The Emydidae are the largest and most diverse family of Testudines. The family Emydidae includes more than 40 species in 12 genera. Members are distributed throughout North America, northern South America, Europe, northwestern Africa, and Asia. Emydids are the principle turtles sold through the pet trade. The pond slider (Trachemys scripta) has expanded its range through the careless release of pets into the wild. Many Asian species are threatened by over-collection of animals for sale in markets and into the pet trade.