which they use as a refuge from predators. 这里是它们躲避天敌的地方

217. they have become important shelters for many species.
     它们也成了许多动物的重要庇护所
218. After a day feeding in the open water
     经过一天开放水域的觅食之后
219. vast shoals of demoiselle fish return to the caves,
     大群雀鲷返回到洞窟中
220. which they use as a refuge from predators.
     这里是它们躲避天敌的地方
221. For these fish the caves are a night time retreat,
     对于这些鱼来说 洞穴是理想的过夜场所
222. but they're not the only commuters in here.
     但它们并非这里的唯一住客
223. There are other fish working to a different schedule.
     这里还有其它 按照不同日程表生活的鱼

来自《行星地球 第一季 第四集 Planet Earth S01E04 洞穴》第 220 行