答案喔