What defines an obligate parasite?

An obligate parasite is defined by its dependence on a host organism for its survival and reproduction. This means that it can only complete its life cycle within a specific host or hosts. The relationship is so interdependent that the parasite cannot live freely in the environment without the host. This characteristic is distinct from organisms that are free-living or can survive independently of any host. Understanding this concept highlights the specialized nature of obligate parasites in the ecosystem, where their life strategies often evolve to exploit host resources effectively.