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  • In tropical seas,

    在熱帶海洋中

  • flying fish leap out of the water,

    飛魚會躍出水面

  • gliding for up to 200 meters using wing-like fins,

    用翅膀似的鰭滑翔近 200 公尺

  • before dipping back into the sea.

    然後才又落下海洋中

  • In the Indo-Pacific,

    在印度洋到太平洋的海域中

  • a hunting sailfish can reach speeds of 110 kilometers per hour.

    一種獵殺型旗魚的速度可以達到時速 110 公里

  • That's 11 times faster than Olympic swimming champion Michael Phelps.

    這個速度比奧運會游泳冠軍 Michael‧Phelps 快上 11 倍

  • It can then stick up its spiny dorsal fin like a brake,

    然後牠能伸出刺狀背鰭來煞車

  • grinding to a dead halt, mid-swim.

    從游泳狀態急煞,變成完全靜止

  • Each of these physical feats is made possible by a fish's form,

    所有的身體技藝都是因為有魚的體型才能辦到

  • which in most species is a smooth, elongated body, fins, and a tail.

    大多數魚種外型是光滑、細長的身體,還有魚鰭跟尾巴

  • These features are shared across thousands of fish species,

    數千種魚類都有這樣的特徵

  • each introducing its own variations on the theme to survive in unique habitats.

    而為了在獨特的棲地生存,各魚種又發展出自己的變化

  • What makes these features so commonplace in fish,

    是什麼原因讓魚類都有這些特徵

  • and what does it reveal about the more than 33,000 fish species that inhabit earth's rivers, lakes, and seas?

    對於地球上河流、湖泊還有海洋中,超過 33,000 種魚類來說,這些特徵又透露了什麼訊息呢?

  • Fish can be split into two main groups,

    魚類可以分成兩大類

  • according to the type of motion they favor.

    根據牠們偏好的移動方式

  • The first is body and caudal fin driven motion,

    第一種是由身體與尾鰭驅動的移動方式

  • and most fish species, about 85%, fall into this group.

    而且大多數魚種,約略 85%,都屬於這一類

  • Here, the body and tail are the primary propelling forces,

    身體與尾巴是牠們主要的推進力

  • with fins mainly playing a stabilizing and steering role.

    而鰭主要扮演的是穩定與控制方向的角色

  • This configuration suits many open-water species,

    這種身體結構適合許多開放水域的魚種

  • which need speed, thrust and control for constant, efficient swimming.

    那裡的魚需要速度、突進能力跟控制力,以滿足經常且有效率的游泳需求

  • Eels lie at one extreme of this group.

    鰻魚就是這一大類的極端魚種

  • Known as anguilliform swimmers,

    牠是鰻行式泳者的代表

  • their entire bodies undulate to generate a wave-like motion.

    牠們整個身體呈現波浪狀起伏,產生水波狀的動作

  • Compared to anguilliform fish,

    相較於鰻行式游泳的魚種

  • species like salmon and trout, known as subcarangiforms,

    像鮭魚、鱒魚那類魚種,則是子鱒行式的游泳方法

  • use about two-thirds of their body mass to generate motion,

    利用身體 3 分之 2 的質量來移動

  • while carangiform swimmers, such as mackerel,

    而鱒行式的泳者,像鯖魚

  • only use about a third.

    只用了 3 分之 1

  • Typically, the less of its mass a fish uses to generate motion,

    通常魚在移動時,用到的身體質量越少

  • the more streamlined its shape.

    牠的身體越呈流線型

  • At the other end of the spectrum from eels are ostraciiform species like boxfish,

    跟鰻魚迥然不同的是甲殼式的魚種,像粒突箱魨

  • and thunniform swimmers like tuna.

    還有鮪行式的泳者,像鮪魚

  • In these fish, the tails, also known as caudal fins, do the work.

    這些魚種的尾巴,也就是尾鰭,負責推進

  • A tuna's tail is attached by tendons to multiple muscles in its body.

    鮪魚的尾巴透過肌腱與身體的多處肌肉連結

  • It powers the body like an engine,

    這使牠的身體像引擎一樣充滿力量

  • forcefully catapulting the bullet-like fish

    能把像子彈一樣的魚用力彈射出去

  • to speeds up to 69 kilometers per hour.

