low water levels up to a certain extent by forming a protective layer on the underside of the shell. In Central European forms, this is possible only to a limited extent, but they may survive low water levels by adhering firmly on the stone surface. References Further reading Streit B. (1981). "Food searching and exploitation by a primary consumer (Ancylus fluviatilis) in a stochastic environment: Nonrandom movement pattern". Revue Suisse Zoologie 88: 887-895. External links Ancylus fluviatilis at Animalbase taxonomy, short description, distribution, biology, status (threats), images Ancylus fluviatilis images at Consortium for the Barcode of Life photo 1 photo 2 Planorbidae Gastropods of Asia Gastropods of Europe Freshwater snails of Africa Freshwater animals of Asia Freshwater animals of Europe Gastropods described in 1774 Taxa named by Otto Friedrich Müller