Charles Darwin journeyed to the Galapagos Islands off the coast of Ecuador. Here he discovered cacti the size of trees. He encountered iguanas that swam and fed on underwater algae. Darwin discovered the largest land tortoises in the world. He observed differences in beak shapes of 14 species of finches. Darwin’s research revealed that beak shape corresponds to the food each bird eats. Finches that eat nuts and seeds have short, thick beaks to crack shells. Those that feed on cactus plants have longer beaks for reaching between the spines. Finches that eat insects have smaller, pointed beaks. The woodpecker finch uses twigs to pry food from bark.