Red-eared Slider

About the red-eared slider

The red-eared slider, or red-eared terrapin, is a subspecies of the pond slider (Trachemys scripta), a terrapin in the family Emydidae. It's native to the central and southern United States and northern Mexico, but its popularity as a pet has carried it around the world, and it's now considered the most invasive chelonian and the most commonly traded turtle on earth. Its name comes from a small red stripe near where its ears would be, along with its habit of sliding quickly off rocks and logs into the water.

The carapace can reach over 40 cm (16 in) in length, though typical adults run 15 to 20 cm (6–8 in), with females usually larger than males. The upper shell is oval and somewhat flattened, especially in males, with a weak keel more pronounced in young turtles. Coloring shifts with age: hatchlings and young turtles show a leaf-green carapace that darkens over time to very dark green and eventually a shade between brown and olive green, marked with variable light and dark patterns. The plastron stays a light yellow with dark, irregular markings at the center of most scutes. The head, legs, and tail are green with fine yellow lines, and partially webbed feet help the turtle swim; like the head and tail, the legs can be withdrawn into the shell. As with other chelonians, the species is poikilothermic and must bask frequently in the sun to regulate its body temperature.

Males and females differ in several ways beyond size. Male red-eared sliders reach sexual maturity at a carapace diameter of about 10 cm (3.9 in), females at about 15 cm (5.9 in), with both sexes typically maturing at 5 to 6 years old. Males have longer front claws, used to grip a female during mating and in courtship displays, along with thicker, longer tails and a slightly concave plastron that helps stabilize them during mating; the female's plastron stays flat. Older males can develop a dark, greyish-olive melanistic coloring that obscures their markings and their trademark red ear stripe, while a female's appearance stays largely the same throughout her life.

Behavior and diet

Red-eared sliders are almost entirely aquatic but leave the water regularly to bask, often piling on top of each other on logs or rocks in the sun. As adults, they're mainly herbivorous, relying heavily on aquatic plants, though juveniles need a high-protein diet for growth and are largely carnivorous at that stage; overall the species is considered omnivorous.

Rather than truly hibernating, red-eared sliders brumate: they become far less active over winter but occasionally rise for food or air. In the wild, brumation happens at the bottom of ponds or shallow lakes, usually beginning in October once temperatures drop below 10 °C (50 °F); breathing and eating both slow or stop almost entirely during this state, and the turtles typically resurface to feed and bask from early March into April. Metabolically, brumating sliders can survive anaerobically for weeks, with heart rate and cardiac output both dropping by roughly 80% to conserve energy.

Courtship and mating happen underwater, mainly between March and July. A male swims around a female, fluttering the long claws on his front feet near her face, and if she's receptive she sinks to the bottom to mate; courtship can last 45 minutes, though mating itself takes about 10. A female may lay 2 to 30 eggs per clutch and up to five clutches a year, spaced 12 to 36 days apart, in a hole she digs with her hind legs. Incubation takes 59 to 112 days, and the sex of hatchlings is determined by incubation temperature — eggs kept at 22–27 °C (72–81 °F) produce only males, while warmer temperatures produce females.

Range and habitat

The red-eared slider originated around the Mississippi River and the Gulf of Mexico, ranging natively from the southeast of Colorado to Virginia and Florida in warm parts of the southeastern United States. In the wild it favors calm, still water such as ponds, lakes, swamps, creeks, streams, and slow-moving rivers, and it can also tolerate brackish water; it needs easy access to basking spots such as rocks and logs, plus abundant aquatic plants for food.

Because of its popularity as a pet, the species has been released or has escaped into the wild across much of the world, and it's now found on six of the seven continents. It's considered one of the world's worst invasive species, outcompeting native turtles for basking and nesting sites and food, transmitting disease, and displacing other chelonians. Its import, trade, and release are now restricted or banned in places including Australia, the European Union, and, since 2023, Japan.

Conservation status

The red-eared slider is a subspecies of the pond slider, Trachemys scripta, and the IUCN assesses it at the species level. The pond slider is rated Least Concern on the IUCN Red List, in an assessment published in 2011.

Rather than facing conservation threats itself, the red-eared slider is better known as a conservation problem for others. It is listed among the world's 100 most invasive species, and feral populations established through pet releases and escapes now compete with native turtles across much of the globe, including in Great Britain, Australia, continental Europe, South Africa, and parts of Asia.

In the United States, its trade has also been shaped by public-health rules rather than conservation ones. A 1975 FDA regulation restricts the commercial sale of small turtles because reptiles can carry Salmonella without symptoms, and handling them has caused documented human infections.