The horses are called Direhorses, known as Pa'li by the Na'vi. The direhorse (as with most over native creatures of Pandora) has two long, thin antennae (called a neural whip by humans) that emerge from either side of the top of the skull. These appendages have feathery tips covered in tiny cilia which undulate constantly, and seek out the antennae of other direhorses as they move near. Xenobiologists believe that the touch of antennas is for pleasure and affection, but also a means of transferring information about food sources and potential dangers; herds often move in unison shortly after touching antennae.
The animals are easily startled, and, when all six legs are working in unison, can reach ninety-five kilometers per hour. The direhorse is larger by a third than the largest Terran draft horses such as the Shire, Clydesdale or the Percheron, and substantially larger than the biggest horse ever recorded on Earth. The Na'vi are excellent riders and the direhorse, with its six legs, is a swift, nimble mount that is well-adapted to the rugged Pandoran terrain. The Direhorse is a land omnivore that uses its long snout, as well as its long giraffe-like tongue, to feed on sap. It is able to capture some protein intake through insects trapped inside the sap.
The Thanator, known as Palulukan in the Na'vi language, is much more fierce creature and is one of the most if not THE most aggressive predator in the Pandoran jungles. Its musculature is pronounced and impressive, providing power for protracted runs and leaps. The speed of its neck and jaw strike is swift. In addition to conventional ripping and tearing, the Thanator can also deliver a lethal blow from its armored tail. The Thanator's senses are so highly developed that, depending on atmospheric conditions, it can detect prey up to thirteen kilometers away.
The Thanator has ten sensory quills that sprout from sections of armor plating that encircle the rear of its skull. The function of the quills is still a mystery, but it has been hypothesized that they may be tied to an internal mechanism of prey location. The quills also flare up and produce a more menacing appearance.
It also has an armored neck and back, a massive distensible jaw, and twenty-three centimeter long sharp teeth. The Thanator has burnished black skin. Its ten external sensory quills are colored bright red and yellow. The upper lip folds back for maximum tooth extension. The Na'vi, who are around 9 to 10 feet (3 meters) tall, could ride on the back of one of these beasts, making them approximately 20 feet (6 meters) long.