sifting through the droppings for nutrients. 它们从粪便中过滤营养物质

86. These in turn become food for giant cave centipedes,
    这些蟑螂也接连成为了 洞穴大蚰蜒的美餐
87. some more than 20 centimetres long.
    有的蚰蜒能长到20厘米长
88. Bizarrely, there are crabs here, too,
    奇怪的是 这里甚至还有螃蟹
89. sifting through the droppings for nutrients.
    它们从粪便中过滤营养物质
90. All these animals spend their entire lives within the cave.
    所有这些动物都在洞穴内度过一生
91. They're totally dependant on the digested remains of food that's brought here from outside.
    它们完全依赖的食物消化残渣 都是来自于外界
92. Each evening in just two hours
    每天傍晚 只是前后2小时内

来自《行星地球 第一季 第四集 Planet Earth S01E04 洞穴》第 89 行