What characterizes parasites?

Parasites are characterized by their dependence on a host for survival, deriving nourishment at the host's expense. This relationship is essential for the parasite, as it relies on the host’s resources to grow and reproduce. Unlike organisms that live independently and thrive, parasites typically cannot sustain themselves without a host, highlighting the nature of their survival strategy.

The interaction can often lead to various health issues for the host, ranging from mild to severe symptoms, depending on the type of parasite and the extent of the infestation. This relationship is not beneficial to the host, contrasting with beneficial organisms that provide some form of advantage or support to their host. Furthermore, while infestations can sometimes lead to severe complications or death of a host, not all parasites cause immediate death; many allow for prolonged survival of the host, during which the parasite continues to feed. Hence, the correct description of parasites focuses on their dependence and detrimental relationship with their hosts.