![]() ![]() This dense fibrous mass measured to be about 37-57 µm in width and 8.5-11 µm in thickness among the owls utilized for this study. The basilar membrane is relatively thin toward the distal end of the papilla, but has a thick fibrous mass toward the proximal end. The vestibular surface of the basilar membrane is covered by supporting cells and a few border cells at the inferior edge of the membrane. Two major parts that construct the basilar membrane of the barn owl include the vestibular part and the tympanic part. The distal tip of the papilla is occupied exclusively by tall hair cells, whereas the proximal tip is occupied exclusively by lenticular cells. Tall hair cells are only present on the distal half of the owl’s papilla, starting at about 5 mm from the proximal end, along with some short-haired cells. Proximal sensory hair cells contained mostly short hair cells along with a few intermediate hair cells, but absolutely no tall hair cells. The basilar papilla of the cochlea was measured to be 9.5-11.5 mm long. The cochlear duct of the owl contains the basilar papilla, the tectorial membrane, the tegmentum vasculum, and the macula of the lagena. This study revealed that the basilar papilla of barn owls has two unique features being a proliferation of lenticular cells and a thickening of the basilar membrane. ![]() The temporal lobes of the owls were then removed from the skulls, post-fixed in 1% osmium tetroxide, dehydrated, then embedded in Araldite to study the anatomy of the inner ear. The anatomy of the inner ear in barn owls was studied in an experiment where three owls were utilized and fixed at laboratories by the intravascular perfusion of 1% formaldehyde and 1.25% glutaraldehyde in a 0.1 phosphate buffer. The inner ear of barn owls includes the vestibular organ, cochlea, and auditory nerve. As owls depend on their ability to track prey using their super sense of hearing in order to survive, it is important to understand the structures of the ear of barn owls that work to transmit these sounds. The sound waves travel through the owl’s ear canal until they reach the eardrum, through the ossicles, and into the inner ear so that the owl is able to perceive exactly where their prey is located. The feathers on the edge of barn owl’s face creates a disc that works to trap and focus sound, similar to the outer ears of humans. During flight, the left ear receives sounds from below them and the right ear receives sounds from above them. The left ear opening is typically positioned a bit higher than the right ear opening to aid with sound localization and the detection of prey, even in the dark. In some species, the opening has a valve, called an operculum, covering it. The shape of the ear opening, known as the aperture, depends on the species. Owls tend to have asymmetric ears, with the openings being placed just behind the eyes. They are then able to use interaural time difference (ITD) and interaural level difference (ILD) to pinpoint the location and elevation of their prey. ![]() The tympanic membrane then sends these waves through the ossicles of the middle ear and into the inner ear that includes the vestibular organ, cochlea, and auditory nerve. Sound waves enter the ear via the ear canal and travel until they reach the tympanic membrane. This species has evolved a specialized set of pathways in the brain that allow them to hear a sound and map out the possible location of the object that elicited that sound. The barn owl ( Tyto alba) is the most commonly studied for sound localization because they use similar methods to humans for interpreting interaural time differences in the horizontal plane. These species include barn owls ( Tyto alba), northern saw-whet owls ( Aegolius acadicus), and long-eared owls ( Asio otus). Several owl species have ears that are asymmetrical in size and location, which enhances this ability. Sound localization is an animal’s ability to identify the origin of a sound in distance and direction. Owls lock onto prey by using sound localization. They are able to rotate their head up to 270 degrees, lock onto prey, and launch a silent attack. Owls are very adept nocturnal predators, hunting prey that includes small mammals, reptiles, and insects. For this to work, the owls must be able to accurately localize both the azimuth and the elevation of the sound source. In fact, the sound cues are both necessary and sufficient for localization of mice from a distant location where they are perched. Experiments by Roger Payne have shown that owls are sensitive to the sounds made by their prey, not the heat or the smell. Because they hunt at night, they must rely on non-visual senses. Most owls are nocturnal or crepuscular birds of prey. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |