What Are Tortoise Shell Rings For?

The rings on the shell of a tortoise are called "growth rings." They surround the bumps or "scutes" on the tortoise's shell. As it sheds its scutes, growth rings are formed. If a tortoise is not fed the proper diet or growth occurs too quickly, the rings will become raised, known as "pyramiding." Sufficient amounts of vitamins and minerals are required for healthy shell growth. Some believe the age of a tortoise can be revealed by counting its growth rings.

  1. Growth Rings and Age

    • Counting the growth rings of a tortoise when it is young may reveal its age. However, as it matures, it is nearly impossible to accurately ascertain its true age by counting the growth rings around its scutes. According to Michael J. Connor of the California Turtle &Tortoise Club, "These rings are formed because the scutes (or shields) are a modified form of skin that is continually renewed. The new scute material grows under the old, and being larger shows at the edges of the scute as a 'ring.' Unlike trees, however, tortoises (especially well-nourished captives) don't get a new 'growth ring' every year. On the contrary, several 'growth rings' may appear in a single season."

    What to Feed

    • Feeding a tortoise the appropriate foods will ensure healthy shell growth. A balanced diet is composed of 50 percent plants and vegetables, 25 percent proteins and 25 percent commercial food preparations for tortoises. Offer watercress, collards, red and green leaf lettuce, romaine lettuce, endive, red clover, carrot tops, wax beans, green beans, okra, carrots, squash, sweet potatoes, bell peppers, dandelions, carnations, pansies and hibiscus. Proteins can include mealworms, silkworms, earthworms, snails, slugs and crickets. Fruit should be fed in moderation and offered only as an occasional treat. Provide grapes, blackberries, strawberries, apples, mangoes, kiwis, blueberries, figs, tomatoes and cantaloupes.

    Foods to Avoid

    • Plants high in protein can cause soft shells in young tortoises and premature growth due to the high phosphorus-to-calcium ratio. High-protein plants include sweet corn, bean sprouts and peas. Plants toxic to tortoises are columbine, ragwort, spurge, daffodil and hellebore. Do not feed iceberg lettuce, spinach, kale, sorrel, banana or unnatural foods such as cat and dog food. Evidence of an unhealthy diet is revealed in a soft shell, pyramiding, excessive shedding of skin, lethargy and lack of appetite. The result can be a decrease in liver and kidney function and metabolic bone disease.

    Vitamins and Minerals

    • Adequate amounts of calcium are essential to a tortoise's growth and the overall health of its shell and bones. Purchase reptile calcium, vitamin D3 and cuttlefish bone from a pet store. Sprinkle calcium and vitamin D3 powder over the tortoise's food. Vitamin D3 is required for adequate calcium absorption. Cuttlefish bone provides an additional calcium source and trims a tortoise's beak. Do not use calcium supplements which include phosphorous, as it prevents proper absorption of calcium into the bones.