A parasite is an organism that steals resources from another organism in order to survive. Our planet is home to all kinds of parasites and organisms that host them.
While some parasites live off plants, other parasites need animals. Lisa Shipley, a WSU professor who works with animals in the deer family, said some reindeers are host to a parasite that is so small we’d need a microscope to see it. It’s a kind of nematode more commonly called a brain worm.