Vocal Cords & Communication

From: Kim Marshall (kimm@oceanalliance.org)
Date: Mon Feb 17 2003 - 10:29:21 EST

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    > i am 12 years old.I have studied whales for 7 years and plan on becoming
    > marine bioaligist but i have noticed i have never seen enything about the
    > difference in whale vocal cords i would like to know because i need to know
    > for a science fair for a totally never used science project
    > Reply: Dear Asia,
    > Whales don't have vocal cords like we do, but they appear to have membranes of
    > similar form which may serve the same purpose as vocal cords. They produce
    > sounds by forcing air from their nasal passages into sacs, without exhaling
    > any air. It is believed the sounds are made in the throat or larynx. After
    > taking a breath of air, they can reuse that air several times to make sound
    > before exhaling it.
    > Whales also use a mechanism called echolocation to 'see' with their ears.
    > They direct a beam of click-like sounds and listen to the echoes that return
    > from objects in the path of the sound. If you direct a flashlight at
    > something in the dark, you illuminate the object with light and you can see
    > it. Whales can 'illuminate' a silent fish with sound in order to 'see' it.
    > From the returning sound, the whale learns the size, shape, speed, and
    > direction of the subject. Dolphins can even beam their sound waves into mud
    > to find hiding fish! (Seawater and flesh have approximately the same density,
    > so the sounds whales emit penetrate the flesh of submerged animals. It has
    > been suggested that whales can actually see the inside of their companions and
    > their prey. The resulting image might look like an ultrasound picture). Fish
    > can't hear the high pitched sounds, so they don't realize they are being
    > looked over. It has been postulated that some cetaceans, such as the sperm
    > whale, may even use strong pulses of sound to stun their prey!
    > Toothed whales generally spend most of their time in shallow, coastal areas
    > and use sharp, high frequency sounds that don't travel very far through the
    > water before being converted into heat. Short, high-pitched, rapid sounds
    > used on objects in close proximity allow whales to hear the finer details.
    > Some types of baleen whales (like blue and fin whales) spend a lot of time in
    > deep, dark waters and use loud low frequency, long-ranging sounds to
    > communicate and navigate the seas. Low frequency sound can travel for long
    > distances, but only gives broader details. The distance traveled depends
    > largely on the depth and temperature of the ocean the sound is sent from
    > (temperature and pressure change the conductive properties of water).
    > Fin and blue whales are examples of loud-voiced whales. They are larger
    > baleen whales that are found in all oceans. While humpback, right, bowhead,
    > and gray whales have specific breeding grounds, so far no one has found a
    > breeding ground for the rorquals other than the humpback. Fin and blue whales
    > may not need a distinct breeding ground. They may just start calling with
    > their loud, low songs to potential mates. These calls can travel for hundreds
    > and even thousands of miles away. It is not out of the question that the
    > calls may also contain information about where food is.
    > Humpback whales make rhythmic, repeated patterns of sounds, or songs. Their
    > songs (sung mostly by males) seem to be related to mating and may function the
    > same way bird calls do; as a challenge by males to other male rivals and as a
    > means of attracting females. Suspended head down in the water, very still,
    > humpbacks can sing for hours. All humpbacks sing the same song on the same
    > breeding ground even if they are very far apart. The lowest sounds in their
    > songs are audible over long distances.
    > Other possible forms of communication that whales employ are breaching,
    > lobtailing, and flipper slapping, which may be ways of sending sounds intended
    > as communication at short range through the water. They could be saying, "I'm
    over here!

    Good luck!

    Kim Marshall
    Executive Director
    Ocean Alliance (Whale Conservation Inst. & the Voyage of the Odyssey)
    191 Weston Road, Lincoln, MA 01773
    781.259.0423 ext. 14 fax 259.0288
    www.oceanalliance.org www.pbs.org/odyssey
    Please support our efforts to conserve whales and their ocean environment
    through research and education :)

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