The pig-nosed turtle feeds on a wide variety of foods, including aquatic plants and the leaves, flowers, fruits and seeds of riverside vegetation, as well as insects, crustaceans, molluscs, worms and fish. Mammals may also sometimes be taken, possibly as carrion (4) (7) (8) (9) (12), and younger individuals tend to eat a higher proportion of animal material than adults (9). In addition to its use as a snorkel, the unusual snout is equipped with sensory receptors that allow the turtle to locate prey in murky water or sand (9). The pig-nosed turtle does not swim like other freshwater turtles, but instead ‘rows’ itself through the water with the paddle-like forelimbs, in the manner of marine turtles (8). It also occupies a much larger home range than other freshwater turtles, covering up to ten kilometres of river, and may move into adjacent wetland areas during the wet season (13).
The pig-nosed turtle reaches maturity at about 14 to 16 years, at a carapace length of around 30 centimetres (9). Nesting usually occurs in the dry season, from July to November in Australia, or September to February in Papua New Guinea (7) (8) (9) (12), and each female will lay two clutches a year, but only breed every other year (14). The nest is built at night, the female excavating a shallow chamber in sand or mud close to water, into which are laid around 4 to 39 white, spherical eggs (7) (8) (9) (12). The sex of the offspring is determined by the temperature at which the eggs are incubated, with higher temperatures producing females, and lower temperatures producing males (7) (8) (9) (15). Incubation lasts from around 64 to 102 days (7) (8) (15), but, unusually, the fully developed embryos often delay hatching, entering a period of arrested development until stimulated to hatch by rain or flooding, which usually signals the start of the wet season (4) (7) (15). Hatchlings measure between 5.2 and 5.9 centimetres in length (8).