Subject: Re: Humpback heart size
Sun, 23 Mar 1997 13:57:41 GMT+1200

I recently was blessed by seeing many humpbacks off Maui.  I asked a
question while on the boat and have since done a bit of research myself.
What is the size of the heart of an adult humpback whale?  I have found
a few references to relative percentage to the animals size and weight,
the general shape; elongated, due to its' placement by the lungs and
thorax.  I have learned of the counter-concurrent circulatory system
which helps minimize heat loss to the colder waters.  All really
fascinating info.  However, is there an approximate measurement of the
size of the heart itself?  Also, what might be the volume of blood in an
adult humpback?

Thanks for looking into this.

Dear Mike,
it sounds like you have been hard at work!  Because weight tells us little about the 
comparative size of the heart, most scientist talk about the weight of the heart as a 
percentage of the total body weight, that's why you are having trouble finding this 

The one bit of information I have is 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 (once again) of blood to body weight is similar 
to other mammals.  I don't have a number for the humpback, but in blue whales it is about 
6.5 %, while in belugas it is 5.5 %.  If humpbacks 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. 

Nathalie Patenaude
Molecular Ecology and Evolution Group
School of Biological Sciences
University of Auckland
Private Bag 92019
Auckland, New Zealand