What reptiles are cold blooded?

Reptiles like high steady body temperatures just as mammals and birds do, however, and this means they have sophisticated ways to manage flows of heat between their bodies and the environment. One common way they do this is to use blood flow within the body to facilitate heat uptake and retard heat loss. A lizard basking in the sun, for example, ramps up its cardiac output. In this way, heat is transferred rapidly from the warm skin, to the body, and the body heats rapidly. Once the lizard has stopped basking, its cardiac output declines, retaining heat within the body so that the body cools slowly. In this way, a lizard can minimize the time it spends soaking up heat, and maximizes the time it can spend doing other essential things, like looking for food and mates or defending territories.