Pandoravirus sediments. Pandoraviruses, like other marine viruses, prey on plankton, which are organisms that live in the water column and form the basis of the food chain for other marine species. More study and research needs to be done in order to confirm the prevalence of Pandoraviruses in different environments. Currently, not much is known about their role in marine ecosystems. Pandoraviruses do have approximately 93% of their genes that are unidentifiable with any other microbes, suggesting they may belong to an as of yet undescribed "fourth domain" aside from Bacteria, Archaea, and Eukaryotes. Viruses as a whole are not popularly
Freshwater snail of primitive "prosobranch" gilled snails which have a shelly operculum. The Caenogastropoda are a large group of gilled operculate snails, which are largely marine. In freshwater habitats there are ten major families of caenogastropods, as well as several other families of lesser importance: Basommatophorans are pulmonate or air-breathing aquatic snails, characterized by having their eyes located at the base of their tentacles, rather than at the tips, as in the true land snails Stylommatophora. The majority of basommatophorans have shells that are thin, translucent, and relatively colorless, and all five freshwater basommatophoran families lack an operculum. Several different freshwater snail