Whale Blood vs Human Blood

From: Kim Marshall-Tilas (kimm@oceanalliance.org)
Date: Sun Dec 17 2000 - 10:48:52 EST


>Questions and Answers:
>Hi Hoe and Joey,

Please refer to WhaleNet pages for additional information on whale
anatomy, try the
http://whale.wheelock.edu/howtofind.html page and do a search.

>My son is doing a project on whales. One of the things we want to do is
>show some of the adaptations that whales have for diving. I understand that
>whale blood has more oxygen carring capacity than human blood. We want to
>make some fake whale blood to point this out. It will be water with red
>sponges. We need some more information so we can make our
>demonstration accurate:
>- How much bigger are whale red blood cells than humans, or how else do they
>carry more oxygen?

>Is has been found that the oxygen carrying capacity of red blood
>cells in whales is not signifcantly different than that of land
>mammals but whales do have a higher volume of blood than humans and
>the red blood cell surface is about 1.5 times larger. This permits
>fast absorption and emiision of oxygen needed for diving and rapid
>surface breathing.

>- How much more red blood cells do whales have than humans on a volume
basis? (that is x% vs. y%)

If we refer to blood volume, (information referenced from E
Slijper's book 'Whales' 1979, Cornell University Press.) He states
that the heart of a whale is almost 6 feet wide. He doesn't specify
which whale he's talking about though! The ratio of blood to body
weight is similar to other mammals. In blue whales it is about 6.5
%, while in belugas it is 5.5 %. Example: If humpback whales have an
average of 6% of blood relative to body weight, and the average body
weight of a humpback is between 30 and 34 tonnes then I guess this
would mean between 400 and 450 gallons of blood.

Relative Information:
Marine mammals can dive deep without getting the bends because they
have a greater ability to transport oxygen across lung membranes,
have a higher percentage of oxygen in their blood, and a high
carbon-dioxide tolerance. During deep dives these animals reduce
their heart rate (bradycardia) and peripheral blood flow and
circulation to all areas except the heart and brain. Cetaceans can
exhale as much as 88% of its lung air with a single breathe (humans
approx. 12%). They also collapse their lungs at about 100m which
prevents the absorption of nitrogen into the blood, thereby
preventing the bends. Oxygen use is reduced and heat loss inhibited.
They regain the ability to dive by maximizing cardiovascular and
respiratory activity at the surface by varying breathing techniques.

These adaptations to the respiratory system have allowed deep diving
in mammals. They do not suffer apnea or asphyxia, and they avoid
decompression sickness despite the retention of air within the
respiratory system.

References:
1. Harrison, R.J., Functional Anatomy of Marine Mammals, Academic
Press: New York, 1974
2. Leatherwood, S., Reeves, R., Whales and Dolphins (The Sierra Club
Handbook), 1983

-- 
Kim Marshall-Tilas
Senior Director
Ocean Alliance/Whale Conservation Institute
191 Weston Road, Lincoln, MA  01773
781.259.0423 or fax 259.0288
www.oceanalliance.org



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