Turtles (and all reptiles) need UVB light to produce Vitamin D3 and to help them properly use calcium and other nutrients. Without enough UVB light, turtles will experience shell problems and metabolic bone disease. If they are deprived of UVB light for too long a time, they will die. So please be sure that you can afford to buy a UVB lamp and replace it every six months or so before you get your turtle.