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A protist (/ ˈ p r oʊ t ɪ s t / PROH-tist) or protoctist is any eukaryotic organism that is not an animal, plant, or fungus.Protists do not form a natural group, or clade, but are a paraphyletic grouping of all descendants of the last eukaryotic common ancestor excluding plants, animals, and fungi.
Some modern authors prefer to exclude multicellular organisms from the traditional definition of a protist, restricting protists to unicellular organisms. [9] [10] This more constrained definition excludes all brown, the multicellular red and green algae, and, sometimes, slime molds (slime molds excluded when multicellularity is defined as ...
Protists are distributed across all major groups of eukaryotes, including those that contain multicellular algae, green plants, animals, and fungi. If photosynthetic and fungal protists are distinguished from protozoa, they appear as shown in the phylogenetic tree of eukaryotic groups.
Physarum polycephalum, an acellular [1] slime mold or myxomycete popularly known as "the blob", [2] is a protist with diverse cellular forms and broad geographic distribution. The “acellular” moniker derives from the plasmodial stage of the life cycle : the plasmodium is a bright yellow macroscopic multinucleate coenocyte shaped in a ...
Although protist flagella have a diversity of forms and functions, [11] two large families, flagellates and ciliates, can be distinguished by the shape and beating pattern of their flagella. [ 2 ] In the phylogenetic tree on the right, aquatic organisms (living in marine, brackish, or freshwater environments) have their branches drawn in blue ...
Coenocyte of Sphaeroforma arctica Botrydium, showing a coenocytic body. A coenocyte (/ ˈ s iː n ə ˌ s aɪ t /) is a multinucleate cell which can result from multiple nuclear divisions without their accompanying cytokinesis, in contrast to a syncytium, which results from cellular aggregation followed by dissolution of the cell membranes inside the mass. [1]
Foraminifera (/ f ə ˌ r æ m ə ˈ n ɪ f ə r ə / fə-RAM-ə-NIH-fə-rə; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of Rhizarian protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly an external shell (called a "test") of diverse forms and materials.
Spirostomum is a genus of ciliated protists in the class Heterotrichea.It is known for being very contractile. [5] Having been first identified by Christian Gottfried Ehrenberg in 1834, further research has identified eight additional true morphospecies.