marine iguanas graze on the sea floor. 所以海鬣蜥以海底的植物为食

133. Seagoing iguanas.
     海鬣蜥
134. They are vegetarians,
     它们是素食者
135. but since there's little food for them on the land,
     但由于岛上没有能吃的食物
136. marine iguanas graze on the sea floor.
     所以海鬣蜥以海底的植物为食
137. A big male like this one can dive to 30 metres
     这种体型的雄性海鬣蜥可潜到水下三十米
138. and hold his breath for half an hour.
     屏住呼吸长达半小时
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

来自《行星地球 第二季 第一集 Planet Earth S02E01 岛屿》第 136 行