The Cercozoa are a group of protists, including most amoeboids and flagellates that feed by means of filose pseudopods. These may be restricted to part of the cell surface, but there is never a true cytostome or mouth as found in many other protozoa. They show a variety of forms and have proven difficult to define in terms of structural characteristics, although their unity is strongly supported by genetic studies. Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Typical phyla Rhodophyta (red algae) Chromista Heterokontophyta (heterokonts) Haptophyta Cryptophyta (cryptomonads) Alveolates Dinoflagellata Apicomplexa Ciliophora (ciliates) Excavates Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Amoebozoa Choanozoa Many others; classification varies Protists are a heterogeneous group of living things, comprising those eukaryotes which are neither animals, plants, nor fungi. ... Thomas Cavalier-Smith is a professor of evolutionary biology at the University of Oxford, and is winner of the International Prize for Biology 2004 and one of the most notable researchers concerning the relationships, development, and classification of living things. ... Typical phyla Rhodophyta (red algae) Chromista Heterokontophyta (heterokonts) Haptophyta Cryptophyta (cryptomonads) Alveolates Dinoflagellata Apicomplexa Ciliophora (ciliates) Excavates Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Amoebozoa Choanozoa Many others; classification varies Protists are a heterogeneous group of living things, comprising those eukaryotes which are neither animals, plants, nor fungi. ... Amoeba (Chaos diffluens) Foraminiferan shells Heliozoan (Actinophrys sol) Amoeboids are cells that move or feed by means of temporary projections, called pseudopods (false feet). ... Parasitic excavate (Giardia lamblia) Green algae (Chlamydomonas) PROTISTA KINGDOM Flagellates are members of the Protista Kingdom. ... A cytostome or cell mouth is a part of a cell specialized for phagocytosis, usually in the form of a microtubule-supported funnel or groove. ...

The best-known Cercozoa are the euglyphids, filose amoebae with shells of siliceous scales or plates, which are commonly found in soils, nutrient-rich waters, and on aquatic plants. Some other filose amoebae produce organic shells, including the tectofilosids and Gromia. They were formerly classified with the euglyphids as the Testaceafilosia. This group is not monophyletic, but nearly all studied members fall in or near the Cercozoa, related to similarly shelled flagellates. Families Cyphoderiidae Euglyphidae Paulinellidae Trinematidae The euglyphids are a prominent group of filose amoebae that produce shells or tests from siliceous scales, plates, and sometimes spines. ... Families Amphitremidae Chlamydophryidae Psammonobiotidae Pseudodifflugiidae Volutellidae The tectofilosids or amphitremids are a group of filose amoebae with shells. ... Gromia is a widespread genus of marine and freshwater amoeboids, closely resembling some foraminiferans. ...

Another important group placed here are the chlorarachniophytes, strange amoebae that form a reticulating net. They are set apart by the presence of chloroplasts, which apparently developed from an ingested green alga. They are bound by four membranes and still possess a vestigial nucleus, called a nucleomorph. As such, they have been of great interest to researchers studying the endosymbiotic origins of organelles. Genera Chlorarachnion Gymnochlora Lotharella Cryptochlora Chlorarachniophytes are a small group of algae occasionally found in tropical oceans. ... The inside of a chloroplast Chloroplasts are organelles found in plant cells and eukaryotic algae which conduct photosynthesis. ... Divisions Chlorophyta Charophyta Streptophytina (Subdivision) The green algae are the large group of algae from which the embryophytes (higher plants) emerged. ...

