Members of the Cryomonadida are single-celled organisms that are surrounded by a shell comprising layers of organic material. They possess two unequally long flagella, and a single nucleus with a distinct nucleolus. They have a laterally located cytostome, from which pseudopodia arise.
The order Cryomonadida was erected in 1993 for the genus Cryothecomonas. In 2005, Sina Adl et al. did not include the order in their classification, but placed the genus incertae sedis among the Cercozoa. It became clear, however, that other genera, and taxa known only from environmental DNA, belonged in this group, and so in 2008 Jan Pawlowski placed the Cryomonadida as part of the core Cercozoa.
The following genera are included:
- Thomas Cavalier-Smith & Ema E.-Y. Chao (2003). "Phylogeny and classification of phylum Cercozoa (Protozoa)". Protist 154 (3-4): 341–358. doi:10.1078/143446103322454112. PMID 14658494.
- Sina M. Adl, Alastair G. B. Simpson, Mark A. Farmer, Robert A. Andersen, O. Roger Anderson et al. (2005). "The new higher level classification of eukaryotes with emphasis on the taxonomy of protists". Journal of Eukaryotic Microbiology 52 (5): 399–451. doi:10.1111/j.1550-7408.2005.00053.x. PMID 16248873.
- Jan Pawlowsk (2008). "The twilight of Sarcodina: a molecular perspective on the polyphyletic origin of amoeboid protists" (PDF). Protistology 5 (4): 281–302.
- Mona Hoppenrath & Brian S. Leander (2006). "Ebriid phylogeny and the expansion of the Cercozoa" (PDF). Protist 157: 279–290. doi:10.1016/j.protis.2006.03.002. PMID 16730229.