Fish, amphibians, reptiles, birds, and mammals are all included in the diets of the many carnivorous and omnivorous reptilian species. Some are generalists, feeding on many different types of prey, while others are specialists, feeding on a limited number of species of prey. Most extant reptiles are carnivores with a sit-and-wait feeding strategy; whether reptiles are cold blooded due to their ecology is not clear.
Energetic studies on some reptiles have shown active capacities equal to or greater than similar sized warm-blooded animals. Most reptiles are carnivorous, and many primarily eat other reptiles. Diets range from entirely carnivorous to (almost uniquely among reptiles) strictly herbivorous, with the full range of omnivorous stages in-between.