Cercozoa

Cercozoa is a diverse clade of single-celled eukaryotes within the Rhizaria that includes a wide range of shapes and lifestyles. Most cercozoans are heterotrophic and feed using filamentous, threadlike pseudopods, or filose pseudopodia, which they extend to capture prey such as bacteria and small algae. The group comprises both naked and testate (shelled) forms and combines amoeboid and flagellate morphologies, reflecting a broad spectrum of cellular organization.

Ecologically, cercozoans are ubiquitous in soils, freshwaters, and oceans. They play key roles in microbial food webs as bacterivores, algivores, and predators of other protists, contributing to nutrient cycling and energy flow. Some cercozoans form symbiotic relationships with other organisms, while a few lineages are plant or animal parasites.

In terms of phylogeny, Cercozoa is a major clade within Rhizaria and includes several lineages such as the chlorarachniophytes (photosynthetic cercozoans with plastids derived from green algae and a nucleomorph), cercomonads (often free-living bacterivores), and plasmodiophorids (notably plant parasites like Plasmodiophora and Spongospora). Taxonomic arrangements continue to evolve with molecular data, and relationships among subgroups are an active area of study.

Cercozoa are important for understanding protist diversity, ecology, and the evolution of complex cell plans within Rhizaria. Their wide distribution and functional roles make them a common subject in studies of microbial communities and environmental monitoring.