The Galápagos tortoise (Chelonoidis niger, with several living subspecies) is the largest living species of tortoise, native to the Galápagos Islands off Ecuador, where individuals can weigh over 400 pounds (180 kg) and grow to more than 5 feet (1.5 m) long. These giant reptiles are famous for their remarkable longevity, often living well over 100 years, and their slow, deliberate movements as they graze on grasses, cacti, and other vegetation. Different populations evolved distinct shell shapes—domed shells in tortoises from lush, high-altitude habitats and saddleback shells in those from drier lowland islands, allowing them to reach higher vegetation like cactus pads. Once hunted heavily by sailors and whalers for food (they could survive for months aboard ships without eating), and later threatened by introduced predators and habitat loss, Galápagos tortoises became a symbol of conservation success as breeding and reintroduction programs, notably at the Charles Darwin Research Station, helped several subspecies recover from the brink of extinction. They also played a key role in Charles Darwin's observations that contributed to his theory of evolution by natural selection.
