Subject: Diving

Lori Mazzuca (lorim@soest.hawaii.edu)
Wed, 14 May 1997 11:42:19 -1000 (HST)

Dear David Paul,
	Thak you for your question:  How is it possible for marine mammals
to endure such a long period between respirations without becoming
profoundly hypoxemic, especially in the large energy requirements
necessary for deep diving?
	You are correct if you assume a human would die if it were do what
these air-breathing cetaceans do daily!  They do not suffer from
compressed air-diseases, such as the "bends," since they do not breathe
compressed air when diving.  Because of this they avoid the problem of
absorbing high amounts of nitrogen which occurs when previously inhaled
compressed air expands at the surface.  When they dive, their lungs are
compressed so that air is forced into the nasal passages, the windpipe,
and air sacs around the lungs, and around the sinuses in the head. This
also prevents the absorption of harmful nitrogen through the lung wall.
Roughly forty percent of the oxygen is stored in the blood which contains
a high amount of oxygen storage particles called hemoglobin. Even if a
marine mammal is stressed after chase, you will see them taking
several breaths in a row, almost as if they were "panting." This
supercharges their bodies again with osygen before diving deeply for a
longer period.
	I hope this helps.  If you are in a bookstore or library, check
out the diving chapters in books about marine mammals.  I have condensed
the information in this message.

Sincerely, 
Lori

On Tue, 13 May 1997 Lzdpaul@aol.com wrote:

> Dear Lori,
> I was wondering__ How is it possible for marine mammals to endure such a long
> period between respirations without becoming profoundly hypoxemic, especially
> in the setting of the large energy requirements necessary for deep diving?
> Hope your research is going well.
> Thanx for your time,
> David Paul
>