These tortoises spend a large part of the day grazing in small groups (2); they eat a wide range of vegetation from grasses and flowers to cactus fruits (8). During the rainy season a lot of time is spent wallowing in shallow pools, and at night tortoises can be found in depressions dug into the ground (9). On some islands, Galapagos finches clean parasites from the skin of tortoises, which raise themselves up on their legs to facilitate this process (10). Males become territorial during the mating season (2), rivals will size each other up by standing tall on their legs and stretching their necks out, the taller tortoise will be dominant (10). Females lay their clutch of 2 to 16 eggs into nests dug into sandy ground; the nest is then covered over with soil and leaves and the hatchlings emerge around 4.5 months later (10). These giant tortoises are one of the longest-lived of all vertebrates and the oldest recorded individual reached the formidable age of 152 (3).