Darwin’s Last Steps on Galapagos

Today is Darwin Day, a celebration to commemorate the anniversary of the birth of Charles Darwin on 12 February 1809.

Blog, Beagle sketch

On 18 October 1835, Charles Darwin left Isabela island in Galapagos aboard the HMS Beagle. Although the Beagle was to spend two more days within what is now the Galapagos Marine Reserve, Darwin would not set foot on Galapagos lava again. After setting sail from the Galapagos Archipelago, Darwin and the rest of the crew on the Beagle didn’t see land until nearly a month later when the ship spotted Honden Island in the distance.

The Beagle took over five weeks to survey the whole of the Galapagos Archipelago, giving Darwin ample opportunities to go ashore. Darwin spent around 19 days exploring four of the Galapagos Islands: San Cristobal, Floreana, Isabela and Santiago. His first thoughts of San Cristobal were that “nothing could be less inviting than the first appearance. A broken field of black basaltic lava, thrown into the most rugged waves, and crossed by great fissures, is everywhere covered by stunted, sun-burnt brushwood, which shows little signs of life.”

He remarked that “all the plants have a wretched, weedy appearance” and that he “did not see one beautiful flower” on the Islands. However being a diligent collector, he managed to bring home 193 species of which 100 were described as new species. He was disappointed by the number of insects he found and described marine iguanas as “large, most disgusting, clumsy Lizards. They are as black as the porous rocks over which they crawl & seek their prey from the Sea”. It wasn’t until he later caught and dissected one that he discovered marine iguanas didn’t catch fish or other sea creatures; they in fact feed solely on algae. At the time he didn’t realise the importance of this discovery, being the only marine iguanas in the world.

Galapagos Wildlife: Marine iguana © Amy MacLeod (amy-macleod.com)
© Amy MacLeod

 

However, the more Darwin discovered of the Islands, the more he found them to be remarkable. He grew especially fond of the Galapagos giant tortoises and gained much enjoyment from sitting on their back and “then giving a few raps on the hinder part [so] they would rise and walk away”. The tortoises were also a source of food for the crew of the Beagle and they took over 40 from the Islands to eat.

It wasn’t until Darwin returned from his voyage on the Beagle that he studied and theorised about what he saw during his time in Galapagos. His collection of Geospizinae (now known as Darwin’s finches) from Galapagos were influential to his theory of evolution (although the mockingbirds that he collected were even more so). Darwin was informed by an ornithologist studying these specimens that what Darwin thought to be finches from several widely different families actually belonged to one remarkable new family. This realisation sparked Darwin to explore the idea that the different beaks of these finches indicated which island the bird was from and the different species had evolved different beaks in response to the food that was available on that island. Thirteen years after arriving home on the Beagle, Charles Darwin published his theories on evolution and natural selection in ‘The Origin of Species’.


by Lisa Wheeler