Giant South American Turtle

This turtle has a wide, domed shell designed for active swimming in moderate currents. Its coloration ranges from olive green to brown, often modified by algae attached to the scales. Its long neck retracts horizontally inside the shell, leaving part of the head visible, distinguishing it from turtles with a vertically retracting 'S'-shaped neck.

A social animal, the Giant South American Turtle lives in groups and undertakes massive migrations, numbering in the thousands, from flooded forests to sandy beaches during the breeding season. It is active during the day in the water, with peak activity in the late morning and afternoon, while females exclusively lay eggs at night. Outside the breeding season, the species feeds during the day.

Primarily herbivorous, it closely follows the flood cycle. During high water season, it feeds in flooded forests, lagoons, and swamps, consuming fruits, tree seeds, legumes, and green leaves. It supplements this plant-based diet by ingesting freshwater sponges, eggs, and sometimes acts as a scavenger by consuming dead fish.

Newborns appear to have a more omnivorous diet initially before their digestive system fully adapts to herbivory. During the breeding period, females almost completely stop feeding.

Reproduction is synchronized with the hydrological cycle: nesting occurs during the dry season when water levels are low, on elevated sandy beaches often reused year after year. Females dig flask-shaped nests 60 to 80 cm deep and deposit between 78 and 132 spherical eggs with parchment shells, although lower averages are sometimes observed.

Incubation lasts 45 to 48 days in sand reaching 60°C on the surface, with temperature determining the sex of the hatchlings (more females at higher temperatures), and hatching coincides with the beginning of the rainy season, guided by maternal aquatic vocalizations.