The red-eared turtle is the most popular domestic amphibian in the world, which is why it became the best-selling turtle at the end of the 20th century. This species is native to the southern United States and northern Mexico. However, it gradually began to spread to other regions, due to people’s refusal to keep it as a pet and throwing it into local water bodies.
Invasion and seizure of territories caused by imprudent human activities have led to problems with the fauna of many countries, as the red-eared turtle is crowding out native species. The redfin is included in the list published by the IUCN of the 100 most invasive species.
Origin of the species and description
Photo: Red-eared Tortoise
Fossils indicate that turtles first appeared on earth about 200 million years ago, during the Upper Triassic period. The first known tortoise was Proganochelys quenstedli. It had a fully developed shell, cranial skull and beak. But, Proganochelys had a few primitive features that modern turtles don’t have.
By the middle of the Jurassic, turtles had split into two main groups: arched-necked (pleurodire) and lateral-necked (cryptodires) turtles. Modern lateral-necked tortoises are found only in the southern hemisphere and tilt their heads to the side under the shell. Arched turtles retract their heads in an S shape. Scutemy was one of the first arched turtles.
Video: Red-eared turtle
The red-eared or yellow-bellied turtle (Trachemys scripta) is a freshwater turtle belonging to the Emydidae family. It takes its name from the small red stripe around its ears and from its ability to quickly glide off rocks and logs into the water. This species was previously known as Trost’s tortoise, after the American herpetologist Gerard Trost. Trachemys scripta troostii is now the scientific name for another subspecies, the Cumberland tortoise.
Trachemys scripta belongs to the order Testudines, which contains about 250 species.
Trachemys scripta itself contains three subspecies:
- T.s. elegans (red-eared);
- T.s. Scripta (yellow-bellied);
- T.s. troostii (Cumberland).
The first known literary mention of the red-eared bear dates back to 1553. When P. Cieza de Leone described them in the book “Chronicles of Peru”.
Appearance and Features
Photo: Red-eared turtle animal
The length of the shell of this species of turtles can reach 40 cm, but the average length ranges from 12.5 to 28 cm. Females are usually larger than males. Their shell is divided into two sections: the upper or dorsal carapace (carapace) + the lower, ventral (plastron).
The upper shell consists of:
- vertebral shields that form the central the elevated part;
- pleural shields located around the vertebral shields;
- marginal shields.
The scutes are bony keratin elements. The carapace is oval and flattened (especially in men). The color of the shell changes depending on the age of the turtle. The carapace usually has a dark green background with light or dark markings. In young or newly hatched individuals, this is a green foliage color that gradually darkens in maturing specimens. Until it turns dark green, then changes hue between brown and olive green.
The plastron is always light yellow with dark, paired, irregular markings in the center of the shields. The head, legs and tail are green with thin, irregularly shaped yellow lines. The entire shell is covered in stripes and markings to aid in camouflage.
An interesting fact! The animal is a poikilotherm, that is, it cannot independently regulate its body temperature and is completely dependent on the ambient temperature. For this reason, they need to sunbathe frequently to keep warm and maintain their body temperature.
Turtles have a complete skeletal system with partially webbed feet to help them swim. The red stripe on each side of the head made the red-eared turtle stand out from other species and became part of the name, as the stripe is located behind the eyes, where their (outer) ears should be.
These stripes may lose their color over time. Some individuals may have a small marking of the same color on the top of their heads. In addition, they do not have a visible external ear or external auditory meatus. Instead, there is a middle ear completely covered by a cartilaginous tympanic disc.
Where does the red-eared slider live?
Photo: Little Red-eared Turtle
Habitats are found in the Mississippi River region and the Gulf of Mexico, as well as in warm climates in the southeastern United States. Their home territories range from southeastern Colorado to Virginia and Florida. In nature, red-eared turtles inhabit areas with sources of calm, warm water: ponds, lakes, swamps, streams and slow-moving rivers.
They live where they can easily get out of the water, climb rocks or tree trunks to warm up in the sun. Often sunbathe in a group or even on top of each other. These turtles in the wild always stay close to water unless they are looking for a new habitat or laying eggs.
Due to their popularity as pets, redworts have been released or escaped into the wild in many parts of the world. Now wild populations are found in Australia, Europe, Great Britain, South Africa, the Caribbean, Israel, Bahrain, the Marianas, Guam, as well as in Southeast and Far East Asia.
An invasive species has a negative impact on the ecosystems it occupies because it has certain advantages over native inhabitants, such as lower age at maturity, higher fertility rates. They transmit diseases and outcompete other turtle species with which they compete for food and breeding space.
What does the red-eared turtle eat?
Photo: Red-eared turtle boy
The red-eared slider has an omnivorous diet. They need abundant aquatic vegetation, as this is the main food of adults. Turtles do not have teeth, but instead have serrated and sharp horny ridges on their upper and lower jaws.
The menu of the animal includes:
- aquatic insects;
- worms;
- crickets;
- snails;
- small fish,
- frog eggs,
- tadpoles ,
- water snakes,
- various algae.
Adults tend to be more herbivorous than juveniles. In its youth, the red-eared turtle is a predator, feeding on insects, worms, tadpoles, small fish and even carrion. Adults are more inclined towards a vegetarian diet, but will not refuse meat if they can get it.
