Filozoa
Encyclopedia
The Filozoa are a monophyletic grouping within the Opisthokonta. They include animal
s along with their nearest unicellular relatives (those organisms which are more closely related to animals than to fungi or Mesomycetozoa).
Three groups are currently assigned to the clade
Filozoa:
) 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 rhizoid
s and hypha
e of fungi). In choanoflagellates and in the most primitive animals, namely sponges, they aggregate into a filter-feeding collar around the cilium
or flagellum
; this is thought to be an inheritance from their most recent common filozoan ancestor.
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
s along with their nearest unicellular relatives (those organisms which are more closely related to animals than to fungi or Mesomycetozoa).
Three groups are currently assigned to the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
Filozoa:
- ClassClass (biology)In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...
FilastereaFilastereaFilasterea is a grouping that includes Ministeria and Capsaspora....
– recently erected to house the generaGeneraGenera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
MinisteriaMinisteriaMinisteria is a small single-celled eukaryote which feeds on bacteria. Although it is an opisthokont, it seems not to fit in any of the established opisthokont lineages such as choanoflagellates or animals. It might form a group with Capsaspora, another opisthokont of uncertain placement....
and CapsasporaCapsasporaCapsaspora is a single-celled eukaryote which is a symbiont in the haemolymph of the tropical freshwater snail Biomphalaria glabrata.- Taxonomy :... - ClassClass (biology)In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...
Choanoflagellatea – 'collared' flagellateFlagellateFlagellates are organisms with one or more whip-like organelles called flagella. Some cells in animals may be flagellate, for instance the spermatozoa of most phyla. Flowering plants do not produce flagellate cells, but ferns, mosses, green algae, some gymnosperms and other closely related plants...
s - KingdomKingdom (biology)In biology, kingdom is a taxonomic rank, which is either the highest rank or in the more recent three-domain system, the rank below domain. Kingdoms are divided into smaller groups called phyla or divisions in botany...
Animalia or Metazoa – animals
Cladogram
Characteristics
The ancestral opisthokont cell is assumed to have possessed slender filose (thread-like) projections or 'tentacles'. In some opisthokonts (Mesomycetozoa and CorallochytriumCorallochytrium
Corallochytrium is a single-celled eukaryote which was found in coral reef lagoons of the Lakshadweep islands of the Arabian sea. Although it is an opisthokont, its closest relatives in that group are not clear. For example, it is not clear whether it is more closely related to animals or...
) these were lost. They are retained in Filozoa, where they are simple and non-tapering, with a rigid core of actin
Actin
Actin is a globular, roughly 42-kDa moonlighting protein found in all eukaryotic cells where it may be present at concentrations of over 100 μM. It is also one of the most highly-conserved proteins, differing by no more than 20% in species as diverse as algae and humans...
bundles (contrasting with the flexible, tapering and branched filopodia
Filopodia
Filopodia are slender cytoplasmic projections that extend beyond the leading edge of lamellipodia in migrating cells. They contain actin filaments cross-linked into bundles by actin-binding proteins, e.g. fascin and fimbrin. Filopodia form focal adhesions with the substratum, linking it to the...
of nucleariids and the branched rhizoid
Rhizoid
Rhizoids are thread-like growths from the base or bottom of a plant, found mainly in lower groups such as algae, fungi, bryophytes and pteridophytes, that function like roots of higher plants ....
s and hypha
Hypha
A hypha is a long, branching filamentous structure of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or...
e of fungi). In choanoflagellates and in the most primitive animals, namely sponges, they aggregate into a filter-feeding collar around the cilium
Cilium
A cilium is an organelle found in eukaryotic cells. Cilia are slender protuberances that project from the much larger cell body....
or flagellum
Flagellum
A flagellum is a tail-like projection that protrudes from the cell body of certain prokaryotic and eukaryotic cells, and plays the dual role of locomotion and sense organ, being sensitive to chemicals and temperatures outside the cell. There are some notable differences between prokaryotic and...
; this is thought to be an inheritance from their most recent common filozoan ancestor.