Describe how being ectothermic influences a reptiles lifestyle?

Reptiles must depend on outside sources for heat. Sunshine ,primarily , or sun-warmed rocks. At night they go to their dens where the temperature is not as cold as outside, and out of cooling winds. They will seek out any heat source, so you hear those stories about snakes in sleeping bags, garages, coiled up on top of car engines, under houses etc. All true, but they are just trying to stay warm .