Subject: eyelids (fwd)

Michael Williamson (pita@whale.simmons.edu)
Thu, 27 Feb 1997 10:02:43 -0500 (EST)

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J. Michael Williamson
   Principal Investigator-WhaleNet <http://whale.wheelock.edu>
   Associate Professor-Science
   Wheelock College, 200 The Riverway, Boston, MA 02215
voice: 617.734.5200, ext. 256
fax:    617.734.8666, or 617.566.7369
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---------- Forwarded message ----------
Date: Wed, 26 Feb 1997 01:02:07 -0700
From: Pieter Folkens <animalbytes@earthlink.net>
To: Carol Hayward <haywarc@meol.mass.edu>
Cc: pita@whale.simmons.edu, ask@whale.simmons.edu
Subject: eyelids

>Miss Sullivan's second grade class is studying whales.  We would
>like to know if whales have eyelids. Also, we would like to know how
>whales sleep. Please E-mail us back.

Hi kids.

Whales are mammals. As such, they share most of the fundamental features
common to all mammals, including eyelids. ** However, their eyelids are
different. As you might guess, a whale's eyelids need to be heavy duty to
protect them in the harsh ocean environment. Whales also have tears which
work all the time. Your tears are like salty water. Whale tears are thick
and gooey. This is so the tear can protect the eye from the cold, corrosive
sea water.

Whales cannot sleep, at least not the way most mammals sleep. Whales are
conscious breathers. This means they must decide when to breathe. If they
fell truly asleep they would forget to breath. When you breathe your body
pretty much forces you to take regular breaths, even while you sleep. We
can control our breathing to some degree, but our body will always kick in
and force us to take a breath.

A whale typically holds its breath for five to ten minutes. Some whales can
hold their breath for over an hour. Try it. See if you can hold your breath
for two and a half minutes (half the time of a typical short whale breath).
What happens?

Now back to sleep. Whales go into a rest mode. Studies with dolphins
suggest they can shut down half the brain at a time, keeping the other half
slightly awake to breathe. After about 15 to 45 minutes the sleeping half
wakes up and the other half goes to sleep for about the same amount of
time.

Have you ever tried to fall asleep standing up? What would happen? To keep
your balance, the muscles of your body must keep working all the time
making subtle adjustments to keep you balanced. This is very tiring for
your body and is one of the reasons why we get tired  and why sleep is so
important. Whales, on the other hand, float. They have no feet and can't
stand and so don't need to keep balance like people do. They also don't
need as much sleep. An hour or so twice a day is probably enough compared
to the 7 to 10 hours needed by humans.

** Project: name as many features as you can which are common to all mammals.

Cheers,

Pieter Folkens

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