Protoctista

(redirected from protoctists)
Also found in: Thesaurus, Medical.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.Protoctista - in most modern classifications, replacement for the Protista; includes: Protozoa; Euglenophyta; Chlorophyta; Cryptophyta; Heterokontophyta; Rhodophyta; unicellular protists and their descendant multicellular organisms: regarded as distinct from plants and animals
protoctist order - the order of protoctists
protoctist - any of the unicellular protists
division Protista, Protista - eukaryotic one-celled living organisms distinct from multicellular plants and animals: protozoa, slime molds, and eukaryotic algae
protoctist family - any of the families of Protoctista
protoctist genus - any genus of Protoctista
phylum Protozoa, Protozoa - in some classifications considered a superphylum or a subkingdom; comprises flagellates; ciliates; sporozoans; amoebas; foraminifers
division Heterokontophyta, Heterokontophyta - algae having chlorophyll a and usually c, and flagella of unequal lengths; terminology supersedes Chrysophyta in some classifications
Chrysophyta, division Chrysophyta - mostly freshwater eukaryotic algae having the chlorophyll masked by brown or yellow pigment; yellow-green and golden-brown algae and diatoms: Xanthophyceae, Chrysophyceae, Bacillariophyceae; some classification systems superseded or subsumed by Heterokontophyta
division Euglenophyta, Euglenophyta - free-swimming flagellate algae
Chlorophyta, division Chlorophyta - large division of chiefly freshwater eukaryotic algae that possess chlorophyll a and b, store food as starch, and cellulose cell walls; classes Chlorophyceae, Ulvophyceae, and Charophyceae; obviously ancestral to land plants
division Rhodophyta, Rhodophyta - lower plants; mostly marine and littoral eukaryotic algae
Cryptophyta, phylum Cryptophyta - a phylum in the kingdom Protoctista
kingdom - the highest taxonomic group into which organisms are grouped; one of five biological categories: Monera or Protoctista or Plantae or Fungi or Animalia
References in periodicals archive ?
2005) as precursor protoctists of ciliated animal cells and plant sperm.
Although bacteria can exchange genetic material and unicellular protoctists can merge to form larger cells, in neither of these cases is the exchange of genes necessary for reproduction to occur.
As Case noted, attempted reconciliation of five Kingdoms (Bacteria, Protoctists, Animals, Plants, Fungi) with three Domains (Bacteria, Archaea, Eucarya) resulted in a "compromise" of six kingdoms (Archaebacteria, Eubacteria, Protista, Fungi, Plantae, Animalia)--an outcome that does not fully represent the intent of either the five-kingdom or three-domain system.
Anthropogenic Natural Unintentional Gas-to-particle conversions Internal combustion engines Forest fires Power plants Volcanoes (hot lava) Incinerators Viruses Jet engines Biogenic magnetite: magnetotactic Metal fumes (smelting, bacteria protoctists, mollusks, welding, etc.
The five kingdoms system identifies five categories of organisms as rational kingdom divisions: bacteria (the prokaryotic or nucleus-lacking microbes), protoctists (algae, slime molds, and other nucleated eukaryotic organisms formed by symbiosis from bacteria), fungi (mushrooms, molds, and yeasts, all of which reproduce by spores), plants (organisms that develop from spores and embryos retained by the mother's tissue), and animals (organisms that develop from eggs fertilized by sperm).
protoctists, and bacteria], animals may be defined as multicellular,
For decades, most biologists accepted the classification of all life into five kingdoms: Bacteria (or Monera), Protoctists (protists and their macroscopic relatives), Animals, Plants, and Fungi (Figure 1).
Only some forms of bacteria, some protoctists (all are algae), and plants can perform photosynthesis.
This build-up of CO2 may have been the cause of the apparent release of calcium carbonate during the Cretaceous period in shallow sea areas where many corals and mollusks lived, all in a symbiotic relationship with photosynthetic protoctists.
Dead plants are colonized by several types of organism, including bacteria, fungi, protoctists, and small animals such as nematodes.
The silicoflagellates are medium-sized flagellated protoctists (20-70 microns), with a thin membrane, numerous chromatophores and a highly distinctive internal reticulate skeleton, generally showing four-fold or six-fold symmetry.
Various heterotrophic protoctists also produce external skeletons that persist after the death of the more active part.