The Calrissian Chameleon is a small reptilianoid creature whose external appearance is virtually identical to that of an Earth chameleon. It also shares the Earth chameleons' ability of changing colors to match the environment. A Calrissian Chameleon's pituitary gland is similar enough to that of a Beagle to allow for medical transplants between the two. It secretes a rare toxin that is very useful for treating respiratory infections.
A Calrissian Chameleon was one of the many live organisms kept by Doctor Phlox in his sickbay, until it had to be killed in order to have its pituitary gland transplanted to the captain's dog, Porthos, thus saving the dog's life.