The cave angel fish feed on bacteria in the fast flowing water keeping their grip with microscopic hooks on their fins. Food is often in short supply and troglodytes like the crab have to survive on whatever washes into the cave from outside. A salamander might not encounter food for several months, so when something does come along it can't afford to miss it. It's astonishing that these extraordinary cave dwellers manage to survive at all. But one cave is so inhospitable that one would not expect it to contain any life whatsoever. The water flowing out of the Villa Luz cave in Mexico is actually coloured white with sulfuric acid.


刺盖鱼以快速流动的水中的生物为食，它们用鱼鳍上极小的钩子来捕捉这些食物。食物常常短缺，所以穴居动物如螃蟹等为了生存对进入洞内的东西总是来者不拒。一条蝾螈可能几个月找不到食物，所以如果遇上一个猎物，它不能轻易放过。令人称奇的是，这些奇特的洞穴居民竟然能生存下来。但是有一个洞穴内环境极端恶劣，我们会认为它不会有任何生命存在。从墨西哥的维拉卢兹岩洞流出的水是白色的，因为里面含有硫酸。