They are the key scavengers in this lake. 它们是湖里不可或缺的“清洁工”

162. and its marine-like forests of sponges
     再加上海底森林一般的海绵
163. Baikal seems more like an ocean than a lake.
     贝加尔湖看起来 更像是海洋 而不是湖泊
164. There are shrimp-like crustaceans - giant amphipods - as large as mice.
     这种长得像虾一样的甲壳动物 是一种大型端足类动物 它有老鼠那么大
165. They are the key scavengers in this lake.
     它们是湖里不可或缺的“清洁工”
166. The water here is just too cold for the bacteria that normally decompose the dead.
     由于湖水过于寒冷 分解尸体的细菌很难在此存活
167. Most rivers do not end in lakes
     大部分河流并非止于湖泊
168. but continue their journey to the sea.
     而是一直奔向大海

来自《行星地球 第一季 第三集 Planet Earth S01E03 淡水》第 165 行