Chelodina expansa Gray 1857: Broad-Shelled Turtle, Giant Snake-Necked Turtle

Australia's largest snake-necked turtle, Chelodina (Macrochelodina) expansa (Family Chelidae), occurs broadly through the inland rivers and billabongs of eastern and southeastern Australia. The species is cryptic in habit, yet occupies waters heavily exploited and regulated by humans. Traditionally considered a riverine species, recent studies demonstrate that it is more frequently represented in permanent lakes and billabongs connected to main river channels. Typical of many freshwater turtles, C. expansa displays delayed maturity and high adult survivorship. It is carnivorous and feeds primarily on fast-moving prey such as crustaceans and fish, but will also consume carrion. The reproductive biology of C. expansa sets it apart from most other turtles; in response to low temperatures, embryos enter a diapause, which enable them to survive over winter in nests, resulting in a year-long incubation period. Chelodina expansa has lower population densities than sympatric turtle species, which may increase its vulnerability to threats. Persistence of C. expansa relies on habitat quality and longitudinal connectivity of freshwater systems in southeastern Australia.