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Cercozoa Superorders
Cercozoa is a phylum of diverse single-celled eukaryotes. They lack shared morphological characteristics at the microscopic level, and are instead defined by molecular phylogenies of rRNA and actin or polyubiquitin. They were the first major eukaryotic group to be recognized mainly through molecular phylogenies. They are the natural predators of many species of microbacteria and Archea. They are closely related to the phylum Retaria, comprising amoeboids that usually have complex shells, and together form a supergroup called Rhizaria. Characteristics The group includes most amoeboids and flagellates that feed by means of filose pseudopods. These may be restricted to part of the cell surface, but there is never a true cytostome or mouth as found in many other protozoa. They show a variety of forms and have proven difficult to define in terms of structural characteristics, although their unity is strongly supported by phylogenetic studies. Diversity Some cercozoans are grouped by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cercomonas
Cercomonads are small flagellates, widespread in aqueous habitats and common in soils. Characteristics The cells are generally around 10 μm in length, without any shell or covering. They produce filose pseudopods to capture bacteria, but do not use them for locomotion, which usually takes place by gliding along surfaces. Most members have two flagella, one directed forward and one trailing under the cell, inserted at right angles near its anterior. The nucleus is connected to the flagellar bases and accompanied by a characteristic paranuclear body. Classification Genetic studies place the cercomonads among the Cercozoa, a diverse group of amoeboid and flagellate protozoans. They are divided into two families. * The Heteromitidae tend to be relatively rigid, and produce only temporary pseudopods. * The Cercomonadidae are more plastic, and when food supplies are plentiful may become amoeboid and even multinucleate. The classification of genera and species continues t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |