Putting some clothes on might be a good start...

cantankerii said:
Putting some clothes on might be a good start...

It doesn't work if you can't generate heat yourself. ;)

dogwalker said:
It doesn't work if you can't generate heat yourself. ;)

Everything living generates heat. Reptiles generate just as much heat for the same level of activity as mammals. The difference is that they don't thermoregulate; they don't shiver or sweat. They just let their body temperature match the environment.

degenstoic said:
Everything living generates heat. Reptiles generate just as much heat for the same level of activity as mammals. The difference is that they don't thermoregulate; they don't shiver or sweat. They just let their body temperature match the environment.

Reptiles are poikilotherms so no they don't produce body heat.

nashizal said:
Reptiles are poikilotherms so no they don't produce body heat.

"poikilotherm - an organism that cannot regulate its body temperature except by behavioral means such as basking or burrowing."

That's what I said.

It's not "an organism that doesn't produce heat" because that's thermodynamically impossible. Nothing is 100% efficient. For work to be done, there must be a potential energy gradient, and heat must be produced as a byproduct.

80% of the chemical energy in food is converted to waste heat, and 20% is converted to motion.

degenstoic said:
Everything living generates heat. Reptiles generate just as much heat for the same level of activity as mammals. The difference is that they don't thermoregulate; they don't shiver or sweat. They just let their body temperature match the environment.

Uhhh... no.
The metabolism of Mammals, or avians, is made to generate heat even standing still. Shiver is not really required (but, since reptiles can't shiver, that's a further limitation to their ability to generate heat by themself), and few mammals sweat for thermoregulation, because sweating when you are covered in fur is not really that useful.
That's why a sled dog can sleep in the open in arctic winter, and that's why fur, feathers, or a sweater, can help them to stay warm.
Reptiles produce heat while moving, but, since their metabolism is not made to produce heat, a cold temperature hamper their ability to move as well. You can't say a lizard that's hibernating "run a little to stay warm". She can't run, if it's cold, because her muscles are not warm enough to do so. The heart pumping generates heat but, for the same effect, a cold temperature will slow down her heart rate as well.
That's why reptiles don't have fur or feathers. Putting a sweater on a lizard is as useful as putting a sweater on a stool, and expecting it to warm up.