30 sailfish have surrounded a ball of sardines.三十条旗鱼包围了一群沙丁鱼

a ball of:一团

The car was engulfed in a ball of flames.

汽车陷于一团火球中。

People consider me a ball of energy!

人们认为我是能量球!

To catch their prey requires more than speed alone.要捕捉猎物不光要速度快而已

more than:不只是；很；超过

We know more than you do.

我们比你知道的多。

He needs me more than ever.

他比任何时候更需要我。

Knocking it off balance, separates it from the shoal.让猎物失去平衡和鱼群分开

knock off:<非正>降低；<非正>将…击打掉

He has knocked 10 seconds off the world record...

他将世界纪录缩短了10秒。

My health compels me to knock off work.

我的健康状况迫使我不得不停止工作。

separate from:从...分开

Violent prisoners are kept separate from the others.

有暴力行为的囚犯隔离囚禁。

Korea is separated from China by the Yalu River.

朝鲜和中国只有鸭绿江一水之隔。