The red-eared slider or red-eared terrapin ( Trachemys scripta elegans) is a subspecies of the pond slider ( Trachemys scripta), a semiaquatic turtle belonging to the family Emydidae. Native to the southern United States and extreme northern Mexico, it is popular as a pet across the world, and is the most Invasive species turtle. It is the most commonly traded turtle in the world.
The red-eared slider is native to the Midwestern United States and northern Mexico, but has become established in other places because of pet releases, and has become invasive in many areas where it outcompetes native species. The red-eared slider is included in the list of the world's 100 most invasive species.
The shell is divided into the upper or dorsal carapace, and the lower, ventral carapace or plastron. The upper carapace consists of the vertebral scutes, which form the central, elevated portion; pleural scutes that are located around the vertebral scutes; and then the marginal scutes around the edge of the carapace. The rear marginal scutes are notched. The scutes are bony elements. The carapace is oval and flattened (especially in the male) and has a weak keel that is more pronounced in the young. The color of the carapace changes depending on the age of the turtle. It usually has a dark green background with light and dark, highly variable markings. In young or recently hatched turtles, it is leaf green and gets slightly darker as a turtle gets older, until it is a very dark green, and then turns a shade between brown and olive green. The plastron is always a light yellow with dark, paired, irregular markings in the centre of most scutes. The plastron is highly variable in pattern. The head, legs, and tail are green with fine, irregular, yellow lines. The whole shell is covered in these stripes and markings that aid in Mimicry an individual.
turtles also have a complete Skeleton, with partially webbed feet that help them to swim and that can be withdrawn inside the carapace along with the head and tail. The red stripe on each side of the head distinguishes the red-eared slider from all other North American species and gives this species its name, as the stripe is located behind the , where their (external) ears would be. These stripes may lose their color over time. Color and vibrance of ear stripe can indicate immune health, with bright red having higher immune response than yellow stripes. Some individuals can also have a small mark of the same color on the top of their heads. The red-eared slider does not have a visible outer ear or an external auditory canal; instead, it relies on a middle ear entirely covered by a cartilaginous tympanic disc.
Like other turtles, the species is poikilotherm and thus dependent on the temperature of its environment. For this reason, it needs to sunbathe frequently to warm up and maintain body temperature.
Red-eared slider young look practically identical regardless of their sex, making distinguishing them difficult. One useful method, however, is to inspect the markings under their carapace, which fade as the turtles age. Distinguishing the sex of adults is much easier, as the shells of mature males are smaller than those of females. Male red-eared sliders reach sexual maturity when their carapaces' diameters measure and females reach maturity when their carapaces measure about . Both males and females reach sexual maturity at 5–6 years old. Males are normally smaller than females, although this parameter is sometimes difficult to apply, as individuals being compared could be of different ages.
Males have longer on their front feet than the females; this helps them to hold onto a female during mating, and is used during courtship displays.
They live in areas of calm water, where they are able to leave the water easily by climbing onto rocks or tree trunks so they can warm up in the sun. Individuals are often found sunbathing in a group or even on top of each other. They also require abundant aquatic plants, as these are the adults' main food, although they are omnivores. They are, however, carnivorous as juveniles as they require a high protein intake for growth.Turtles in the wild always remain close to water unless they are searching for a new habitat or when females leave the water to lay their .
Owing to their popularity as pets, red-eared sliders have been released or escaped into the wild in many parts of the world. This turtle is considered one of the world's worst invasive species. Today, they can be found on six out of seven continents (everywhere except for Antartica). Feral populations are now found in Bermuda, Canada, Australia, Europe, Great Britain, South Africa, the Caribbean Islands, Israel, Bahrain, the Mariana Islands, Guam, Russia, and Southeast Asia and far-east Asia. Within Great Britain, red-eared sliders have a wide distribution throughout England, Scotland, and Wales. In Spain, the red-eared slider is in direct competition with Mauremys leprosa for food and basking spots. The red-eared slider has a certain advantage over M. leprosa.
In Australia, it is illegal for members of the public to import, keep, trade, or release red-eared sliders, as they are regarded as an invasive species – see below. Their import has also been banned by the European Union as well as specific EU member countries.
During brumation, T. s. elegans can survive anaerobically for weeks, producing ATP from glycolysis. The turtle's metabolic rate drops dramatically, with heart rate and cardiac output dropping by 80% to minimize energy requirements.
