有一天直布罗陀海峡会再次关闭
and then the Mediterranean will disappear oncemore.
然后地中海又会再一次消失
Today's oceans are far more than just reservoirs ofwater
但是海洋并不仅仅是蓄水池
that fill and empty as thecontinents move.
随着大陆移动要么灌满水要么干涸
They are crucial for the way the planet works and for the existence of life itself
它们对于地球来说 对于生命本身的存在来说都很关键
To understand why, you have to see them not as individual seas,
为了了解原因你不可以将它们看作是单独的海域
but as a whole, one single system.
而是看做是整体，一个系统
Even though we can't live beneath the waves,
虽然我们不能在海浪下生活
these vast bodies of water are vital to our very existence.
这片广阔的海水对于我们的存在来说非常重要
Much of that is down to a group of ocean inhabitants that are surrounding me.
很大一部分原因是因为海洋地下的一群生物 生活在我们身边
Single-celled organisms so small they're invisible to the naked eye.
单细胞有机体非常小肉眼是看不到的
They're known as phytoplankton.
它们被称作是浮游植物
