Blue-tongued skinks are named for the prominent blue coloration of their tongue. But what makes them blue? Less than 1% of the animal kingdom is thought to have any true blue pigment. One of the only vertebrates known to contain blue pigment is the blue poison dart frog (Dendrobates tinctorius azureus). In other animals, blue coloration is achieved by structures that change the wavelength of light. A blue-tongued skink’s tongue reflects UV-blue light, so our eyes, and the eyes of most other anim