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Euglenida A class of mostly unicellular protoctists (including Euglena) that move by means of undulipodia (flagella). Most euglenids are photosynthetic and inhabit fresh water, and in some classification systems are regarded as green algae (phylum Chlorophyta). However, they lack a cell wall, being covered with a proteinaceous pellicle, and some forms are colourless and thus ingest food, since they cannot photosynthesize. Euglenids are sometimes classified as a phylum, Euglenophyta, but they are now more usually included in a larger phylum, Discomitochondria, together with three other groups of organisms, on the basis of a common mitochondrial structure (characterized by disc-shaped cristae) and the absence of sexual reproduction.