    速度可以達到時速 69 公里

  • The second major fish group relies on median and paired fin motion,

    第二大類的魚種則是仰賴奇鰭和偶鰭來移動

  • meaning they're propelled through the water predominantly by their fins.

    意思是牠們主要是透過鰭在水中推進

  • Fins allow fine-tuned movement at slow speeds,

    鰭可以讓牠們精準地慢速移動

  • so this propulsion is typically found in fish

    所以通常會用這種方式推進的魚

  • that have to navigate complex habitats.

    通常需要在複雜的棲地中航行

  • Bottom-dwelling fishes, like rays, fall into this group;

    底棲魚類,像是魟魚就屬於這一大類

  • using their huge pectoral fins, they can lift themselves swiftly off the sea floor.

    利用牠們巨大的胸鰭,牠們可以把自己迅速地從海底抬升

  • That conveniently allows them to inhabit shallow seas

    這方便牠們居住在淺海地區

  • without being buffeted about by waves.

    而不會被海浪衝擊

  • Similarly, shallow-water flatfish use their entire bodies

    一樣道理,淺水比目魚會把牠們的整個身體

  • as one big fin to hoist themselves up off the sand.

    當做一個大魚鰭,讓自己能從沙地升起

  • Ocean sunfish lack tails,

    翻車魚沒有尾巴

  • so they move around slowly by beating their wing-like median fins instead.

    所以牠們只能透過拍打牠們那像翅膀一樣的奇鰭來緩慢移動

  • Similar movements are shared by many reef species,

    許多珊瑚礁魚種也有相似的動作

  • like the queen angelfish,

    像額斑刺蝶魚 (女王神仙)

  • surgeonfish,

    擬刺尾鯛 (藍倒吊)

  • and wrasse.

    還有隆頭魚科

  • Their focus on fins has taken the demand off their bodies,

    他們都聚焦在鰭上頭,所以不需要注意體型發展

  • many of which have consequently evolved into unusual and inventive shapes.

    結果許多魚種都演化出不尋常、有創意的外型

  • There are fishes within both groups that seem to be outliers.

    這兩大類魚種中,都有一些看起來不屬於該類別的魚種

  • But if you look closer,

    但如果你仔細看

  • you'll notice that these common traits are disguised.

    你會注意到這些共通特徵只是被偽裝起來了

  • Seahorses, for instance, don't appear fish-shaped in any conventional way,

    以海馬為例,牠們的外型不是正常的魚類體型

  • yet they use their flexible dorsal fins as makeshift tails.

    但牠們會用牠們靈活的背鰭作為臨時的尾巴

  • A pufferfish may occasionally look more like a lethal balloon,

    河豚偶爾看起來像顆致命的氣求

  • but if it needs to swim rapidly, it'll retract its spines.

    但如果牠要快速游動,牠會把尖刺收回來

  • Handfish look like they have legs,

    臂鉤躄魚科看起來好像有腳

  • but really these limb-like structures are fins,

    但這些看起來像四肢的構造其實是鰭

  • modified to help them amble across the sea floor.

    改造成能幫助牠們在海底漫步的形狀

  • For fish, motion underpins survival,

    對魚來說,移動是生存的根本

  • so it's become a huge evolutionary driver of form.

    所以移動方式變成驅使牠們外形演進的重要因子

  • The widespread features of fish have been maintained across tens of thousands of fish species,

    魚類最普遍的特徵被保留在成千上萬的魚種中

  • not to mention other ocean-dwelling animals,

    更不用說其他居住在海洋中的動物

  • like penguins,

    像企鵝

  • dolphins,

    海豚

  • sea slugs,

    海參

  • and squids.

    跟烏賊

  • And that's precisely because they've proven so successful.

    那更明確的指出,因為牠們證明了這樣的演化很成功

In tropical seas,

在熱帶海洋中

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B2 中高級 中文 美國腔 TED-Ed 魚種 魚類 身體 尾巴 特徵

【TED-Ed】為什麼魚會長得那副魚樣?(Why are fish fish-shaped? - Lauren Sallan)

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    Evangeline 發佈於 2018 年 11 月 05 日
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