Which type of parasite can survive without a host?

A facultative parasite is defined by its ability to survive and reproduce in a free-living state, without the need for a host organism. This adaptability allows facultative parasites to shift between parasitic and free-living lifestyles, depending on environmental conditions and the availability of hosts. An example of a facultative parasite is certain species of fungi, which can thrive independently in soil or decaying matter when a host is not present.

In contrast, obligate parasites depend entirely on a host to complete their life cycle. They cannot survive long-term outside of a host organism, as they rely on the host's resources for nourishment and reproduction. Endoparasites live inside the host’s body, often in internal organs, which makes their survival solely dependent on the host. Ectoparasites attach to the outside of a host for sustenance, typically feeding on blood or other bodily fluids; similar to endoparasites, they cannot exist long-term without their host.

This distinction illustrates why facultative parasites have a unique survival mechanism compared to obligate, endo-, and ectoparasites.