Curious fact! Sex in turtles is determined during the embryogenesis phase and depends on the incubation temperature. These reptiles lack the sex chromosomes that determine sex. Eggs that are incubated at t 22 — 27°C become only males, while eggs that are incubated at higher temperatures become females.
These reptiles are highly adaptable to their environment and can adapt to anything from brackish waters to artificial canals and city ponds. The red-eared turtle can wander away from water and survive cold winters. Once an available habitat is found, the species quickly colonizes the new area.
Character and lifestyle features
Photo: Great red-eared turtle
Red-eared turtles live from 20 to 30 years, but can live for more than 40 years. The quality of their habitat has a strong impact on longevity and well-being. Turtles spend most of their time in the water, but because they are cold-blooded reptiles, they leave the water to sunbathe to regulate their body temperature. They absorb heat more effectively when the limbs are extended outward.
Redworts do not hibernate, but plunge into a kind of suspended animation. When turtles become less active, they sometimes come up to the surface for food or air. In the wild, turtles hibernate at the bottom of ponds or shallow lakes. As a rule, they become inactive in October, when the temperature drops below 10 °C.
During this time, the turtles go into a stupor state, during which they do not eat or defecate, remain almost motionless, and their breathing rate drops. Individuals are more often underwater, but have also been found under rocks, in hollow stumps, and in sloping banks. In warmer climates, they can become active in winter and come to the surface to swim. When the temperature starts to drop, they quickly return to the stupor state.
Note! Red-eared turtles are harvested for food from early March to late April.
When brumated, the species can survive anaerobically (without air intake) for several weeks. Turtles’ metabolic rate drops sharply during this time, and heart rate and cardiac output are reduced by 80% to minimize energy requirements.
Social structure and reproduction
Photo: Red-eared Turtle
Male tortoises reach sexual maturity when their carapace diameter reaches 10 cm, and females become mature when their carapace is 15 cm. Both males and females are ready to reproduce at five to six years of age. The male is smaller than the female, although this parameter is sometimes difficult to apply because the compared individuals may be of different ages.
Courtship and mating takes place underwater from March to July. During courtship, the male swims around the female, directing his pheromones towards her. The female begins to swim towards the male and, if she is receptive, sinks to the bottom to mate. Courtship lasts somewhere around 45 minutes, but mating takes only 10 minutes.
The female lays between two and 30 eggs depending on body size and other factors. Moreover, one individual can lay up to five clutches in one year, with time intervals of 12-36 days.
Interesting fact! Fertilization of the egg occurs during oviposition. This process allows fertilized eggs to be laid in the next season, as sperm remains viable and available in the female’s body even in the absence of mating.
In the last weeks of pregnancy, the female spends less time in the water and looking for a suitable place to lay eggs. She digs a nest hole using her hind legs.
Incubation takes from 59 to 112 days. The offspring remain inside the egg shell after hatching for two days. For the first few days, the young still feed from the yolk sac, the supply of which still remains in the egg. The area through which the yolk is absorbed must heal on its own before the turtles can swim. The time between hatching and submersion is 21 days.
Natural enemies of the red-eared turtle
Photo: Adult red-eared turtle
Due to its size, bite and shell thickness, adult red-eared turtles should not be afraid of predators, of course, if there are no alligators or crocodiles nearby. She can retract her head and limbs into her shell when threatened. In addition, redfins watch for predators and seek refuge in the water at the first sign of danger.
However, this does not apply to juveniles, which are preyed upon by various predators, including:
- raccoons;
- skunks;
- foxes;
- wading birds;
- storks.
Raccoon, skunk and fox also steal eggs from this species of turtle. Juveniles have an unusual defense against predatory fish. When swallowed whole, they hold their breath and chew on the mucous membrane inside the fish until they are regurgitated by the fish. The bright colors of small predators warn large fish to avoid them.
In their home range, red-eared sliders occupy an important ecological niche both as food and as a predator. Outside their habitats, they fill the same types of niches and become an important food source for predators in urban and suburban areas.
Because of their adaptability, red-eared tortoises are the predominant tortoise species in urban environments. Most parks in many cities in the United States have thriving colonies of red-eared turtles for people to enjoy.
Population and Species Status
Photo: Red-eared turtle
The red-eared turtle is listed by the International Union for Conservation of Nature (IUCN) as “one of the world’s worst invasive alien species”. It is considered an environmental pest outside its natural range because it competes with native turtles for food, nesting sites, and swimming spots.
Note! Red-eared turtles are recognized as reservoirs in which Salmonella bacteria can be stored for a long time. Infection of humans caused by improper handling of turtles has led to a restriction of its sales.
The red-eared slider has been exploited by the livestock industry since the 1970s. Huge numbers have been produced by turtle farms in the US for the international pet trade. Red-eared slider turtles have become popular pets due to their small size, low nutritional requirements, and reasonable price.
They are often given as pet gifts when they are very small and attractive. However, the animals quickly grow into large adults and are capable of biting their owners, resulting in them being abandoned and released into the wild. Therefore, they are now found in freshwater ecosystems in many developed countries.
Baby red-eared sliders were smuggled into and illegally released in Australia. Now, in some parts of the country, wild populations are found in many urban and semi-rural areas. Officially recognized in Australia as a pest that eliminates the local endemic reptofauna.
Their import has been banned by the European Union, as well as by certain countries — EU members. The red-eared tortoise will be banned from imports to and from Japan, this law will come into force in 2020.
