Domain Eukaryota
Cercozoa

The Cercozoa are a large group of amoeboid and flagellate Rhizaria.

Though diverse and difficult to describe by structural similarities, genetic studies confirm the unity of this kingdom.

The Cercozoa all engulf their food with filament-supported psuedopodia (filopodia). They never have a cytostome (mouth). The main groups include:

• The Cercomonadida (above) use filopodia for feeding and have two flagella, but move by gliding along surfaces. Complex reproduction. Common in soil and water.
  

• The Silicofilosea (or Euglyphids) (right) assemble silica plates into a shell with a single opening for the filopodia. Common in soil and marshes.

• The Chlorarachniophyta (left) are strange amoebids that link together in multicellular nets. They have chloroplasts bound by four membranes and a vestigal nucleus (all leftovers from an anciently consumed green alga).

• The Nucleohelea have spherical cells attached to stalks and unusual nuclei fibers.
• The Phaeodarea are marine amoebids that produce porous shells made of silica and organic waste clusters.
• The Phytomyxea are parasites of agricultural plants. They have a flagellated stage. Their nuclei make a cross-shape when replicating.
• The Thecofilosea have organic shells. Their classification is uncertain.

Many of these Cercozoan groups were formerly classified with other groups including the Radiolaria, Amoebozoa or Fungi. But genetic research has brought them together into this kingdom.

The unusual structure of shells and organelles in the Cercozoa make them of great interest to researchers studying the endosymbiotic origins of the Eukaryotes.