Chapter 10 – Photosynthetic Euglenoids

Euglenoids form a diverse group of eukaryotic organisms that may have arisen a billion years or more before the origins of plants and animals. They are largely unicellular flagellates with only one genus, and they form colonies. There are nearly 2,900 nominal species for the major photosynthetic taxa, but, of these, only about 800 are accepted as taxonomically valid. Modern phylogenetics has caused numerous changes in euglenoid taxonomy, which keeps the number of accepted species in constant transition. The majority of photosynthetic taxa live in freshwater, and only a few taxa are found in seas and oceans. The most common habitats are eutrophic small water bodies (ditches, canals, ponds). This chapter provides a classification of the freshwater representatives of the Euglenophyceae, with descriptions of their morphology, reproduction, and ecology, as well as color photographs and line drawings of the taxa and a key to genera.