The Elephant

Friday 26 August 2011

The Basilar Membrane

Posted by kushanandlyn at 05:19

The Basilar Membrane is a stiff structural element in the inner ear that splits the two liquid filled tubes that run along the coil of the cochlea. It has many important roles to the hearing of mammals.

The basilar membrane is the base for the sensory cells of hearing. The hair cells are arranged in order along the basilar membrane, from high-frequency to low-frequency, This gradient is caused by properties of the basilar membrane.

We can assume that the Elephant, who can hear very low frequencies (infrasound), has a very long basilar membrane with more low-frequency sensing hairs.

Physiological Differences

Posted by kushanandlyn at 03:25

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There are three species of elephants which are generally recognized today: the African bush elephant, the African forest elephant and the Asian elephant (also known as the Indian elephant).

African Bush Elephant

Asian Elephant

African Forest Elephant

To the untrained eye, the physiological differences of the African and the Asian elephants can be indistinguishable. There are some physical features that make the two species relatively easy to tell apart.

African elephants generally have large ears. The have large surface area to help keep African elephants cool in the blazing African sun. The Asian elephants using live in cool jungle areas, hence smaller ears.

Asian and African elephants have very distinct head shapes. African elephants have fuller, more rounded heads, and the top of their head is a single dome. Asian elephants have a twin domed head with an indent in the middle.

In African elephants, generally both sexes have tusks, whereas in Asian elephants, only the male grows tusks. There are also some male Asian elephants that are born tuskless.

Anatomical Structure of the Ears

Posted by kushanandlyn at 02:50

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Ears serve several important functions in the elephant. The functions include: regulating body temperature, to ward off potential threats and of course, hearing.

Due to research, we know that elephants have infrasound hearing capabilities. This means that elephants can hear frequencies lower that 20 Herts. Humans can only hear frequencies above 30 Herts. This infrasound ability can be noticed by sudden reaction of elephants to lift their head from drinking, bathing or eating, and act in a peculiar fashion.

Under normal conditions elephants can hear and respond to each other’s loud calls from distances greater than fifty square kilometers of range.

The elephant has a constant problem for temperature control due to their low surface to volume ratio. The ears help regulate the elephant’s body temperature. With a wide surface area of outer ear tissue, hot blood in the arteries is cooled as it is filtered through the vast network of capillaries and veins. Asian elephants in the north that live in cooler conditions have smaller ears. Not only do the ears perform extraordinary hearing abilities they also help in the animal’s homeostasis.

The ear of an elephant is made up of a cartilaginous sheet to which relatively thin skin is closely attached.

http://www.youtube.com/watch?v=rkHrShQhU70