This article is a condensation from the talk given by Dr. Robin Scott, DVM at a meeting of the Gulf Coast Turtle & Tortoise Society.
Dr. Scott's talk was about the proper feeding of chelonians and diseases associated with poor nutrition. She began her talk by defining the three general categories of chelonians and noting the diet each group generally follows: Tortoises - herbivore (eat plant material) Box Turtles - omnivore (eat any-and-everything, half plant material and half meat) Water Turtles - carnivore (eat meat)
All turtles and tortoises need a proper ratio of calcium and phosphorus in their diets, but in captivity, this ratio is difficult to maintain. Many animals fall into ill health due to an improper ratio of these minerals. The culprit is almost always a poor diet.
A normal mineral balance in a turtle's body would be two parts calcium for each one part phosphorus. that means that for every two molecules of calcium floating through the animals bloodstream, there would be one molecule of phosphorus. But often, proportions get out of whack and an overabundance of phosphorus develops. When the body recognizes this, it tries to regain its correct balance. The body starts stealing calcium from the animal's bones to put calcium into the bloodstream. The bones actually self-destruct in order to provide the body with the calcium it needs.