In the middle of the Pacific Ocean, around 1000 km to the west of South America, there is a group of volcanic islands. The Galapagos Archipelago. The islands are considered the cradle of evolution. Nowhere else you could find such a rare variety of animals, including diving iguanas, giant tortoises with snake-like necks, and albatrosses which you normally expect on the open ocean.
The secret to this biodiversity lies hidden in the Pacific. Two mighty ocean currents keep a firm grip on the Galapagos. The ice-cold Humboldt Current from the Antarctica brought animals to the Galapagos which would normally just exist in cold regions. It dominates one half of the year. The other half of the year, the warm, tropical Panama Current reigns over the remote, ancient islands and brings its own animals with it. These powerful currents alternate every six months, inverting the life in the Galapagos!
Tropical oceans are typically low in nutrients, usually resulting in extensive biodiversity, but small fish populations. It’s a different story on the Galapagos: The Humboldt Current from Antarctica makes its way to the Galapagos for six months, bringing vast volumes of nutrients and triggering tremendous algae growth – a natural phenomenon that feeds giant schools of fish and is unique throughout the Tropics. Thanks to these algae, the marine iguana exists on the Galapagos. Through adaptation, evolution created the earth’s only reptile capable of eating just algae and diving.
As much as the Humboldt Current benefits the marine life, it poses an equally great challenge for the land dwellers: There is hardly any rain during its stay, and its cold water makes for some odd weather conditions. Humidity can just be found on the volcanic peaks of the younger islands, where the Garua – a persistent mist- reigns. This is the time when the local giant tortoises embark on a hazardous trek into the misty highlands to find food.
Yet, the tide turns every six months in the Galapagos Islands: The warm, tropical Panama Current brings intense rain: finches, giant tortoises, land iguanas, and Galapagos carpenter bees can now enjoy an abundance of food. Meanwhile, it’s a completely different story for the marine dwellers: When the Panama Current arrives, tropical conditions return to the underwater world. Most of the fish withdraw – the lack of nutrients means no algae, and the attractiveness of the Galapagos Islands quickly evaporates. However, most of marine life can’t leave that easily. The marine iguana has it tough. Its preferred food, algae, is now in short supply, but that’s only one of its problems, with strong surges pushing the weakened lizards to their absolute limits. The battle for survival begins.
Whether on land or at sea, no one can escape the grip of the ocean.