Red-eared sliders, named for the red stripe behind the ear, are a popular pet turtle species, and they can live up to 50 years in the wild. Understandably, these long-living reptiles are sometimes rehomed, and it can be challenging to determine how old they are when you don't know when they were hatched.
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There are clues, however, that can help you guess the approximate age of your turtle, including the size of his carapace and the number of rings on the shell. Knowing the sex of your turtle is helpful because females are visibly larger than males and are sometimes identified as older than they really are.
Size of adult red-eared sliders
Determining the point when a red-eared slider is an adult isn't an exact science. However, most reptiles are considered adults at sexual maturity, which for turtles takes longer than you might think. If your female turtle is between 6 and 8 inches long, she is likely 5 to 7 years old and is considered an adult. If your male red-eared slider is 4 inches long, he's between 3 and 5 years old and has likely reached sexual maturity.
The shell of a female red-eared slider grows to between 10 and 12 inches long, and a male grows no more than 8 inches long. If your turtles are this length, you know they are adults and are at least 3 to 5 years old. Clearly, knowing the gender of the turtle is helpful when determining age.
Determining adult red-eared slider age
Knowing whether you have an old red-eared slider is challenging but not impossible. After two years, the namesake red line beside the ear becomes darker, and the shell takes on a darker hue. Chips and discoloration of the shell are usually signs of aging but can also be evidence of one bad fall out of the tank.
Food intake, either too much or too little, creates rings on the turtle's shell, also called a carapace. Usually, the rings form twice a year because turtles generally go through two natural feast and famine cycles. So, counting rings and then dividing by two can give you some idea of the turtle's age. However, older turtles can have rings that are very close together, resulting in counting errors. Rings are still an estimate.
Claws on male turtles can also give you a clue to the turtle's age. Claws on a male red-eared slider grow significantly by the time he is 2 years old and are much bigger than female claws. Two to 3-year-old turtles have prickly, sharp claws, but as the turtle ages, the claws become shorter and blunter. Worn claws are a sign of advanced age.
Life span of captive red-eared sliders
While wild red-eared sliders can live up to five decades, most captive turtles live between 20 and 30 years with good care. Unfortunately, many red-eared slider pets get sick or die because of unintentional poor care, resulting in problems such as shell rot and skin ulcers. Turtle maintenance is time-consuming.
Clean tanks regularly and use a water filter capable of cleaning a tank five times the size of the turtle's enclosure. Dirty tanks and lack of heat are typical causes of shell rot and skin ulcers. Like most reptiles, turtles require calcium supplements and regular exposure to sunlight — specifically, ultraviolet B light is needed for indoor pet turtles.
Rehoming a red-eared slider
Red-eared sliders are popular reptile pets, but they require commitment and diligent care. If you find that you can no longer care for a pet with a potential longevity of two or more decades, do not release her into the wild. Red-eared sliders are one of the most invasive species in North America for this reason. Instead, contact a local reptile zoo, rescue, or animal control service near you to responsibly surrender your turtle.