is also one of the hardest to see. 也最难寻觅它们的踪迹

248. And, among them, inevitably,
     而这之中 必然存在
249. are hunters.
     猎食者
250. One of the most voracious nocturnal predators
     其中最贪婪的夜间捕食者
251. is also one of the hardest to see.
     也最难寻觅它们的踪迹
252. This mysterious creature
     这个神秘的生物
253. hardly ever appears on the surface of the dunes.
     鲜少出现在沙丘表面
254. But there are signs on the sand that can give it away.
     但沙子的移动 却泄露了它的行踪

来自《行星地球 第二季 第四集 Planet Earth S02E04 沙漠》第 251 行