Cercomonads are small amoeboflagellates, widespread in aqueous habitats and common in soils.

Characteristics

The cells are generally around 10 μm in length, without any shell or covering. They produce filose pseudopods to capture bacteria, but do not use them for locomotion, which usually takes place by gliding along surfaces. Most members have two flagella, one directed forward and one trailing under the cell, inserted at right angles near its anterior. The nucleus is connected to the flagellar bases and accompanied by a characteristic paranuclear body. [[File:2023_Cercomonad.svg|center|thumb|upright=2|Representation of a cercomonad1. Anterior flagellum 2. Microtubular bands 3. Fibrillar rootlet 4. Golgi apparatus; modifies proteins and sends them out of the cell 5. Microtubule cone 6. Nucleus 7. Nucleolus 8. Endoplasmic reticulum, the transport network for molecules going to specific parts of the cell 9. Extrusome 10. Contractile vacuole, regulates the quantity of water inside a cell 11. Dense granule 12. Mitochondrion, creates ATP (energy) for the cell, tubular cristae 13. Food vacuole 14. Prey (bacteria) 15. Lysosome, holds enzymes 16. Posterior flagellum]]

Classification

Genetic studies place the cercomonads among the Cercozoa, a diverse group of amoeboid and flagellate protozoans. They are divided into two families. The classification of genera and species continues to undergo revision. Some genera have been merged, like Cercomonas and Cercobodo. Others like Helkesimastix, Sainouron and Cholamonas have been moved to Helkesida, while the rest of the family Heteromitidae has been moved to Glissomonadida. Most recently, the family Paracercomonadidae, previously included in this order, has been separated into its own order Paracercomonadida. This change has made Cercomonadidae the only existing family of cercomonads.