RÉSUMÉ

Issues of terminology concerning the photomovement of freely motile microorganisms and preliminary results of studying photomovement of cells in hyperhalobic species of Dunaliella Teod. (Dunaliellales, Chlorophyceae, Viridiplantae) in comparison with photomovement peculiarities of other flagellate algae, representatives of other taxa (genera, orders, classes, kingdoms of the organic world) are discussed. It is shown that with an increase in phylogenetic distance between taxa the distinctions in their photobehavior, structure, and mechanisms of functioning in photoreception systems become deeper, during the process of sensory transformation of a light signal to motile reactions of different types, in the activity of the flagellar apparatus. Therefore, data on features of photomovement of algae are of interest as additional differential criteria are described in evolutionary biology, phylogenetics, systematics, and taxonomy of algae. Along with distinctions, we also noted some common fundamental features in photomovement processes and their photoregulation in flagellates; these features do not depend on taxonomic positions of the studied organisms. The importance of photobiological researches of photomovement of algae in adjacent fields of science is discussed: ecology (including autecology), geography of algae, applied phycology, in particular, biotechnology, and environmental biomonitoring.