are possibly the most specialised creatures on Earth 可能是地球上最奇特的动物

246. They are the cave specialists -
     它们都是洞穴专家
247. troglodytes, animals that never emerge from the caves or see daylight.
     穴居动物——从不出洞并且 永远不见天日的动物
248. These troglodytes from Thailand
     泰国的这些穴居动物
249. are possibly the most specialised creatures on Earth
     可能是地球上最奇特的动物
250. for they live only in cave waterfalls.
     因为它们只生活在洞穴瀑布中
251. The entire population of these cave angel fish
     世界上所有的洞穴天使鱼
252. seems to be restricted to just two small caves.
     可能只存在于两个较小的洞穴中

来自《行星地球 第一季 第四集 Planet Earth S01E04 洞穴》第 249 行