Virivore (equivalently virovore) comes from the English prefix viro- meaning virus, derived from the Latin word for poison, and the suffix -vore from the Latin word vorare, meaning to eat, or to devour; therefore, a virivore is an organism that consumes viruses. Virivory is a well-described process in which organisms, primarily heterotrophic protists, consume viruses, though some metazoans are known to do so, as well.

Viruses are considered a top predator in marine environments, as they can lyse microbes and release nutrients (i.e. the viral shunt). Viruses also play an important role in the structuring of microbial trophic relationships and regulation of carbon flow.

The first described virovore was a small marine flagellate that was shown to ingest and digest virus particles. Subsequently, numerous studies directly and indirectly demonstrated the consumption of virions. In 2022, DeLong et al. showed that over the course of two days, the ciliates Halteria and Paramecium reduced chlorovirus plaque-forming units by up to two orders of magnitude, supporting the idea that nutrients were transferred from the viruses to consumers.

Furthermore, the Halteria population grew with chlorovirus as the only source of nutrition, and grew minimally in the absence of chlorovirus. The Paramecium population, however, did not differ in growth when fed chloroviruses compared to the control group. Since the Paramecium population size remained constant in the presence of only cholorviruses, this indicated that Paramecium is capable of maintaining its population size, but not growing using chlorovirus as the sole carbon source. These data showed that some grazers can grow on viruses, but it does not apply to all grazers. It was estimated that Halteria consumed between 10,000 and 1 million viruses per day. It's known that small protists, such as Halteria and Paramecium, are consumed by zooplankton, indicating the movement of viral-derived energy and matter up through the aquatic food web. This contradicts the idea that the viral shunt limits the movement of energy up food webs by cutting off the grazer-microbe interaction. The amount of energy and matter passed up would depend on virion size and nutritional content, which would vary depending on the strain.

Viruses are the most abundant biological entities in the world's oceans. The life cycle of a lytic virus is an important process within the worlds oceans for the cycling of dissolved organic matter and particulate organic matter, i.e. the viral shunt. Viral particles themselves also make up a large proportion of the nitrogen and phosphorus rich particles within the dissolved organic matter pool, as they are made up of lipids, amino acids, nucleic acids, and likely carbon incorporated from host cells. It's considered that viruses can complement a grazers diet if ingested, and the microbe is not infected.

General grazing on viruses is widespread throughout the marine environment, with grazing rates as high as 90.3 mL⁻¹ day⁻¹. When both bacteria and viruses are present, viruses can be ingested at rates comparable to bacteria.

Using Oikopleura dioica and Equid alphaherpesvirus 1 (EhV) as a model, scientists estimated the nutritional gain from viruses;

It's suggested that in smaller grazers, viruses could potentially have a more significant impact on host nutrition. For example, in nanoflagellates, the estimated contribution is 9% carbon, 14% nitrogen, and 28% phosphorus.