Dep. Invertebrate Zoology, Biology and Soil Faculty, St.-Petersburg University, Universitetskaya nab. 7/9, St.-Petersburg 199034, Russia

Abstract

Individual behaviour of 38 pearlwort species from White See were investigated. Two groups of reactions were described: individual and collective. Behaviour of zooids from different colonies of the same species can be different depending on environment, while the behavioural reactions of colonies of different species are similar. Almost all known main ways of flow formation were revealed for one layer vertical colonies with one and two lines of zooids and for one layer encrusted colonies with one - and many lines of zooid arrangement. It was shown for Shizomovella lineata that the character of channel water transference changes depending on colony age. Many different factors influence directly or indirectly both individual behaviour and formation of water flow. More important are morphology of zooid, shape of colony and peculiarities of its astogenesis, area and characters of substrate, hydrodynamic regime.