ABSTRACT
Protozoans are numerically and functionally important in most benthic habitats. Unfortunately, taxonomic and ecological studies of these organisms have lagged behind those of larger organisms because of difficulties in extraction and a lack of taxonomic expertise. The silica gel-sorbitol technique has successfully extracted a wide variety of protists from tropical muds, detrital carbonates, and quartz, and carbonate sands. Either of two procedures may be used to determine recovery efficiency: the cumulative yield method or the cell addition technique. The cumulative yield method is the simplest: repeat the extraction-centrifugation procedure until no further cells are harvested. The alternative procedure is to add a known number of various protists grown in laboratory culture. A great variety of culturing procedures may be used particularly for large ciliates, foraminifera, amoebae, and flagellates. A listing of research centers from where cultures may be obtained is provided by Cowling.
