Most animals eat the organs since they have the right amount of vitamins and minerals that are needed for the health of the animal, the bones provide minerals and a way to clean teeth.
Most animals do not eat every single part of the dead animal body. They tend to eat the meat and some of the organs. The tail doesn't really provide much nourishment. The head doesn't provide much at all either.
Yes, there are some animals that are considered vegetarians because the do not eat any meat at all, including heads,organs, and tails. They are also animals that eat their own tails but not other animals tails.
