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Many protist species can switch between asexual reproduction and sexual reproduction involving meiosis and fertilization. [6] In contrast to the cells of prokaryotes, the cells of eukaryotes are highly organised. Plants, animals and fungi are usually multi-celled and are typically macroscopic. Most protists are single-celled and microscopic.
In the Volvocine lineage the species of interest is Gonium. This 8- or 16-cell colony represents one of the first steps to true multicellularity, [49] presumed to have evolved from the unicellular common ancestor earlier than other Volvocine algae. [50] It is also the first to show cell differentiation. [26]
[4] [5] Although most protists are unicellular, there is a considerable range of multicellularity amongst them; some form colonies or multicellular structures visible to the naked eye. The term 'protist' refers to all eukaryotes that are not animals, plants or fungi, the three traditional eukaryotic kingdoms.
Reproduction in Protozoa can be sexual or asexual. [38] Most Protozoa reproduce asexually through binary fission. [39] Many parasitic Protozoa reproduce both asexually and sexually. [38] However, sexual reproduction is rare among free-living protozoa and it usually occurs when food is scarce or the environment changes drastically. [40]
Protists are a large group of diverse eukaryotic microorganisms, mainly unicellular animals and plants, that do not form tissues. [8] The earliest eukaryotes were likely protists. Mating and sexual reproduction are widespread among extant eukaryotes including protists such as Paramecium and Chlamydomonas.
Protists reproduce asexually or sexually. If the protists reproduce asexually, they do so through binary fission, multiple fission, budding, and fragmentation. If the protists reproduce sexually, they do so through a syngamy process where there is a fusion of the gametes. If this occurs in an individual it is recognized as autogamy.
Memórias do Instituto Oswaldo Cruz, 1909-, Brazil. Some societies: Society of Protozoloogists, 1947-2005, USA (renamed International Society of Protistologists, 2005-), with many affiliates; [12] International Society for Evolutionary Protistology, 1975, USA. [13] Protistology UK (previously British Society for Protist Biology) [14]
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.