Filozoa

For an explanation of very similar terms, see Holozoa.

The Filozoa are a monophyletic grouping within the Opisthokonta. They include animals and their nearest unicellular relatives (organisms which are more closely related to animals than to fungi or Mesomycetozoa).^[1]

Filozoa Temporal range: 760–0 Ma Pha. Proterozoic Archean Had.
Orange elephant ear sponge, Agelas clathrodes, in foreground. Two corals in the background: a sea fan, Iciligorgia schrammi, and a sea rod, Plexaurella nutans.
Scientific classification
Domain:	Eukaryota
Clade:	Amorphea
Clade:	Obazoa
Clade:	Opisthokonta
Clade:	Holozoa
Clade:	Filozoa Shalchian-Tabrizi et al., 2008
Subgroups
Filasterea Choanozoa Choanoflagellatea Animalia

Three groups are currently included within the clade Filozoa:

• Group Filasterea - recently^[when?] described to include the genera Ministeria and Capsaspora
• Group Choanoflagellatea - collared flagellates
• Kingdom Animalia - the group of which all extant animals belong to

Etymology

The name Filozoa originates from the Latin word filum meaning "thread" and the Greek word zōion meaning "animal".

Phylogeny

Below is a phylogenetic tree of Filozoa and the groups most closely related to the Filozoa :^[2][3][4][5]

Opisthokonta	Holomycota Cristidiscoidea Fonticulida Nucleariida Fungi/ BCG2 True Fungi Aphelida BCG1 Rozellomyceta/ Rozella Namako-37 Microsporidia Cryptomycota Opisthosporidia Holozoa Ichthyosporea Pluriformea Syssomonas Corallochytrium Filozoa Filasterea Choanozoa Choanoflagellatea Animalia 950 mya 1100 mya
1300 mya

Characteristics

The ancestral opisthokont cell is assumed to have possessed slender filose (thread-like) projections or 'tentacles'. In some opisthokonts (Mesomycetozoa and Corallochytrium) these were lost. They are retained in Filozoa, where they are simple and non-tapering, with a rigid core of actin bundles (contrasting with the flexible, tapering and branched filopodia of nucleariids and the branched rhizoids and hyphae of fungi). In choanoflagellates and in the most primitive animals, namely sponges, they aggregate into a filter-feeding collar (made from microvilli, that are also made from actin) around the cilium or flagellum; this is thought to be an inheritance from their most recent common filozoan ancestor.^[1]