Why Euglena are fascinating!! They really are!!!

Euglena are amazing creatures. In the 1800s scientists asked if these were plant or animal. Now we ask are they algae or protozoans.
The core genome of Euglena, surprisingly for a genus classified as algae, is most closely related to the pathogenic protozoans, Trypanosomes and Leishmania. We consider Euglena to be algae because the can live autotrophically via their chloroplasts. But these chloroplasts are actually just a remnant of a green algae endosymbiont that once lived in the hosting protozoan. Euglena also have in their genomes genes from green algae and red algae- these too are genetic elements that were transferred to the protozoan from the endosymbiotic algae approximately 1 billion years ago.
Sources:
Oneill, EC, M Trick, B Henrissat, RA Field (2015). Euglena in time: Evolution, control of central metabolic processes an multi-domain proteins in carbohydrate and natural product biochemistry. Perspect. Sci., 6, 84-85.
Leedale GF (1964). Pellicle structure in Euglena. Brit. Phycol. Bull. 2, 291-306.
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