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In winter, the seas around Antarctica are so cold that they form a platform of ice twice the size of Europe.
冬天，南极洲周围的海域很寒冷，这里形成了一个两倍于欧洲大小的冰平台。
But in summer, just off the shores of the Antarctic Peninsula, the ice cover breaks up into millions of tiny ice floes.
但在夏天，南极半岛的海岸附近，冰盖分解成数百万个小的浮冰块。
It's an excellent place for a Weddell seal to rest up after a night's feed.
这是威德尔海豹晚饭吃饱后休息的绝佳去处。
The bay is sheltered, and the water calm.
海湾提供了方便，水面很平静。
But there are great dangers here. Killer whales.
但这里藏有很大的危险。虎鲸。
This pair of 15-year-olds are learning what is perhaps the most complex hunting technique in nature.
这双15岁的年轻虎鲸，正在学习可能是自然界中最复杂的狩猎技术。
After sizing up their prey, they assemble 30 metres away, and then launch an attack.
在对猎物进行估量后，它们在30米外集合，然后发动攻击。
They swim in tandem, synchronising their tail beats to create a wave.
虎鲸一起游泳，尾巴同步摆动，掀起一个波浪。
The seal is washed off, but it won't give up without a fight.
海豹被冲下冰块，但海豹不会就此不战而降。
The seal has escaped this time.
海豹这次很侥幸的逃脱了。
But for the young killer whales, help is at hand.
但对于年轻的虎鲸来说，后援就在旁边。
They live in multi-generational family groups,
虎鲸生活在多代共存的家庭之中，
led by an experienced female, who can be over 100 years old.
由一位经验丰富的雌性领导，她可以超过100岁。
Helped by her accumulated knowledge, the whales have become ruthlessly efficient.
在她积累的知识的帮助下，虎鲸变得无情和高效。
They have a 90% hunting success rate.
它们有高达90%的狩猎成功率。
But a killer whale needs to eat a seal a day, so this 14-strong family has a lot of hunting to do.
但是虎鲸一天要吃一只海豹，所以这个14口的家庭要进行很多次狩猎。
Spreading out, they spyhop to search the ice floes.
它们四散开来，搜寻浮冰。
When a seal is spotted, the scouts alert the family with a rallying call.
当发现海豹时，侦察兵发出召集声，提醒家人。
But if they are to catch a seal resting on such a large piece of ice, the hunters need to change their tactics.
如果它们要抓到在这么大一块冰上休息的一只海豹，猎人们需要改变它们的战术。
This time, they produce a sub-surface wave. It breaks the ice into smaller pieces.
这一次，虎鲸集体产生了次表面波。它将冰块破碎成更小的碎片。
But the seal still has a raft, and appears to be protected from any oncoming wave.
但是海豹还是在浮冰之上，似乎面对任何迎面而来的波浪可以受到保护。
The matriarch whale, however, has a plan.
然而，虎鲸女族长有个办法。
Working in a coordinated way, the pod push the seal's ice platform into clearer water.
采用相互合作的方式工作，鲸群合力推动海豹的冰台进入少冰的水中。
The matriarch now tries another tactic which will avoid injury blowing bubbles.
女族长现在又尝试一种策略，这样可以避免受伤，吹泡泡。
They disorientate the tiring seal. And the whales move in for the kill.
终于使疲惫的海豹迷失方向。鲸鱼开始杀戮。
Only about 100 killer whales in the world hunt using this technique.
世界上只有大约100头虎鲸使用这种技术捕猎。
It's an ingenious solution to the problem of finding prey here in the most extreme frozen habitat on Earth.
这是在地球上最极端的冰冻栖息地获得猎物的巧妙解决方案。
