Subject: [Tweeters] White meat versus dark question
Date: Dec 10 05:49:22 2010
From: JChristian Kessler - 1northraven at gmail.com


hopefully building on this thread, what I was told or what I read -- and I
am not, like many of you, a scientist -- is that the dark meat is muscles
adapted to long duration power, like duck flying muscles or tuna (or some
other deep sea fish), while white meat is for sudden explosive power
movements that are of such short duration that they involve no oxygen
replacement, like Turkey or Grouse escape flights, or Large-mouth (or
Small-mouth) Bass prey capture strikes. But this only addresses how it is
adaptive, not how it works. And it raises the question of whether it is the
same or similar mechanisms in two different Orders.

Chris Kessler
Seattle

On Fri, Dec 10, 2010 at 12:55 AM, Will Markey <yekramw at gmail.com> wrote:

> I have been waiting for Dr. Paulson to enter into the fray because it has
> been so long since I had any biology courses. However, I will attempt to
> recall what I learned in Zoology so many (40???) years ago, from him and
> severaql other professors. Please remember it has been 40 years, so exact
> spelling or terms may be a little off - and I am far from an expert on the
> Order of Aves.
>
> If I remember correctly, there is a different hemoglobin, called
> met-hemoglobin, in the dark meat of birds. It has a higher oxygen carrying
> capacity than normal hemoglobin. The birds that fly long distances, ducks,
> etc. have this type of hemoglobin in their flight muscles. The ground
> dwelling birds that tend to run more (turkey, chickens, etc) have the
> met-hemoglobin in thigh and leg muscles.
>
> This is the black and white of the issue.
>
> Of course, there is always a gray area. Biology would not be fun if
> everything was black and white. Where would be be if gulls did not cross
> bread or if they started out white in their first year?? Identification of
> them would be so boring!
>
> Perhaps the birds that are, for example, ground dwellers but do not have
> dark meat for their "running muscles" have "recently" become ground dwelling
> birds. Maybe they lack the gene/s for met-hemoglobin? Maybe convergent
> evolution will occur in the next million years and they will develop
> met-hemoglobin in their running muscles. Maybe all birds have the genes for
> met-hemoglobin but it takes a slight mutation to turn them on. - - - Maybe
> it will only be 10,000 years!
>
> Questions that have occurred to me from these e-mails -
>
> Does any Zoologist know if small ground-dwelling birds (Dippers, Towhees,
> etc.) have met-hemoglobin in their leg muscles? Is it all or nothing for
> met-hemoglobin? Is there a mix or ratio of hemoglobin to met-hemoglobin in
> bird muscle tissue? If so, this would answer the above question about all
> birds having the gene/s for met-hemoglobin. Does a quail or chucker have
> some met-hemoglobin? Does a gull have met-hemoglobin in its flight
> muscles? What about all the birds that are not "game birds? has anyone
> looked at them?
>
> Is there a doctoral thesis here??
>
> What ever the answers are, it sure makes birds interesting to study and
> think about!!
>
> Will Markey
> East of Auburn on Soos Creek
>
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