parasitizes

Parasitizes is the third-person singular present tense of the verb parasitize, meaning to utilize another organism, the host, as a source of resources and living space while typically harming the host. In ecology and biology, parasitism is a type of symbiotic relationship in which one partner benefits at the expense of the other.

Parasites are diverse and can be classified by location and lifestyle. Endoparasites inhabit the interior of the host, such as tapeworms, flukes, and many protozoans, while ectoparasites live on the exterior, such as ticks, fleas, and lice. They can be obligatory, requiring a host to complete their life cycle, or facultative, able to exploit a host but also capable of free living. Some organisms are parasitoids, whose development inside or on a host ultimately kills the host.

Life cycles range from direct to indirect. Direct cycles involve a single host species, whereas indirect cycles include one or more intermediate hosts or vectors, such as mosquitoes in the transmission of malaria by Plasmodium. Host specificity varies, with parasites ranging from specialists that infect specific hosts to generalists capable of infecting multiple species.

The effects on hosts can be substantial, including nutritional drain, tissue damage, disease, and reduced survival or fertility. These effects can influence population dynamics, community structure, and ecosystem processes. Hosts may respond with immune defenses or behavioral changes, while parasites adapt with strategies to evade defenses, reproduce, and optimize transmission.

Parasitism is widespread across biology, from microbes to vertebrates, and has shaped the evolution of both parasites and hosts. The term parasitizes is commonly used to describe the action of a parasite exploiting a host in this way.