Adaptation

The second programme considers how Galápagos’s plants and animals managed to adapt to the harsh conditions they encountered. A CGI sequence demonstrates the life cycle of a typical Galápagos island. Born through volcanic activity, it rises from the ocean eventually reaching mountainous heights before sinking under its own weight and then finally eroding back into the sea. There are islands today which represent all stages of this history. The youngest, Fernandina, has a barren, volcanic interior. Marine iguanas have successfully colonised its shoreline by adapting to feed on seaweed and expel salt from a special gland. Santa Cruz is a middle-aged mountainous island, able to create its own rainfall and thus enabling plants to thrive. Attenborough demonstrates the forests of giant Scalesia, a relative of the dandelion, which flourish on its highland slopes. Scientists exploring lava tunnels just below the surface are still discovering new species. Older islands such as Española are smaller, drier and flatter. Its sandy beaches are used by Galápagos sea lions and waved albatross. Tortuga and Devil’s Crown are the eroded remnants of volcanic cones, close to disappearing into the sea. Their surrounding waters support coral reefs, fertilised by the erosion of sediments from the land. Submerged islands further to the east can still influence life. Whale sharks are thought to use them for navigation, but the reason why they pass through Galápagos waters is still unclear.