In 1831, Charles Darwin sailed on a ship. It was called the Beagle. He was a naturalist from England. He visited South America. His job was to collect and study animals, plants, and rocks. 

The ship reached the Galápagos Islands in 1835. Darwin visited four islands. San Cristóbal was the first. This island is made up of four volcanoes. It is dry and rocky. He found marine iguanas, small birds, and desert plants. On Floreana, he found more birds. They were different from the ones on the first island.

The volcano on Isabela Island was erupting when Darwin saw it. He collected land iguanas.

Then he went to Santiago Island. Here, he stayed the longest. He saw that the giant tortoises were different than the ones on other islands.

Darwin collected many plants and animals. How did they survive here? He wasn’t sure.

Darwin took his samples back to England. He shared them with other naturalists.