 Protist diversity is high in oceans, deep sea-vents, river sediment and an acidic river, suggesting that many eukaryotic microbial communities may yet be discovered.The fungi have several unicellular species, such as baker's yeast ("Saccharomyces cerevisiae") and fission yeast ("Schizosaccharomyces pombe").Some fungi, such as the pathogenic yeast "Candida albicans", can undergo phenotypic switching and grow as single cells in some environments, and filamentous hyphae in others.