'upthrust,' beaching

From: Pieter Arend Folkens (animalbytes@earthlink.net)
Date: Mon Nov 25 2002 - 00:42:34 EST

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    >what do whales have to do with upthrust?
    >-why is a whalein serious troble when beached?

    Dear Farah:

    I would guess that you are in Sri Lanka and are in the 6th grade/ Am
    I correct? I got a very similar question from two students in Sri
    Lanka. Here is how we exchanged information on the subject:

    Rahul found this definition of upthrust in an encyclopedia:

    I found the answer to the first one in my mum's encyclopaedia, the
    upthrust is what keeps the whale from sinking in the depths

    I elaborated further saying:

    'Upthrust' is essentially 'buoyancy' or 'flotation.' Gravity would
    cause something to sink, but buoyancy is: The upward force that a
    fluid exerts on an object less dense than itself.

    As for the second question, whales are designed to float in water.
    They are also relatively big and heavy. (Fat floats.) When on a beach
    their weight puts pressure on their internal organs. Imagine yourself
    being squeezed by your parents -- it can be hard to breathe. They are
    also designed to be thermal neutral in water. On land and in the sun
    they will become much too warm and go into heat stroke. It's the
    opposite of you being stranded in the water -- after a time you'd
    become hypothermic (loose too much body heat) because you are not
    adapted for life in the cool ocean water. Another way to think about
    it is for you to put on many layers of heavy coats on a hot day. You
    would become very hot indeed.


    Pieter Folkens
    Alaska Whale Foundation


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