If you can get over the whole spitting thing, camels are pretty cute—at least until they open up their mouths. It's like staring into the Sarlacc pit from Return of the Jedi. What are those little fleshy things? What purpose do they serve? What is going on here?
The things in the camel's mouth are oral papillae, and they're totally normal, says Luis Padilla, Director of Animal Health at the St. Louis Zoo. "Papillae are projections or raised structures found in different parts of the mouth, internal cheeks, and tongues of some species," he says. "There are many kinds of papillae. Most have simply a mechanical function, but some have a sensory function, either positional sensation or they may have taste buds on them. In ruminants, the ones on the cheek and esophagus can be extremely large, as what you see in the picture."
When the papillae's function is purely mechanical, Padilla says, they're usually cone- or triangular-shaped, and work in conjunction with the tongue and the muscles of the mouth to help manipulate food in one direction, typically toward the stomach (which means that a camel's mouth has more in common with the Sarlacc pit than just looks!). Camels need those big papillae because of what they're eating. "Swallowing chewed leaves and sticks without some sort of mechanical assistance can be hard," Padilla says. "The papillae are sort of firm—they can be partially keratinized—and can feel almost like plastic. In the areas where they are keratinized, the papillae protect the cheek and mouth from getting scratched, abraded, poked, perforated, or injured." Though all camelids have papillae, size and shape can vary, and they can be affected by the animals' health, according to Padilla. "Blunting of the papillae or ulcerated papillae are signs of certain disease conditions," he says.
Many different kinds of animals have papillae, including humans. "There are lots of tiny papillae in the human mouth, especially on the tongue," Padilla says. "Humans and most primates do not have papillae as big as camels’ or other ruminants’. Because of our masticatory adaptations and diet, we don’t really need them to keep food flowing in one direction on the lining of our cheek or esophagus." (Also important to note: "Taste buds sit on top of a specialized kind of papilla," Padilla says, "but not all papillae are taste buds.")
But look inside the mouths of many fish-eating birds, reptiles, and fish, and you'll find varying types of papillae. "There are actually about 10 to 15 types of papillae based on their shape, location, and function," Padilla says. "These papillae are so large and elaborate in some species—like penguins or sea turtles—that once you put something in their throat, it can be sort of difficult to pull it back." And they're not just found in the mouth; Padilla says papillae can be found in some other parts of the gastrointestinal system, including the stomach, esophagus, and rumen of certain species; depending on the animal, and the location of the papillae, proportions and firmness vary. Sea turtles, for example, have pretty soft papillae.
Back to camels, though—there's one more thing Padilla wants to point out about that mouth. "In some of the photos [on the Internet], you see the really impressive canine teeth of some male camels," he says. "These can be pretty dangerous."
Photo courtesy of Flickr user AnneLeroy; used with permission.