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Re: FEATHERS DO NOT=ENDOTHERMY



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
mammals. 

[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 ]