Big Pacific

(waves crashing) (relaxing music) -

Narrator

The Galapagos are home to the world's only marine iguana. (relaxing music) It dives down to more than 15 meters, where meadows of rich algae offer all the sustenance it needs. Sharp claws keep it anchored to the bottom in the strong ocean swell, while a blunt nose allows razor teeth to cut close to the rocks, scraping off the nutritious coating of algae. (relaxing music) The marine iguana can hold its breath for more than an hour, but a typical dive last no more than ten minutes. (relaxing music) To their ancestors, the sea was hostile. They were most likely tree dwellers, cast away here on a raft of driftwood from South America, a thousand kilometers away. (relaxing music) But with nothing to eat on this barren rock, they were forced to take up the life aquatic. (relaxing music) (waves crashing) There's a reason its dives are typically brief. Iguanas are cold blooded. Basking is vital. They get a double dose of heat from the sun's rays and the warm, black rocks. Surviving on a diet of salty seaweed with no permanent fresh water would be impossible without another evolutionary trick. The build up of salt in its bloodstream is filtered by a gland in its nose, and then expelled. The key to survival in a sneeze.