When the Galapagos were discovered by Spanish explorers in 1535, hundreds of thousands of giant tortoises roamed the islands. Survivors of prehistoric times when reptiles were of enormous size, some of the tortoises grow to 4 feet in length and weigh as much as 500 pounds. They may live for more than a century. In the 1700’s and early 1800’s, their numbers were drastically reduced by pirates and whalers who filled their ships with live tortoises to provide fresh meat. Slaughter continued as late as 1930’s. Traders killed the tortoises for their meat and clean-tasting oil and scientists killed them in the name of research.