A carnivore , meaning "meat eater" (Latin, caro, genitive carnis, meaning "meat" or "flesh" and vorare meaning "to devour"), is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging. Animals that depend solely on animal flesh for their nutrient requirements are called obligate carnivores while those that also consume non-animal food are called facultative carnivores. Omnivores also consume both animal and non-animal food, and, apart from the more general definition, there is no clearly defined ratio of plant to animal material that would distinguish a facultative carnivore from an omnivore. A carnivore that sits at the top of the food chain is termed an apex predator.
The word "carnivore" also may refer to the mammalian order Carnivora, but this is somewhat misleading. While many Carnivora meet the definition of being meat eaters, not all do, and even fewer are true obligate carnivores (see below). For example, most species of bears are actually omnivorous, except for the giant panda, which is almost exclusively herbivorous, and the exclusively meat-eating polar bear, which lives in the Arctic, where few plants grow. In addition, there are plenty of carnivorous species that are not members of Carnivora.
Outside the animal kingdom, there are several genera containing carnivorous plants and several phyla containing carnivorous fungi. The former are predominantly insectivores, while the latter prey mostly on microscopic invertebrates, such as nematodes, amoebae and springtails.
Carnivores are sometimes characterized by the type of prey that they consume. For example, animals that eat insects and similar invertebrates primarily or exclusively are called insectivores, while those that eat fish primarily or exclusively are called piscivores. The first tetrapods, or land-dwelling vertebrates, were piscivorous amphibians known as labyrinthodonts. They gave rise to insectivorous vertebrates and, later, to predators of other tetrapods.Carnivores may alternatively be classified according to the percentage of meat in their diet. The diet of a hypercarnivore consists of more than 70% meat, that of a mesocarnivore 50–70%, and that of a hypocarnivore less than 30%, with the balance consisting of non-animal foods such as fruits, other plant material, or fungi.
An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutrients and energy of the sources absorbed. Often, they have the ability to incorporate food sources such as algae, fungi, and bacteria into their diet.Omnivores come from diverse backgrounds that often independently evolved sophisticated consumption capabilities. For instance, dogs evolved from primarily carnivorous organisms (Carnivora) while pigs evolved from primarily herbivorous organisms (Artiodactyla). Despite this, physical characteristics such as tooth morphology may be reliable indicators of diet in mammals, with such morphological adaptation having been observed in bears.The variety of different animals that are classified as omnivores can be placed into further sub-categories depending on their feeding behaviors. Frugivores include maned wolves and orangutans; insectivores include swallows and pink fairy armadillos; granivores include large ground finches and mice.
All of these animals are omnivores, yet still fall into special niches in terms of feeding behavior and preferred foods. Being omnivores gives these animals more food security in stressful times or makes possible living in less consistent environments.