Hippity and Hop, the frogs shown in the photo, are ectothermic organisms. This means that their body temperature comes from the environment around them rather than from their metabolism, as what happens in endotherms. This means that if they are too cold, they need to sit out in the sun for a while to warm up and, if they are too cold, they need to rest in the shade to cool down. Most amphibians, lizards, snakes, turtles, many fishes, and most invertebrates are considered to be ectothermic. An advantage ectotherms have over endotherms is that they require a smaller food source in comparison to endotherms in equal size. This is because endotherms depend on their metabolism to help maintain their body temperature while ectotherms depend on their environment. Another advantage ectotherms have is that they are usually more tolerant of large fluctuations in internal temperature and regulate their internal temperature by behavioral means (such as laying the a sunny area or in a shady area).