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By the 1970s, it became usual to require that all taxa be monophyletic (derived from a common ancestor that would also be regarded as protozoan), and holophyletic (containing all of the known descendants of that common ancestor). The taxon 'Protozoa' fails to meet these standards, so grouping protozoa with animals, and treating them as closely ...
Giardia lamblia, an infectious protozoan. Protozoan infections are parasitic diseases caused by organisms formerly classified in the kingdom Protozoa. These organisms are now classified in the supergroups Excavata, Amoebozoa, Harosa (SAR supergroup), and Archaeplastida. They are usually contracted by either an insect vector or by contact with ...
Main article: Human parasite Endoparasites Protozoan organisms Common name of organism or disease Latin name (sorted) Body parts affected Diagnostic specimen Prevalence Source/Transmission (Reservoir/Vector) Granulomatous amoebic encephalitis and Acanthamoeba keratitis (eye infection) Acanthamoeba spp. eye, brain, skin culture worldwide contact lenses cleaned with contaminated tap water ...
These can be categorized into three groups; cestodes, nematodes and trematodes.Examples include: Acanthocephala; Ascariasis (roundworms); Cestoda (tapeworms) including: Taenia saginata (human beef tapeworm), Taenia solium (human pork tapeworm), Diphyllobothrium latum (fish tapeworm) and Echinococcosis (hydatid tapeworm)
Human parasites are divided into endoparasites, which cause infection inside the body, and ectoparasites, which cause infection superficially within the skin. The cysts and eggs of endoparasites may be found in feces , which aids in the detection of the parasite in the human host while also providing the means for the parasitic species to exit ...
Classic examples include interactions between vertebrate hosts and tapeworms, flukes, and those between the malaria-causing Plasmodium species, and fleas. Parasites reduce host fitness by general or specialised pathology, that ranges from parasitic castration to modification of host behaviour.
A typical example of a ciliated microorganism is the Paramecium, a one-celled, ciliated protozoan covered by thousands of cilia. The cilia beating together allow the Paramecium to propel through the water at speeds of 500 micrometers per second.
Microscopic organisms were increasingly constrained in the plant/animal dichotomy. In 1858, the palaeontolgist Richard Owen was the first to define Protozoa as a separate kingdom of eukaryotic organisms, with "nucleated cells" and the "common organic characters" of plants and animals, although he also included sponges within protozoa. [27]