The operculum is a nostril-like opening on many Pandoran animals. The operculum's openings are placed in two rows, one on each side of the animal's neck. Many openings are in one row, allowing for maximum air intake. This can be seen clearly when Jake Sully is learning to ride and make tsaheylu with Pale, a direhorse. The more simian-like species on Pandora, such as the prolemuris and Na'vi, lack them and breathe like animals from Earth.