It's graceful shell contains gas filled floatation chambers, 它那优美的外壳由充满空气的小室组成

197. A nautilus.
     鹦鹉螺
198. It spends it's days hiding four hundred meters down
     白天它躲在400米深的海底
199. But as night falls, it ascends up to the reefs, to look for food.
     到了晚上,它就游上来 到珊瑚礁附近寻找食物
200. It's graceful shell contains gas filled floatation chambers,
     它那优美的外壳由充满空气的小室组成
201. that control it's depth.
     使它可以控制深度
202. It's powered by a jet of water, squirting from a siphon
     它的动力来自虹吸管喷射的水流
203. but it travels shell first, so it can't see exactly where it's going.
     由于它是倒着游 所以它自己也很难看清楚自己要去哪里

来自《行星地球 第一季 第十一集 Planet Earth S01E11 海洋深处》第 200 行