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Holozoan
Holozoa () is a clade of organisms that includes animals and their closest unicellular, single-celled relatives, but excludes fungi and all other organisms. Together they amount to more than 1.5 million species of purely heterotrophic organisms, including around 300 unicellular organism, unicellular species. It consists of various subgroups, namely Metazoa (or animals) and the protists Choanoflagellata, Filasterea, Pluriformea and Ichthyosporea. Along with fungi and some other groups, Holozoa is part of the Opisthokonta, a supergroup (biology), supergroup of eukaryotes. Choanofila was previously used as the name for a group similar in composition to Holozoa, but its usage is discouraged now because it excludes animals and is therefore paraphyletic. The holozoan protists play a crucial role in understanding the evolutionary steps leading to the emergence of multicellular animals from single-celled ancestors. Recent genomic studies have shed light on the evolutionary relationships b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protist
A protist ( ) or protoctist is any eukaryotic organism that is not an animal, land 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 land plants, animals, and fungi. Protists were historically regarded as a separate taxonomic kingdom known as Protista or Protoctista. With the advent of phylogenetic analysis and electron microscopy studies, the use of Protista as a formal taxon was gradually abandoned. In modern classifications, protists are spread across several eukaryotic clades called supergroups, such as Archaeplastida ( photoautotrophs that includes land plants), SAR, Obazoa (which includes fungi and animals), Amoebozoa and " Excavata". Protists represent an extremely large genetic and ecological diversity in all environments, including extreme habitats. Their diversity, larger than for all other eukaryotes, has only been discovered in rece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syssomonas
''Syssomonas'' is a monotypic genus of unicellular flagellated protists containing the species ''Syssomonas multiformis''. It is a member of Pluriformea inside the lineage of Holozoa, a clade containing animals and their closest protistan relatives. It lives in freshwater habitats. It has a complex life cycle that includes unicellular amoeboid and flagellated phases, as well as multicellular aggregates, depending on the growth medium and nutritional state. Life stages ''Syssomonas multiformis'' is a species of unicellular protists with naked cells (lacking any Test (biology), shell or scales) that presents with a variety of life forms during their complex Biological life cycle, life cycle. These forms include: round flagellate cells (7–14 μm in diameter) with one posterior (anatomy), posterior flagellum, amoeboflagellate (i.e. with both flagella and pseudopodia) cells, amoeboid non-flagellar cells, and spherical microbial cyst, cysts. They can also form clusters of multiple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bicellum Brasieri
''Bicellum'' is a genus of fossil holozoans containing the single species ''Bicellum brasieri''. It is one billion years old and could be the oldest example of complex multicellularity in the evolutionary lineage leading to the animals, and has been described as bridging "the gap between the very first living creatures — single-celled organisms — and more complex multicellular life." It was discovered in 2021, and is posthumously named after the late Martin Brasier, a paleontologist who was a co-author of the paper that first described it. Fossil site ''Bicellum'' was found in sediments from the Diabaig Formation in Loch Torridon, Scotland. The Diabaig Formation, considered to represent an ancient lake deposit, was already known to preserve the first non-marine eukaryote The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corallochytrium
''Corallochytrium'' belongs to the class of Corallochytrea. It is either a sister group to Ichthyosporea together forming Teretosporea, or a sister group to '' Syssomonas'' together forming Pluriformea. ''Corallochytrium limacisporum'' is the only species of Corallochytrium known so far. It was first discovered and named in the Arabian Sea’s coral lagoons by Kaghu-Kumar in 1987. It was first thought to be a member of the fungi-like thraustochytrids, however, this was later disproven due to Corallochytriums lack of cilia and sagenogenetosome. Little research has been done on the life cycle or morphology. Most research concerning this genus has been done to uncover the evolution of animals and fungi, as Corallochytrium possess both animal and fungal enzymatic trademarks (C-14 reductase and α-AAR respectively). Etymology The genus name is derived from the habitat in which it was first found: coral reef lagoons. The single species name is derived from the limax-shaped (slug- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Choanozoa
Choanozoa is a clade of opisthokont eukaryotes consisting of the choanoflagellates (Choanoflagellatea) and the animals (Animalia, Metazoa). The sister-group relationship between the choanoflagellates and animals has important implications for the origin of the animals. The clade was identified in 2015 by Graham Budd and Sören Jensen, who used the name Apoikozoa. The 2018 revision of the classification first proposed by the International Society of Protistologists in 2012 recommends the use of the name Choanozoa. Introduction A close relationship between choanoflagellates and animals has long been recognised, dating back at least to the 1840s. A particularly striking and famous similarity between the single-celled choanoflagellates and multicellular animals is provided by the collar cells of sponges and the overall morphology of the choanoflagellate cell. The relationship has since been confirmed by multiple molecular analyses. This proposed homology was however thrown into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capsaspora
