Re: Hot-blooded marine reptiles

[GSP1954@aol.com]

Endothermy merely means that the majority of body heat is generated 
internally and does not necessarily imply a high metabolic rate is an animal 
can 
use size and insulation to retain heat despite a reptilian resting metabolism, 
or is exercising hard and long enough (such as larger sustained flight 
insects).  Endothermy achieved via a normally elevated resting MR is 
tachymetabolism. Some tuna do have elevated resting metabolisms like birds and 
mammals. 

GSPaul

> Who needs endothermy when you've got your own built-in central
> heating?
> 
> Endothermy IS your own built-in central heating.

Endothermy is more like setting fire to you wallpaper to keep warm than a 
'central heating 
system'. The system in tunas and sharks is elegant and reuses what would 
otherwise be wasted 
heat. Our outrageously leaky cells are more of a sledgehammer approach to 
homeothermy<</HTML>