Other notable cercozoans include the cercomonads, which are common soil flagellates. Two groups traditionally considered heliozoa, the dimorphids and desmothoracids, belong here. Recently the marine Phaeodarea have also been included. The Cercozoa are closely related to the Foraminifera and Radiolaria, amoeboids that usually have complex shells, and together with them form a supergroup called the Rhizaria. Their exact composition and relationships are still being worked out. The main groups of core Cercozoa are the following: Genera Cercomonadidae    Cercomonas    Helkesimastix Heteromitidae    Heteromita    Protaspis    Allantion    Sainouron    Cholamonas    Katabia Cercomonads are small flagellates, widespread in aqueous habitats and especially common in soils. ... Heliozoa, or sun animalcules, are roughly spherical amoeboids with many stiff, microtubule-supported projections called axopods radiating outward from the cell surface. ... The dimorphids are a small group of flagellate heliozoa. ... Genera Clathrulina Hedriocystis Cienkowskya Penardiophrys Actinosphaeridium The desmothoracids are a group of heliozoan protists, usually sessile and found in freshwater environments. ... The Phaeodarea are a group of amoeboid protozoa. ... Orders Allogromiida Carterinida Fusulinida - extinct Globigerinida Involutinida Lagenida Miliolida Robertinida Rotaliida Silicolocunida Spirillinida Textulariida The Foraminifera, or forams for short, are a large group of amoeboid protists with reticulating pseudopods, fine strands that branch and merge to form a dynamic net. ... Possible classes Polycystinea Acantharea Taxopodea Radiolaria are amoeboid protozoa that produce intricate mineral skeletons, typically with a central capsule dividing the cell into inner and outer portions, called endoplasm and ectoplasm. ... The Rhizaria are a major line of protists. ...

• Class Chlorarachnea (chlorarachniophytes)
• Class Spongomonadea
• Class Proteomyxidea - desmothoracids, dimorphids, gymnophryids, etc.
• Class Sarcomonadea - cercomonads
• Class Imbricatea - euglyphids and thaumatomonads
• Class Thecofilosea - tectofilosids and cryomonads
• Class Phaeodarea

Some other smaller groups are of uncertain placement. In addition two groups of parasites, the Phytomyxea and Ascetosporea, and the shelled amoeba Gromia may also be classified as Cercozoa, although some trees place them closer to the Foraminifera. Genera Chlorarachnion Gymnochlora Lotharella Cryptochlora Chlorarachniophytes are a small group of algae occasionally found in tropical oceans. ... Genera Clathrulina Hedriocystis Cienkowskya Penardiophrys Actinosphaeridium The desmothoracids are a group of heliozoan protists, usually sessile and found in freshwater environments. ... The dimorphids are a small group of flagellate heliozoa. ... The gymnophryids are a small group of amoeboids that lack shells and produce thin, reticulose pseudopods. ... Genera Cercomonadidae    Cercomonas    Helkesimastix Heteromitidae    Heteromita    Protaspis    Allantion    Sainouron    Cholamonas    Katabia Cercomonads are small flagellates, widespread in aqueous habitats and especially common in soils. ... Families Cyphoderiidae Euglyphidae Paulinellidae Trinematidae The euglyphids are a prominent group of filose amoebae that produce shells or tests from siliceous scales, plates, and sometimes spines. ... Families Amphitremidae Chlamydophryidae Psammonobiotidae Pseudodifflugiidae Volutellidae The tectofilosids or amphitremids are a group of filose amoebae with shells. ... The Phaeodarea are a group of amoeboid protozoa. ... Genera Lignieria Membranosorus Octomyxa Phagomyxa Plasmodiophora Polymyxa Sorodiscus Sorosphaera Spongospora Tetramyxa Woronina The Phytomyxea are a group of protists that are parasites of plants. ... Genera Haplosporidiidae    Haplosporidium    Minchina    Urosporidium Paramyxidae    Marteilia    Paramartelia    Paramyxa The Ascetosporea are a group of protists that are parasites of animals, especially marine invertebrates. ... Gromia is a widespread genus of marine and freshwater amoeboids, closely resembling some foraminiferans. ...

References

• Cavalier-Smith, T. (1998). A revised six-kingdom system of life. Biological Reviews of the Cambridge Philosophical Society 73: 203-266.
• Cavalier-Smith, T. and Chao, E.E. (2003). Phylogeny and Classification of Phylum Cercozoa (Protozoa). Protist 154 (3-4): 341-358.