page_title: Theodoxus fluviatilis
section_title: Parasites and predators
hierarchical_section_title: Theodoxus fluviatilis / Ecology / Parasites and predators
caption_attribution_description: English: Common roach on exhibition Subaqueous Vltava, Prague 2011, Czech Republic Čeština: Plotice obecná, (Rutilus rutilus) na výstavě Pod hladinou Vltavy, Palác Kinských, Staroměstské náměstí, Praha 2011
context_page_description: Theodoxus fluviatilis, common name the river nerite, is a species of small freshwater and brackish water snail with a gill and an operculum, an aquatic gastropod mollusk in the family Neritidae, the nerites.
  This widely distributed neritid snail species occurs from Europe to Central Asia. It has a thick shell with a calcified operculum. The coloration pattern on the shell is very variable. Theodoxus fluviatilis lives in freshwater and in brackish water, in rivers and lakes on stones. It feeds mainly by grazing on biofilms and diatoms.
  Some of the populations of this species are spreading, and these can reach densities up to thousands of snails per square meter. Females lay egg capsules, each of which contains a large number of eggs, but only one snail hatches from the capsule. The snails reach sexual maturity in a year, and the total lifespan is 2 or 3 years.
context_section_description: Parasites of Theodoxus fluviatilis include several species of trematodes. The snail serves as first intermediate host to Plagioporus skrjabini and as second intermediate host to Cotylurus cornutus. Asymphylodora demeli is also found in this small snail, as is Notocotylus zduni. This small snail is also parasitized by several species of ciliates. It is the main host for the ciliate Trichodina baltica; the snails are usually 100% infected in the mantle cavity Another ciliate found in the mantle cavity is a species of Scyphidia. Two other parasitic ciliate species found in this snail are Protospira mazurica, and Hypocomella quatuor. Predators of Theodoxus fluviatilis include the common roach (a freshwater fish), Rutilus rutilus. Theodoxus fluviatilis is also the prey of some birds.
caption: One of the known predators of Theodoxus fluviatilis is the common roach, Rutilus rutilus
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