''Capsaspora'' is a monotypic genus of protists containing the single species ''Capsaspora owczarzaki. C. owczarzaki'' is a single-celled eukaryote that occupies a key phylogenetic position in our understanding of the origin of animal multicellularity, as one of the closest unicellular relatives to animals. It is, together with '' Ministeria vibrans'', a member of the Filasterea clade. This amoeboid protist has been pivotal to unraveling the nature of the unicellular ancestor of animals, which has been proved to be much more complex than previously thought. Description ''C. owczarzaki'' was originally described as an amoeba-like “symbiont” of the fresh-water snail '' Biomphalaria glabrata''. The amoebae were obtained from the haemolymph Hemolymph, or haemolymph, is a fluid, similar to the blood in invertebrates, that circulates in the inside of the arthropod's body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which hemo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryotes
The eukaryotes ( ) constitute the domain of Eukaryota or Eukarya, organisms whose cells have a membrane-bound nucleus. All animals, plants, fungi, seaweeds, and many unicellular organisms are eukaryotes. They constitute a major group of life forms alongside the two groups of prokaryotes: the Bacteria and the Archaea. Eukaryotes represent a small minority of the number of organisms, but given their generally much larger size, their collective global biomass is much larger than that of prokaryotes. The eukaryotes emerged within the archaeal kingdom Promethearchaeati and its sole phylum Promethearchaeota. This implies that there are only two domains of life, Bacteria and Archaea, with eukaryotes incorporated among the Archaea. Eukaryotes first emerged during the Paleoproterozoic, likely as flagellated cells. The leading evolutionary theory is they were created by symbiogenesis between an anaerobic Promethearchaeati archaean and an aerobic proteobacterium, which form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supergroup (biology)
A supergroup or super-group, in systematics, is a large group of organisms that monophyletic, share one common ancestor and have important defining characteristics. It is an informal, mostly arbitrary rank in biology, biological Taxonomy (biology), taxonomy that is often greater than phylum or kingdom (biology), kingdom, although some supergroups are also treated as phylum, phyla. Eukaryotic supergroups Since the decade of the 2000s, the Eukaryote#Phylogeny, eukaryotic tree of life (abbreviated as eToL) has been divided into 5–8 major groupings called 'supergroups'. These groupings were established after the idea that only monophyletic groups should be accepted as ranks, as an alternative to the use of paraphyletic kingdom Protista. In the early days of the eToL six traditional supergroups were considered: Amoebozoa, Opisthokonta, "Excavata", Archaeplastida, "Chromalveolata" and Rhizaria. Since then, the eToL has been rearranged profoundly, and most of these groups were found as pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metazoa
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia (). With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development. Animals form a clade, meaning that they arose from a single common ancestor. Over 1.5 million living animal species have been described, of which around 1.05 million are insects, over 85,000 are molluscs, and around 65,000 are vertebrates. It has been estimated there are as many as 7.77 million animal species on Earth. Animal body lengths range from to . They have complex ecologies and interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology, and the study of animal behaviour is known as ethology. The animal kingdom is divided into five major clades, namely Porifera, Ctenophora, Placozoa, C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unicellular Organism
A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms and eukaryotic organisms. Most prokaryotes are unicellular and are classified into bacteria and archaea. Many eukaryotes are multicellular, but some are unicellular such as protozoa, unicellular algae, and unicellular fungi. Unicellular organisms are thought to be the oldest form of life, with early organisms emerging 3.5–3.8 billion years ago. Although some prokaryotes live in colonies, they are not specialised cells with differing functions. These organisms live together, and each cell must carry out all life processes to survive. In contrast, even the simplest multicellular organisms have cells that depend on each other to survive. Most multicellular organisms have a unicellular life-cycle stage. Gametes, for example, are reprodu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterotrophic
A heterotroph (; ) is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary, secondary and tertiary consumers, but not producers. Living organisms that are heterotrophic include all animals and fungi, some bacteria and protists, and many parasitic plants. The term heterotroph arose in microbiology in 1946 as part of a classification of microorganisms based on their type of nutrition. The term is now used in many fields, such as ecology, in describing the food chain. Heterotrophs occupy the second and third trophic levels of the food chain while autotrophs occupy the first trophic level. Heterotrophs may be subdivided according to their energy source. If the heterotroph uses chemical energy, it is a chemoheterotroph (e.g., humans and mushrooms). If it uses light for energy, then it is a photoheterotroph (e.g., green non-sulfur bacteria). Heterotrop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
