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Re: What is an "active ectotherm"?



At 01:11 PM 10/10/96 -0400, Ray McAllister de-lurked and wrote:

>       Some fish (perhaps all that swimion water colder than the freezing
>point of body fluids-circa 28degrees F) have natural antifreeze in the
>body fluids. There have been several papers in the literature in recent
>years, centering of the Antarctoc if I remember correctly.

        Isn't evolution cool (sorry about the pun...)?  What I really want
to know is how they warm themselves up enough to catalyse chemical
reactions.  I mean, the only place heat is going to come from in a fish is
it's own body (and a little from the bodies of its prey).  I suppose that
they are not necessarily homeothermic, as one does not always need many of
those reactions going on all the time, but if they are generating this
internal heat, that makes them endothermic heterotherms.  At least, I think
it does...
        Actually, this came up in a discussion with a geophysics professor.
I hypothesise that, at the time when animals first left the water, they were
presented with a new and fantastic energy source, solar radiation.  Being
rather sluggish in the beginning anyway, I suspect it may have been simpler
to use this new power source rather than develop endothermy, which not have
been too much of a stretch for animals which were used to fighting an
up-hill (up-entropy?) battle against freezing in water (*oversimplification
alert*).  In other words, I am hypothesising that that endothermic
heterothermy in terrestrial vertebrates is an adaptation which was selected
for, and not a default condition of animals waiting around to become spiffy
enough to be warm-blooded, cute, and suck milk (or recite inannities from a
birdcage).
        Perhaps not origional, but worth considering...

>       Keep up the discussion. Someone should summarize the various posts
>for a technical article. 

        Personally, I've been toying with the idea of summarizing at least
my portions of this thread and the BCF debate, so that next time they come
up I can refer people to my webpage rather than clutter people's mailboxes
all over again.  :)

        Wagner
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| Jonathan R. Wagner                    "You can clade if you want to,     |
| Department of Geosciences              You can leave your friends behind |
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