Euglenophyta
Euglenophyta include mostly unicellular flagellates (Figure 1.39) although colonial species are common. They are widely distributed, occurring in freshwater, brackish and marine waters, most soils, and mud. They are especially abundant in highly heterotrophic environments. The flagella arise from the bottom of a cavity called reservoir, located in the anterior end of the cell. Cells can also ooze their way through mud or sand by a process known as metaboly, a series of flowing movements made possible by the presence of the pellicle, a proteinaceous wall which lies inside the cytoplasm. The pellicle can have a spiral construction and can be ornamented. The members of this division share their pigmentation with prochlorophytes, green algae, and land plants, because they have chlorophylls a and b, β- and γ-carotenes, and xanthins. However, plastids could be colorless or absent in some species. As in the Dinophyta the chloroplast envelope consists of three membranes. Within the chloroplasts, the thylakoids are usually in groups of three, without a girdle lamella and pyrenoids may be present. The chloroplast DNA occurs as a fine skein of tiny granules.