On occasion, a male may appear to be courting another male, and when kept in captivity may also show this behaviour towards other household pets. Between male turtles, it could be a sign of dominance and may preclude a fight. Young turtles may carry out the courtship dance before they reach sexual maturity at 5 years of age, but they are unable to mate. mating, the female spends extra time basking to keep her eggs warm. She may also have a change of diet, eating only certain foods, or not eating as much as she normally would. A female can lay between two and 30 eggs depending on body size and other factors. One female can lay up to 5 clutches in the same year, and clutches are usually spaced 12–36 days apart. The time between mating and egg-laying can be days or weeks. The fertilization and laying can also be in conjunction, with eggs immediately laid based on location and nutrients available. The actual egg fertilization takes place during the egg-laying. This process also permits the laying of fertile Egg cell the following season, as the sperm can remain viable and available in the female's body in the absence of mating. During the last weeks of gestation, the female spends less time in the water and smells and scratches at the ground, indicating she is searching for a suitable place to lay her eggs. The female excavates a hole, using her hind legs, and lays her eggs in it.
Incubation takes 59–112 days. Late-season hatchlings may spend the winter in the nest and emerge when the weather warms in the spring. Just prior to hatching, the egg contains 50% turtle and 50% egg sac. A new hatchling breaks open its egg with its egg tooth, which falls out about an hour after hatching. This egg tooth never grows back. Hatchlings may stay inside their eggshells after hatching for the first day or two. If they are forced to leave the eggshell before they are ready, they will return if possible. When a hatchling decides to leave the shell, it still has a small sac protruding from its plastron. The yolk sac is vital and provides nourishment while visible, and several days later, it will have been absorbed into the turtle's belly. The sac must be absorbed, and does not fall off. The split must heal on its own before the turtle is able to swim. The time between the egg hatching and water entry is 21 days.
to or inordinate motion of the protruding egg yolk – enough to allow air into the turtle's body – results in death. This is the main reason for marking the top of turtle eggs if their relocation is required for any reason. An egg turned upside down will eventually terminate the embryo's growth by the sac smothering the embryo. If it manages to reach term, the turtle will try to flip over with the yolk sac, which would allow air into the body cavity and cause death. The other fatal danger is water getting into the body cavity before the sac is absorbed completely, and while the opening has not completely healed yet.
The sex of red-eared sliders is determined by the incubation temperature during critical phases of the embryos' development. This is a phenomenon known as temperature-dependent sex determination. Only males are produced when eggs are incubated at temperatures of , whereas females develop at warmer temperatures. Washington NatureMapping Program, Animal Facts: Red-eared Slider. Retrieved: 2012-11-13. Colder temperatures result in the death of the embryos.
Red-eared slider turtles are considered a significant threat to native turtle species; they mature more quickly, grow larger, produce more offspring, and are more aggressive. Numerous studies indicate that red-eared slider turtles can out-compete native turtles for food and nesting and basking sites. Unlike the general diet of pet red-eared sliders, wild red-eared sliders are usually omnivorous. Because red-eared slider turtles eat plants as well as animals, they could also have a negative impact on a range of native aquatic species, including rare frogs. Also, a significant risk exists that red-eared slider turtles can transfer diseases and parasites to native reptile species. A malaria-like parasite was spread to two wild turtle populations in Lane Cove River, Sydney.
Social and economic costs are also likely to be substantial. The Queensland government has invested close to AU$1 million in eradication programs to date. The turtle may also cause significant public-health costs due to the impacts of turtle-associated salmonella on human health. Outbreaks in multiple states and fatalities in children, associated with handling Salmonella-infected turtles, have been recorded in the US. Salmonella can also spread to humans when turtles contaminate drinking water.
The actions by state governments have varied considerably to date, ranging from ongoing eradication efforts by the Queensland government to very little action by the government of New South Wales. Experts have ranked the species as high priority for management in Australia, and are calling for a national prevention and eradication strategy, including a concerted education and compliance program to stop the illegal trade, possession, and release of slider turtles.
As pets, invasive species, and human infection risk
Infection risks and United States federal regulations on commercial distribution
US state laws
Invasive status in Australia
Invasive status in India
In popular culture
See also
Further reading
External links
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