Crabs feed on dead skin on the iguana's back 红石蟹以海鬣蜥背上的死皮为食

139. There are more than 7,000 individuals on Fernandina alone.
     仅在费尔南迪纳岛上 就有超过七千只海鬣蜥
140. And by bringing nutrients from the sea to the land,
     它们往返近海获取食物养活自己
141. the iguanas help other animals to survive here, too.
     同时还帮助了其它动物在此生存
142. Crabs feed on dead skin on the iguana's back
     红石蟹以海鬣蜥背上的死皮为食
143. and, in turn, provide a welcome exfoliation service.
     反过来也热情地为它们提供去角质服务
144. While smaller lizards prey on the flies that pester the colony.
     小型蜥蜴还捕食纠缠海鬣蜥的苍蝇
145. But not all the relationships on this island are so harmonious.
     但岛上的生存关系并不是都如此和谐

来自《行星地球 第二季 第一集 Planet Earth S02E01 岛屿》第 142 行