Why are animals classified as either carnivore, omnivore or herbivory when no animal eats 100% plant or flesh?

Question

Why do we use these terms when its not 100% true, you have carnivores that may once in a blue moon eat grass or someother plant or a herbivore that eats flesh once in a while by there desire or by mistake.

The defintions say that so and so either eats flesh or plants it doesnt say they eat whatever most of the time but will once in a while eat this or that

Answer 1

we never feed our cattle anything we have not grown, cattle are not adept at eating any flesh, they are designed to be grazers. farmers who feed pellets to their herd do so from recognised suppliers as it has been noted that ground animal parts were being used, so it was down to ignorance of the owners.

carnivores eat grass like we take a medicine, its not food but a means to be sick & clear the stomach or to poo & clear the intestines

Answer 2

I think the issue is what food source sustains their body systems, and their body systems are adapted to it- eg a cow might by accident chew a grasshopper, but thats not why it needs 4 stomachs, and the processing of meat through a ruminant animal would not be efficient

tags are useful but they are never as black and white as you might think- still if i was to say lions are herbivores when they may simply digest plant material as a fibre source not an energy source -then that would be misleading, and not really tell me much about their environment or their particular adaptations to it eg claws, incisors etc

Answer 3

The idea is to try to generally group animals together. Despite the fact that a wolf tends to do more grazing on non-meat materials than cats, they still are very similar in their dentition and gastro-intestinal system and neither has the appropriate dentition or gastro intestinal system to properly digest most plant material (regardless of whether they ingest it or not).  

It would make sense to lump them in a category that makes them closer to cats than say, reindeer.  

You then further subdivide groups based on finer information so that while cats, bears and wolves are all carnivores (in the order Carnivora), they're divided on a number of other issues, including the fact that bears tend to be omnivorous (and therefore have the dentition to utilize the plants).

If a carnivore had nothing around but plant material, it would soon be deficient in a number of areas which would lead to poor health, and possibly death. If an herbivore began eating only meat on a regular basis, it would also get sick and probably die (their intestinal system is not designed for eating raw meat and handling large loads of bacteria for this - they would be more succeptible to spoiled meat than we are).

The fact is that for most of these animals, the vast majority of the nutrients they get are from the food they are designated as eating (meat for carnivores, plant materials for herbivores).  

So i wonder what your idea is. If you refuse to separate them into groups because a particular group might not be 100% carnivorous, then your answer is to lump it with everything else? We should lump Gnus with Lions? Or is your idea to have a sliding scale and suggest that animals be placed into it if they're say, 90% carnivorous as opposed to 99% carnivorous?

Answer 4

Because their organisms are built to eat either grass, meat or anything. If you eat only grass you die because you need the stuff from the meat. The same is with a cow, if it eats meat will die because the stomach can't use it.

Answer 5

Animals are classified by diet according to what they eat primarily.

Answer 6

The classification is based more on physiology than behaviour. Herbivores have teeth adapted to a mainly vegetarian diet and carnivores have teeth adapted for siezing and killing prey animals. Omnivores have both kinds of teeth. There are also differences in the alimentary tract. Herbivores have more massive guts designed to process foods high in fiber.

Dinosaurs are very good examples of animals whose dietary classification is based entirely on physiology. Theropods like T. rex and Allosaurus had long, fang shaped teeth and sharp claws. They are classified as carnivores. Therasinosaurus had arms which ended in long claws over a meter long. It was a theropod, and the claws suggested it was a preditor, but the teeth were flat and spoon shaped, set in a small head on a long neck. Because of its teeth, Therasinosaurus is now thought to be a herbivorous therapod dinosaur which used its enormous claws for feeding and defense.

Answer 7

In a more general sense, animals are loosely considered carnivores if their feeding behavior consists of preying on other animals rather than grazing on plants (wikipedia)

the classification of animals helps to make the research easier