Is a parasite a vertebrate or invertebrate?

Answer 1

It is not necessarily either nor is it necessarily an animal. A parasite is any organism that benefits from a symbiotic relationship that harms its host. We commonly think of parasites as invertebrate animals such as worms or insects which feed on the blood or nutrients of their host. However, any infectious agent such as harmful bacteria, are considered parasites. Non-animal organisms cannot be classified as vertebrate or invertebrate. Even some plants, such as mistletoe, are parasites to other plants. Some species of lamprey, which are vertebrates, are parasites that suck the blood of other fish. Some birds are brood parasites, laying their eggs in the nests of other birds, often killing their host's true offspring.