XKCD - Expanded Hertzprung-Russell Diagram

Reminds me of the interesting factoid: on a power-per-mass basis, our sun produces less Wattage than reptile metabolism. (Reptiles! Doesn't even approach mammals, an order of magnitude greater!) But that surface area-to-volume ratio is important, and as the XKCD author pointed out previously, if you had a whole planet made of mammals, it would put out a fair amount of energy in an unexpected scale-dependent phenomenon, although metabolism would not continue - turns out where powering stars is concerned, fusion beats glycolysis or respiration.