Fossilized Inner Ear Bone of Whale
The whale ear has specific adaptations to the marine environment. In humans, the middle ear works as an impedance matcher between the outside air's low impedance and the cochlear fluid's high impedance. However, in aquatic mammals, such as whales, there is no great difference between the outer and inner environments. Instead of sound passing through the outer ear to the middle ear, whales receive sound through the throat, from which it passes through a low-impedance fat-filled cavity to the inner ear. The whale ear is acoustically isolated from the skull by air-filled sinus pockets, which allow for greater directional hearing underwater. This example is from a Blue whale are rorquals (family Balaenopteridae), a family that includes the humpback whale, the fin whale, Bryde's whale, the sei whale, and the minke whale. The family Balaenopteridae is believed to have diverged from the other families of the suborder Mysticeti as long ago as the middle Oligocene. It is not known when the members of those families diverged from each other. Size: 2 ½ inches long by 1 ½ inches wide by 1 ½ inches thick. Age: 5 million to 25 million years old. Location: found at Mosquito Island, Lancaster County, Virginia in the lower Rappahannock River. A great "show and tell" piece.