Description Galápagos tortoises are the giants of the tortoise world. They have a large bony shell of a dull brown or gray colour. The plates of the shell are fused with the ribs in a rigid protective structure that is integral to the skeleton. Lichens can grow on the shells of these slow-moving animals. Tortoises keep a characteristic scute (shell segment) pattern on their shells throughout life, though the annual growth bands are not useful for determining age because the outer layers are worn off with time. A tortoise can withdraw its head, neck, and fore limbs into its shell for protection. The legs are large and stumpy, with dry, scaly skin and hard scales. The front legs have five claws, the back legs four. Galápagos tortoises possess two main shell forms that correlate with the biogeographic history of the species group. They exhibit a spectrum of carapace morphology ranging from “saddleback” (denoting upward arching of the front edge of the shell resembling a saddle) to “domed” (denoting a rounded convex surface resembling a dome). A Galápagos tortoise can go without eating or drinking for up to a year because it can store food and water in its body. Because they are cold-blooded like other reptiles, they like to soak in the sun to warm up. At night, they may rest partially submerged in mud, water, or brush to keep warm during cool evenings. Mud wallows can also keep a tortoise cool during the day.
Status Galapagos tortoises (Chelonoidis nigra) are classified as an Endangered Species by the United States Fish & Wildlife Service (USFWS). Their IUCN classifications range from “extinct in the wild” to “vulnerable,” and they are listed on Appendix I of the Convention on International Trade in Endangered Species (CITES).