Pet-shop turtles that slid into rivers worldwide
Red-eared sliders (Trachemys scripta elegans) are pond terrapins named for crimson ear stripes and a habit of slipping off logs into water. They evolved in the Mississippi basin and nearby Mexican drainages, yet pet releases seeded them on far continents. Shells typically span fifteen to twenty centimeters, sometimes past forty.
This terrapin is one of three subspecies of the pond slider, alongside the yellow-bellied and Cumberland sliders, and was once filed under Chrysemys. It used to be called Troost's turtle after the American herpetologist Gerard Troost, a name now attached to the Cumberland form. Its home range runs from southeastern Colorado to Virginia and Florida, in warm, still or slow water such as ponds, swamps and sluggish rivers, with logs and rocks for hauling out. Sunbathers often pile on top of one another, since, as ectotherms, they depend on outside heat.
The shell has a raised central row of vertebral scutes flanked by pleural scutes and edged by marginals notched at the rear. Partly webbed feet, head and tail all retract inside it. Females outgrow males, and most individuals live 20 to 30 years, some beyond 40. Juveniles are hard to sex, but adult males have longer front claws, which they use to grip during mating and to flutter against a female's face in courtship between March and July, as well as thicker tails with the vent farther back. Youngsters sometimes perform the courtship dance before maturing at about five.
Rather than truly hibernating, wild sliders brumate on pond bottoms from around October, when water drops below 10 degrees, surfacing now and then. They can go weeks without oxygen, running on glycolysis while heart rate and cardiac output fall by 80 percent, and minerals in the shell neutralise the resulting lactic acid.
It is the most traded turtle on Earth, and released pets now live on every continent except Antarctica, earning a place among the world's hundred worst invaders. Earlier maturity, more eggs and bigger bodies let them win basking spots, nests and food from native turtles, and they spread disease. Australia forbids the public to keep or trade them, the European Union bans imports, and Japan announced plans for a ban in 2015.
Source: Red-eared slider
