Rotifers (Rotifera) are animals which occur in every type of aquatic environment, both marine and freshwater; they dwell also in moist soil. They owe their wide distribution to rapid reproduction. Due to their high abundances, they play an important role in freshwater ecosystems. The world's fauna includes about 2000 rotifer species, 1350 of them being reported from Europe (Bērziņš 1978). So far, about 480 species belonging to the Monogononta have been recorded in Poland, a further 156 of them being supposed to occur in the country (Bielańska- Grajner and Radwan 1997, Ejsmont-Karabin et al. 2004). As evidenced by the research reported hitherto, the order Bdelloidea is represented by 117 species (Bielańska-Grajner et al. 2013).

This publication is a tribute to the eminent Polish researchers of rotifers who have contributed considerably to the knowledge of rotifer taxonomy, biology, and ecology.While paying homage to those scientists, particularly to Antoni Wierzejski, Antoni Jakubski, Jerzy Wiszniewski, and Leszek K. Pawłowski, we wish to emphasise that the book draws substantially upon their work and, at the same time, provides an overview of 100 years of Polish studies on rotifers.

Aparticularly important place in the history of Polish rotifer research belongs to Jerzy Wiszniewski who discovered and described the rich and extremely interesting world of psammic rotifers which inhabit interstitial spaces of lacustrine beach sands. His last work, entitled “Fauna wrotków Polski i rejonów przyległych” [“The Rotifer Fauna of Poland and Adjacent Regions”], published posthumously in 1953, contains his message, his last will, addressed to subsequent generations of Polish researchers. The message focuses on the importance of comprehensive research on the biology and ecology of rotifers inhabiting diverse and specific ecosystems and habitats. He wrote: “The future studies should aim, on the one hand, at obtaining a more detailed knowledge of the faunas of habitats that show a considerable potential (small water bodies, subterranean waters, acid and brackish waters, muds, mosses, moist leaves and forest litter, and periphyton as well as putative hosts of various parasitic and commensal rotifers, etc.); on the other hand, the research should address relationships between the rotifer fauna and ecological characteristics of its habitats, intensification of rotifer research being an overall goal” [translation: Teresa Radziejewska]. It is the hope of the present authors that this publication will make it easier for future generations of Polish researchers to live up to what Jerzy Wiszniewski expected of them.