 The highly aquatic nature of the group is typified by the presence of cloacal breathing in some species of the genera "Elseya" and "Rheodytes".However, some species, such as the eastern long-neck turtle ("Chelodina longicollis") from Australia spend significant periods of time on land and are considered highly terrestrial.The smaller members of the family include the Macleay river turtle ("Emydura macquarii") at around 16 cm, twist-necked turtle ("Platemys platycephala") at 18 cm and the western swamp turtle ("Pseudemydura umbrina") at 15 cm, whereas the larger species such as the "mata mata" ("Chelus fimbriata") and the white-throated snapping turtle ("Elseya albagula") both exceed 45 cm in shell length.