Lemur behavior is as variable as lemur morphology. Some lemur species have extensive vocal repertoires, including the ring-tailed lemur and ruffed lemurs. Lemurs range in weight from the mouse lemur to the indri. The Philippine flying lemur is endemic to the southern Philippines. They are Appa, Aang's six-legged flying bison, and Momo, his flying pet lemur. Olfactory communication is critically important for strepsirrhines like the ring-tailed lemur. The ring-tailed lemur is a relatively large lemur. Durrell is the home to six species of lemur. The clitoral morphology of the ring-tailed lemur is the most well-studied. The greatest concern facing lemur populations is habitat destruction and degradation. Finally, Zoboo turns back into a normal lemur and returns to his home in Madagascar. The eyes of the ring-tailed lemur contain one cone to five rods. In some strepsirrhines, such as the red-bellied lemur, scent glands occur atop the head. The creature appeared superficially similar to a modern lemur. The average lifespan of the Philippine flying lemur is unknown.