becoming ever darker and damper, 越往下就越阴暗潮湿

173. and millions of species of insects,
     还有数百万种昆虫
174. exactly how many we have no idea.
     至于确切数量我们不得而知
175. The character of the forest changes as we descend,
     从上到下 森林的特点也在发生改变
176. becoming ever darker and damper,
     越往下就越阴暗潮湿
177. favouring different kinds of animals and plants.
     适合各种不同种类的动植物
178. Less than 2 percent of the sunlight reaches the floor,
     只有不到2%的阳光能够到达丛林地表
179. but even here there is extraordinary variety.
     即便如此 这里的生物种类也异常丰富

来自《行星地球 第一季 第一集 Planet Earth S01E01 从北极到南极》第 176 行