A baby sea urchin. A pleuteus

有個長腕幼蟲 (海膽幼體)，

Blind and deaf, its sole purpose is to find the right place to land.

看不見也聽不到，想找到好地方落地生根，

Here's what it will become, an adult sea urchin.

它將來會長成我們熟知的海膽，

Basically a rugged ball of spines, built to survive in some of the harshest environments

海膽基本上像一顆粗糙的球，上面佈滿刺，

in the ocean.

讓牠們得以在艱困的海洋環境存活下來，

Like their cousins the sea stars and sand dollars, sea urchins have little tube feet.

海膽跟近親海星和海參一樣，有小小的管狀腳，

They use them to move around... and pull kelp into their mouths.

用來移動、把海草送進嘴裡，

And between their spines are pincers called pedicellariae that they use to groom themselves.

在尖刺之中有稱為「叉棘」的一種鉗狀物體，海膽用它清理表皮，

Each spring males release clouds of sperm and females release huge numbers of eggs.

每年春天雄海膽會放出團團精蟲；雌海膽則釋出數量龐大的卵子，

A tiny percentage of them find each other in the open ocean.

其中有一小部分的精蟲與卵子得以在偌大海洋中碰到彼此，

The fertilized egg grows and eventually hatches.

受精卵成長、孵化，

An embryo swims for its life.

為了生存，海膽胚胎持續在海裡游泳，

As it grows, it takes on the shape of a little lunar lander.

在生長時，海膽的形狀會很像月球登陸艙，

It can swim for weeks or months like this, covering huge distances, feeding on algae

牠們游泳的時間可以長達幾周甚至幾個月，涵蓋很遠的距離，

along the way.

同時以海藻維生，

Meanwhile, a microscopic adult urchin is growing inside its own teenage self.

海膽稍長時，微小的成熟身體也同時在體內成長，

The pluteus needs to land somewhere before the adult inside it grows too big.

在成熟身體長太大之前，海膽幼體必須在海床著陸，

The ocean currents drag it towards shore and into the pounding surf.

洋流把牠帶往岸邊，來到波濤洶湧的海面上，

That turbulence plus the smell of tasty kelp lets the pluteus know, it's time.

海浪淘淘拍打與海藻的香味讓海膽了解時候已到，

It stops swimming.

牠停止游泳，

It falls to the seafloor.

下降至海床，

Then something really weird happens.

接著奇怪的事情發生了：

From inside, tube feet reach out

管狀觸角從裡面冒出來，

It pulls itself inside out, like a sock.

把自己向外拉出，像伸出襪子

Here's a sand dollar doing the same thing.

沙錢也會做同樣的事情，

A miniature adult emerges

接著一個迷你成體海膽出現了，

And then, after so much change and tumult, time kind of … stands still.

經過大幅變動後，仍然靜止不動，

Unless an urchin is eaten or gets sick, it can grow for centuries.

海膽可以存活好幾世紀，除非生病或被吃掉，

Having survived the long odds of youth... it's now practically immortal.

若能活過幼年時期，海膽幾乎可以長生不死，

Hey, this is Amy!

大家好我是 Amy，

Check out more of our ocean stories.

請大家看看其他海洋動物的影片，

Like this one, about how pygmy seahorses make themselves nearly invisible.

例如這片介紹侏儒海馬可以讓自己變得幾乎隱形，

Or this one, about how sea otters' fur keeps them warm in frigid water.

或是另一個：水獺的毛使牠們能在冰冷的水裡維持體溫，

Thanks for watching!

謝謝收看！