Anatomical differences between herbivores and omnivores?

Question

What are differences of herbivores vs omnivores? I do not mean dietary differences (obviously), but physical ones. E.g., afaik herbivores have a much longer digestive tract than carnivores; then there is the difference in teeth, possession of carnivorous instincts or lack thereof, etc. But where is the distinction between herbivores and omnivores? Is there a clear distinction at all, or is the border between the two groups somewhat fuzzy? Or are omnivores merely herbivores who are less picky? ### EDIT ### As pointed out in the comments, the last sentence seems to ask for dietary differences. It is not meant to; the only difference I am aware of is dietary, so it asks whether there are any anatomical distinctions, or the dietary is the only one. I.e. are they anatomically similar, and not distinguishable in the same way herbivores and carnivores are; hence are they herbivores that simply do not mind eating non-plant based food in a while? I hope this serves to clarify. ### EDIT 2 ### I realize that this question is quite broad, so while I am trying to get a good view of the bigger picture, partial answers will be more than welcome!

Answer 1

Herbivores tend to have a cecum, which allows them to digest cellulose, ligand, and other complex plant materials. Herbivores also tend to have "dull" teeth, like cows, to help grind down the plants as they are eating.

Carnivores do not have cecums, and generally have a smaller stomach and digestive tract; which, allows them to reduce time that food spends in their body so they can hunt more efficiently. Also, carnivores are often known for their "pointy" teeth and sharp claws that allow them to grip prey.

Regarding instincts, carnivores tend to have that stalking instinct in which they hunch down, stalk, and pounce on their prey (ex: large cats). Carnivores often evolve a great sense of smell or eyesight to hunt their prey (hawks- eyesight; snake- "smell"/ heat detection). Herbivores, on the other hand, have evolved a high "flight" response and are often found in large groups for herd protection.

Within omnivores, there is often cecum remnant. For example, humans have an appendix which is often thought to be a remnant of a cecum that digested plant matter. Additionally, omnivore teeth do not have strict "dullness" or strict "pointyness". Use the example of cow (herbivore) versus human (omnivore) versus feline (carnivore).

Let me know if you have any other questions!