英语听力：自然百科 大堡礁 堡礁内外(16)（在线收听）

But that pales into insignificance when compared to the daily vertical migration of these microscopic animals called zooplankton.

但是当和每天在珊瑚礁墙上垂直活动的浮游生物相比它显得又是那么微不足道。

At sunset,all of these tiny creatures swim upwards,and, under cover of darkness,they graze on floating algae close to the surface.

日落之时所有这些微小的生物都向上游,在黑暗的掩护下,它们去吃靠近水面的海藻。

Many of them are fish larvae.

它们中有很多是鱼类的幼虫。

In fact, almost every fish species on the Great Barrier Reef starts life in the plankton.

事实上大堡礁上的几乎每种鱼的生命都是从浮游生物开始的。

There are billions upon billions of them making the roundtrip, the greatest daily migration on Earth.

每天都有数十亿只浮游生物进行着这场双程旅行，这是地球上最伟大的动物迁徙。

They all travel an extraordinary distance,size for size, it would be like me running a marathon twice a day.

它们都要游非常远的距离，如果按比例算的话就像我每天跑两次马拉松一样。

That's if they're not caught on the way up.

但是前提是它们在路上没有被捕食。

On the reef wall, at about 150 metres deep,are huge sea fans.

在珊瑚墙上，大约150深处是巨大的柳珊瑚。

They look like plants, but they're colonies of animals,whose branching arms capture the rising plankton.

它们看起来像植物，但是实际上是动物的栖息地，它们的枝叉都被上浮的浮游生物占领了。

Hidden amongst the branches is a pygmy seahorse.

躲藏在树枝之间的是一只小海马。

It's a tiny fish that also feeds on plankton.

它们是一种以浮游动物为食的鱼类。

At little more than a centimetre long, fully grown,it's one of the world's smallest fish.

它们长成也不超过一厘米长，它是世界上最小的鱼之一。