June 29, 2000.
Getting There Is Only Half The Battle
This is Roger Payne speaking to you from the Odyssey as we make our way to Baltra Island in the Galapagos.
When the tips of the first volcanoes of the Galapagos Archipelago first appeared above the sea they had never been connected to the continent and were totally devoid of life. When Europeans first discovered these islands everything found here had had to travel from somewhere else, in most cases from the South American mainland 960 km (600 miles) to the east.
The first living things to cover the distance to the islands and colonize them successfully must have been cliff-nesting seabirds and sealions. But they would have used the new islands only as places to perch, nest, or haul out. The first terrestrial organisms whose whole lives took place entirely on the Galapagos islands must have been plants such as bacteria, molds, ferns, mosses and lichens, These presumably arrived as spores carried on the wind. Lichens need moisture, sunlight, air, and some nutrients. When the first lichen spores sifted down onto the Galapagos Islands they would have landed on otherwise pure lava rock devoid of all life. However, sea bird droppings might have provided the required nutrients.
One importance of lichens is that they manufacture soil, albeit it very slowly. Nevertheless time cures all ills and given a hundred thousand years or so, enough soil would have washed down and accumulated in low lying places to satisfy the needs of many higher plants that were arriving as seeds or whole plants.
That's all for tonight. Tomorrow I'll talk about how the bigger animals like the giant tortoises probably got here.
© 2000 - Roger Payne