6. Giant Tortoise

Next on our list of the longest-living animals is the giant tortoise. In the 1830s, while developing the theory of evolution through natural selection, Charles Darwin studied several animal species.

One of the animals he studied during his visit to the Galapagos Islands was a giant tortoise named Harried. Interesting fact: the tortoise lived to be 175 years old and passed away in 2006. Some specimens measure over five feet long and weigh over 500 pounds.

Over 200,000 giant tortoises formerly roamed the Galapagos Islands; today, just 10% of the original population remains, and four species are extinct. The good news is that the tortoise population has been rescued and will eventually recover.