Tortoises have excellent color vision. In addition to the colors that humans observe, they also see into the ultraviolet spectrum according to Ronald Orenstein, author of Turtles, Tortoises and Terrapins: Survivors in Armour. Because of this wonderful gift, people need to be careful when interacting with tortoises. I have heard of tortoises mistaking painted toenails for a piece of fruit. My friend told me how the tortoise she grew up with, Tommy, used to chase her when she wore flip flops. As a veterinarian, I always wear clear nail polish for this very reason. I don’t want a reptile to confuse my finger with a berry.