..which they will certainly need. 这正是它们需要的

170. But over the coming days, the gobies transform themselves.
     但在接下来的几天里 虾虎鱼会改变自己
171. They change colour.
     颜色发生变化
172. Their mouth rotates and acts like a kind of suction cup...
     嘴部转动 如同一个吸盘
173. ..which they will certainly need.
     这正是它们需要的
174. Because the only way...is up.
     华山一条路 它们必须登上顶端
175. It is 30 metres to the top.
     垂直落差高达30米
176. They are only an inch long.
     而虾虎鱼身长只有不到3厘米

来自《行星地球 第三季 第四集 Planet Earth S03E04 淡水》第 173 行