Well, I went to do some research and I came out with this:
"A carnivore (IPA: /ˈkɑrnɪvɔər/), meaning 'meat eater' (Latin carne meaning 'flesh' and vorare meaning 'to devour'), is an animal with a diet consisting mainly of meat, whether it comes from animals living (predation) or dead (scavenging).
In a more general sense, animals are loosely considered carnivores if their feeding behaviour consists of preying on other animals rather than grazing on plants. There are many predatory invertebrates, for example arthropods such as spiders or mantises and various species of predatory land snails and sea snails.
Animals that must eat meat in order to thrive are referred to as obligate carnivores.
Plants that capture and digest insects are called carnivorous plants. Similarly fungi that capture microscopic animals are often called carnivorous fungi.
The designation "hypercarnivore" is used to describe animals that exclusively feed on animal tissue. Additionally, it is used in paleobiology to describe taxa of animals which have an increased slicing component of their dentition relative to the grinding component."[1]
Well it doesn¥t explain why do carnivores eat meat,but probably what kor said,ill try do some more accurate research