Galapagos tortoises

Variation in shell morphology of Galapagos Tortoises

Tortoises on different islands of the Galapagos archipelago differed widely in shell morphology, particularly with respect to the curve of the back and the "saddle" above the neck. The Governor of the islands told Darwin that he could tell from which island any tortoise came, according to the shape of the carapace. In the three examples shown, both the Abingdon and Duncan forms feed on cactus on dry islands, whereas the Albemarle form feeds on vegetation closer to the ground on a wetter island. The former have upturned saddles, longer necks, and straighter backs. The latter have domed shells and shorter necks. [English names for the islands have been replaced by Spanish, and the island are now a protected reserve under the government of Ecuador].