The ear — lateral surface
|Part of||External ear|
The tragus is a small pointed eminence of the external ear, situated in front of the concha, and projecting backward over the meatus. It also is the name of hair growing at the entrance of the ear. Its name comes from Ancient Greek tragos, meaning 'goat', and is descriptive of its general covering on its under surface with a tuft of hair, resembling a goat's beard. The nearby antitragus projects forwards and upwards.
Because the tragus faces rearwards, it aids in collecting sounds from behind. These sounds are delayed more than sounds arriving from the front, assisting the brain to sense front vs. rear sound sources.
The tragus is a key feature in many bat species. As a piece of skin in front of the ear canal, it plays an important role in directing sounds into the ear for prey location and navigation via echolocation. Because the tragus tends to be prominent in bats, it is an important feature in identifying bats to species. The tragus allows echolocating bat species to vertically discriminate the objects around them, which is key to identifying where prey items and obstacles are in three-dimensional space. In studies where an individual's tragi are temporarily glued out of their normal positions, the bat's navigational acuity is four times worse than individuals with unmodified tragi. Based on this study, the authors concluded that the tragus's function is to create acoustic cues to determine the direction of a target in the vertical plane. Not all echolocating bats possess a tragus, however. Horseshoe bats are one such family; it is thought that the way in which the outer bottom edge of the ear folds in on itself functions in a similar way to the tragus in other families.
The long tragus of the brown long-eared bat
The curved tragus of the eastern red bat
The blunt tragus of the spotted bat
- "Why do older men have hair growing in their noses and ears?" from The Straight Dope
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