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On Thu, 24 Oct 1996, guy leahy wrote:

>         Personally, I suspect that external insulation, in the form of
> fur or feathers, is far more diagnostic of high resting metabolic rates,
> since it is (a) absent from all living ectotherms, and (b) is functionally
> linked to tachymetabolic endothermy.  Insulation reduces the rate of heat
> transfer between an animal and its environment, thus allowing species with
> high rates of endogenous heat production to maintain high stable body
> temperatures, even in cold climates.  Insulation also functions to
> reduce solar heat loads, thus reducing heat stress.

        I was blindly guessing along these lines, but there are a few
creatures I can't quite figure out- velvet wasps and tarantulas, mainly.
Are they just using their hairs as solar reflectors? I'm not sure how
legitimate the comparison is with the full insulatory coats of birds and

[I'm not sure about velvet wasps, but irrespective of other uses for
 their hairs, tarantulas use them as a defense mechanism.  They shoot
 them at potential predators.  Some captive tarantulas have bald
 abdomens because they get stressed by handling. -- MR ]