Re: What is an "active ectotherm"?

["Jonathan R. Wagner" <znc14@ttacs1.ttu.edu>]

At 04:03 PM 10/10/96 -0500, Mickey wrote:

>Sorry for the pun, Jonathan, but you're out of your element.  Others

        Deserved it.  Let's call a moratorium on the things, ok people?
        :)

>Jonathan wrote above would sound perfectly reasonable.  However, if
>you subsequently took a course in heat transfer you'd see where he's
>erred.

        Touche'.

>Think of an animal as a little furnace which burns sugars, fats and
>sometimes proteins.  The temperature of the animal is going to depend
>on the rate at which heat is produced by the burning and the rate at
>which heat is being lost to the environment.  The animal's temperature
>is stable when these two rates are equal.

        So, like us, fish are fighting an uphill battle all the time as
well.  Don't some of them have special low-temperature enzymes as well?  Or
was that some insects.  Sounds to me like they're running an entirely
different metabolic show than terrestrial vertebrates!

>the rate of heat transfer is also proportional to how well the
>surroundings can take the heat away.  We stay warmer in air of a given
>temperature than we would in water because the water takes heat away
>better than air.

        Interesting...  Except I guess the disadvantage for us is that that
air won't be staying at a "given temperature" for too long, even in the tropics.

>That means that a smaller temperature difference is
>required between you and the water in order to get the same heat
>transfer that you would get between you and the air.

        The greater the specific heat, the greater the heat flow?  I am
aware that many fish have insulation, but does their lack of
marine-mammal-like levels of fat mean that, swimming efficency or no, they
generate more than enough heat to keep their little bodies going?  I've
heard salmon have a lot of fat (salmon may taste like pumkin pie, but I
won't eat the filthy... things)...  It really does make me wonder if the
first terrestrial vertebrates were ectothermic heterotherms (bradymetabolic?
Insert your favorite neo-latin compound here?) by  default or by design...

>Ok, I think I've beaten that horse to death.

        Yup.  :)

        Wagner

P.S.  Thanks for the refs, Mickey.
+--------------------------------------------------------------------------+
| Jonathan R. Wagner                    "You can clade if you want to,     |
| Department of Geosciences              You can leave your friends behind |
| Texas Tech University                  Because your friends don't clade  |
| Lubbock, TX 79409                               and if they don't clade, |
|       *** wagner@ttu.edu ***           Then they're no friends of mine." |
|           Web Page:  http://faraday.clas.virginia.edu/~jrw6f             |
+--------------------------------------------------------------------------+