Subject: Blubber? (fwd)

Michael Williamson (pita@whale.simmons.edu)
Tue, 31 Dec 1996 12:04:25 -0500 (EST)

Date: Fri, 20 Dec 1996 11:31:03 -0500 (EST)
From: Robert Kenney <rkenney@gsosun1.gso.uri.edu>
To: Squatter <mb4072@gramercy.ios.com>
Cc: pita@whale.simmons.edu, krill@whale.simmons.edu
Subject: Re: Blubber?


On Wed, 18 Dec 1996, Squatter wrote:

> Dear Dr. Kenney
> 
> May I steal a few moments of your time?  Good, now my question is: WHAT 
> IS THE CHEMICAL STRUCURE OF BLUBBER?  I already know that is a staurated 
> fat so it has no double bonds in the fatty acid, but besides that I'm 
> stumped.  Thank you for your time.
> 
> Matthew "Squatter" Michalovic
> Professional High School Student (P.H.S.S.,  pronounced a "fsss")

Matthew:

There is no real answer to your question concerning the chemical structure
of blubber; it's like asking 'What it the chemical structure of pancreas,
or grass, or hot dogs?" Blubber is not a simple chemical compound; it's a
complex tissue like any other body structure.  Blubber is a layer of fatty
tissue between the skin and the muscle in several types of marine mammals,
including whales and dolphins, seals, and manatees.  The blubber layer of
some whales can be more than two feet thick in places.  

Blubber has at least two functions.  One is insulation.  Fat conducts heat
relatively slowly, so it slows down the loss of heat from a warm body to
the cold ocean.  The other function is energy storage.  It's a place for
an animal to stick any extra food energy it eats over its immediate needs
to store for some future time when there might not be enough to eat.  For
example, we believe that large whales (like blue whales) in the Antarctic
eat for only about four months of the year.  They have to eat enough to
last them through the other eight months when they may not feed at all. 
It would be like you eating nine meals a day (maybe you do - I remember
how I ate when I was a teen-ager) from the first day of school until the
end of Christmas vacation, then nothing until the next September. 

Blubber is composed of connective tissue fibers and fat cells.  The
connective tissue is made of collagen, the same chemical found in human
connective tissue and bone.  The collagen fibers make the blubber layer
stiff and tough, but still flexible.  The layer is not the same everywhere
on the whale's body - some places are really thick and some are relatively
thin.  The blubber is also not the same all the way through, but composed of
different layers with different amounts of collagen and oils.

The fat cells are where lipids (fat molecules of a variety of types) are
stored.  For those species which go through a feed-and-starve cycle, the
thickness of the blubber and the amount of oils contained in a section can
change a lot over a very short time.  One English scientist working with
the whalers in the Antarctic during the 1950's estimated that humpback
whales gained about a ton in weight and about one and a quarter barrels in
oil content each week during the feeding season. 

Finally, the fats themselves are very complex.  (Since whale oil was one
of the most important products of whaling, there was a lot of research
done in the past on its chemical nature, and probably hundreds of
scientific papers published.  But since I'm not very interested in that
topic, I don't have copies of the papers handy to give you the details.)
Each species of marine mammal can have a different mix of lipids in its
blubber fats.  The mixture can be different at different places on the
animal's body, and in the different layers of the blubber.  In one
species, the particular kind of prey eaten can affect the chemical nature
of the blubber fats.  The fatty acids which the whale's system uses to
build its lipids come from the food it eats.  For example, whales from the
Atlantic have fatty acids in their blubber that are more similar to fish
oils than those in the blubber from Antarctic whales, which eat more
krill. 

Given the little bit I know about lipid chemistry, I would guess that many
of the lipids in marine mammal blubber are not completely saturated.  The
more saturated the fatty acids in a lipid are, the higher its melting
point.  Vegetable oil, which is liquid at room temperature, is less
saturated than vegetable shortening (e.g. "Crisco"), which is solid at
room temperature.  Many of the lipids which are found in whale blubber are
more oily - some oil will just ooze out of chunks of blubber with no
cooking necessary - so I'd guess they were not completely saturated. 

Cheers,
Dr. Bob Kenney