Subject: How can Sperm whales stand the pressure?

Rui Prieto (rprieto@dop.uac.pt)
Tue, 18 Aug 1998 17:56:48 -0000

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Dear Rick,

That's a deep question!

Indeed the Sperm whales can dive to great depths, but not as deep as 22000
ft (the deepest part of the ocean is the Mariana trench at 11040m=36226 ft).
They can dive at depths greather than 4900 ft and possibly some can reach
more than 9800 ft.

How they can withstand the enormous pressures involved in such dives is one
of the wonders of these animals.

If they were like us, the pressure should crush the rib cage, which protects
the lungs. But that is avoided because unlike in other mammals, the rib
cages of cetaceans are more flexible, having less "true" ribs (ribs joined
directly to the sternum), and more "floating" ribs, which are united only to
the preceding rib by a cartilage. Also, in the sperm whales the costal
cartilages are not ossified, which means that they are flexible. Being
flexible, the rib cage folds under the pressure, instead of breaking.

On the other hand, in humans and other land mammals, when under great
pressures, when the lung squeezes the small veins (capillaries) inside it
suffer ruptures and they start bleeding (called a pulmonary edema).  In the
marine mammals and in the, Sperm whale in particular, because the thoracic
cavity is flexible, the lungs can collapse (be squeezed), without rupture of
the capillaries.

One problem SCUBA divers have to worry about is what they call "the bends".
This is a sickness caused because the pressure makes gases to enter the
blood flow and in other parts (tissues) of the body. When the pressure
falls, small bubbles of gas are formed (like when you open a bottle of 7-Up,
or other sparkling drink).  These bubbles can obstruct the capillaries in
any part of the body (including the brain) which can cause the death of the
diver.
In the Sperm whales, as we have seen, the lung collapses, (or in other words
is totally squeezed) and the air is pushed to the trachea, which is lined
with thick membranes, avoiding the dissolution of the gases in the blood or
other tissues. We believe that there are other complex processes to avoid
the bends in the cetaceans, but this one seems to be rather important.

As you see the Sperm whales, and other cetaceans, are well adapted to the
pressure of the great depths. There are many other adaptations for deep
diving, but I will not put all of them here, because they would fill a book.
Anyway, you can get more information about Sperm whales at these sites:

NOAA Sperm Whale page:
http://kingfish.ssp.nmfs.gov/tmcintyr/cetacean/sperm.html

Univ. Michigan Sperm Whale Info:
http://www.oit.itd.umich.edu/bio/Chordata/Mammalia/Cetacea/Physeteridae.shtm
l

The Sperm Whale Project: http://www.alaska.net/~pratt/

The Sperm Whale: http://library.advanced.org/2605/sperm.htm


Enjoy your research, and come back with other interesting questions like
this one,

Cheers,

Rui  :- +);


-----Original Message-----
From: rick <rick@cosmoaccess.net>
To: rprieto@dop.uac.pt <rprieto@dop.uac.pt>; pita@whale.wheelock.edu
<pita@whale.wheelock.edu>; kburnett@whale.wheelock.edu
<kburnett@whale.wheelock.edu>
Cc: freddythebird@hotmail.com <freddythebird@hotmail.com>
Date: Domingo, 16 de Agosto de 1998 22:46
Subject: sperm whale


>i know that sperm whales dive almost 22,ooo feet to eat there
>prey(squid).i wass wondering how do they withstand the pressure?
>

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