Cold-blooded animals include reptiles, insects and amphibians such as frogs, lizards, snakes, toads, turtles, salamanders, fish, dragonflies and bees. Cold-blooded animals do not keep a stable body temperature and their bodies change to mimic the temperature in their environment.
A cold-blooded animal who is in a hot environment will have a high body temperature, while a cold-blooded animal who is in a cold environment will have a low body temperature. To warm themselves up, many cold-blooded animals will lay out in the sun and elevate their body temperature.
Cold-blooded animals also vary their activity depending on the environment that they are in. When they are in cold environments, they become lethargic and move slowly; when they are in warmer environments, they are quite fast and active. Some species of fish have protein running in their blood that works as a kind of "anti-freeze" to keep the fish from dying in extremely cold temperatures.
The advantage to being cold-blooded rather than warm-blooded is that cold-blooded animals do not need as much energy as warm-blooded animals do in order to survive. They also do not need as much food and will survive even if they are unable to get food for long periods of time. Cold-blooded animals also have stronger immune systems.