[ConfusedHermit (OP)]

What animal has the most efficient kind of thermoregulation (or what would better than sweating, like we do)?

[Don_1]

It rather depends on your point of view.

Sweating may be a good way to loose heat, but it is not efficient.

Having your own central heating system is all very well, particularly if you live in the polar or temperate regions, but again, it is not efficient.

For efficiency you need to look to the ectotherms; insects, reptiles etc. These animals do not need to consume vast quantities of food, as we do, of which much is to power our heating system. Heat from the sun is free and allows the animal to consume only that which it requires for growth, perambulation, mating etc. Cooling requires only shade.

[ConfusedHermit (OP)]

Ectotherm. I'm learning new words very quickly here :{D~

So basically there isn't a system as convenient as 'I'm hot, I'm going to turn on my internal cooler and be back to normal' and vice versa in the same organism? Fair enough.

Thank you!