upthrust, beaching

From: Pieter Arend Folkens (animalbytes@earthlink.net)
Date: Wed Nov 20 2002 - 11:28:48 EST

  • Next message: Pieter Arend Folkens: "killer whales"

    Dear Amani:

    Let me guess, you are in the 6th grade and live in Sri Lanka. Am I correct?

    You asked:

    >Can you plaese give me the answer to Why is upthrust inmportant to whale?

    Apparently your fellow student, Rahul, was given the same question.
    He found the answer to 'upthrust' in an encyclopaedia. Here is what
    he wrote:

    >Khulsum Edirisinghe <khedir@sierra.lk>
    >Subject: Re: upthrust, beaching
    >Thank you for replying so quickly to my question. 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. your answer to my second
    >question is perfect, thanks ever so much! Rahul.

    The exchange between Rahul and me with my answer to his questions
    went like this:

    >I am a student in the 6th Grade in Sri Lanka and I need some
    >information on whales.
    >Could you tell me why upthrust is important to the whale and why the
    >whale gets into serious trouble when it is beached?

    Good to hear from Sri Lanka. I studied whales off northeast Sri Lanka
    in the early 1980s with Steve Leatherwood.

    I need a little more information regarding what you mean by
    'upthrust.' My experience associates that term with geology, which is
    not directly a concern of whales.

    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.


    So, to answer you specifically, '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.


    Pieter Folkens Alaska Whale Foundation


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