Colponemids are flagellated unicellular protists, 8 to 30 μm long, with rounded cell bodies that bear two heterodynamic flagella for rapid swimming.

[4] As many basal eukaryotes, they present a ventral groove for feeding, tiny in Loeffela, substantial in Palustrimonas[4] and absent in Acavomonas.

[1] They are obligate eukaryovores or eukaryotrophs, free-living predators that feed on other microscopic eukaryotes by capturing and ingesting entire cells.

[3] Myzozoa (apicomplexans & dinoflagellates) Neocolponema Palustrimonas Ciliophora (ciliates) Acavomonas Colponema Loeffela Colponemids are not a clade, i.e. do not form an independent evolutionary lineage within eukaryotes.

In addition, they possibly constitute the evolutionary link to more basal protists with ventral grooves used in feeding, i.e. 'excavates' (such as metamonads, jakobids and malawimonads).

[3] In 2023, three more genera were added to Colponemida: newly described Loeffela and Neocolponema, together with the previously unsequenced genus Palustrimonas, without their inclusion in new phyla.