Occasionally, pet owners observe their yellow-bellied slider turtles eating or trying to eat the gravel in the bottom of the aquarium. This behavior can cause serious medical complications necessitating surgical removal of the stones in some cases. Though veterinarians and scientists have not reached a consensus regarding the reason for the behavior, they have proposed several hypotheses. The behavior may be a natural behavior to aid digestion, a way of obtaining minerals, a symptom of boredom or hunger.
Some animals -- most notably crocodilians and some birds -- consume rocks and stones purposefully. These stones reside in the digestive tract and help to crush and grind tough foods such as bone and seeds. It is possible that some turtles ingest rocks and stones for the same reason.
Turtles require significant amounts of calcium to build and maintain their bones and shell. Many captive food sources may be deficient in calcium and other necessary minerals. Mineral deficiencies can cause deformed shells, brittle bones and metabolic problems, any of which may cause your turtle to seek out sources of calcium and other minerals in his tank. The best way to avoid mineral deficiencies is by offering your turtle a varied and well-balanced diet. Use a high-quality vitamin and mineral supplement, and ensure that you are using proper, full-spectrum lighting so that your turtle can use the minerals in his diet.
In general, turtles are long-lived creatures who need mental stimulation. While not intelligent by mammalian standards, turtles are relatively smart reptiles and thrive better in complex environments than sterile, featureless habitats. Many animals eat when they are bored, and when a suitable food source is not available, they may try to eat unusual objects.
Habits of the Hungry
If you do not feed your yellow-bellied slider enough food, he may start looking at inorganic objects in the cage as food. Though rocks do not offer any calories for a hungry turtle, animals will go to great lengths to stave off hunger pains. Always be sure to feed your turtle enough food for his size, species and age, and be observant for strange behaviors such as eating unusual objects.
Avoiding the Issue
You can take several steps to eliminate the possibility that your yellow-bellied slider will consume gravel. The easiest solution is to avoid using gravel entirely, and instead use aquarium sand or no substrate at all. If you like, you can use gravel that is too large for your turtle to consume.
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