Parasitism
A close, harmful relationship where one organism exploits another.
Soebe · CC BY-SA 3.0
Parasitism is a close relationship where one organism, the parasite, lives on or inside another organism, the host, causing it some harm.[1] Unlike predators, parasites are usually much smaller than their hosts and do not kill them, often living in or on them for an extended period.[2] The Australian Society of Parasitology notes that parasitism is a form of symbiosis, an intimate relationship between two different species.[3]
Quick Facts
- Key classification axis
- invasiveness: endoparasite vs. ectoparasite
Facts from the source article.
Key facts and history
In 1681, Antonie van Leeuwenhoek observed Giardia lamblia with his microscope, and Francesco Redi described internal and external parasites including sheep liver fluke and ticks.[4] The Australian Society of Parasitology states that parasitism must have arisen very early in the history of life on Earth.[3] Parasites greatly outnumber free-living animals, both in individuals and species, making parasitism an evolutionarily advantageous lifestyle.[3] Parasitology focuses on protozoa, helminths, and arthropods that are obligate parasites of host animals.[3]
The English language first employed the term "parasite" in 1539, deriving it from the Medieval French word "parasite".[5] A parasite that is obligate requires its host to finish its life cycle, whereas a facultative one can survive without that dependency.[6] Researchers categorize parasites using multiple, sometimes overlapping, systems that consider how they interact with hosts and the nature of their life cycles.[6]
What the research sources say
The Australian Society of Parasitology explains that parasitism may lead to disease, but not always.[3] It notes that while a parasite is often claimed to damage its host, in practice this can be impossible to establish because so little is known about most symbiotic relationships.[3] The same source describes that when multiple hosts are involved, the definitive host is where the adult or sexual form occurs, while the intermediate host supports non-sexual or larval stages.[3] Intermediate hosts that carry the infective stage are termed vectors, either mechanical or cyclical.[3]
The Australian Society of Parasitology's helminth resource states that adult worms infect definitive hosts where sexual development occurs, while larval stages may be free-living or parasitize invertebrate vectors.[7]
References
- Wikipedia, "Parasitism" (CC BY-SA 4.0), which cites: "About Parasites", Parasites, 14 November 2024; Poulin 2007 (original not read by us) en.wikipedia.org
- Wikipedia, "Parasitism" (CC BY-SA 4.0), which cites: Getz, "Biomass transformation webs provide a unified approach to consumer-resource modelling", Ecology Letters, 2011, p. 113–124 (original not read by us) en.wikipedia.org
- "Overview of Parasitology", Australian Society of Parasitology and Australian Research Council/National Health and Medical Research Council) Research Network for Parasitology, July 2010. facts only, no text reused. parasite.org.au
- Wikipedia, "Parasitism" (CC BY-SA 4.0), which cites: "The Making of Alien's Chestburster Scene", The Guardian, 13 October 2009 (we also read that source) en.wikipedia.org
- Wikipedia, "Parasitism" (CC BY-SA 4.0), which cites: σῖτος , Liddell, Henry George; Scott, Robert, A Greek–English Lexicon, on Perseus Digital Library; σιτισμός , Liddell, Henry George; Scott, Robert, A Greek–English Lexicon, on Perseus Digital Library (original not read by us) en.wikipedia.org
- Wikipedia, "Parasitism" (CC BY-SA 4.0), which cites: "A Classification of Animal-Parasitic Nematodes", plpnemweb.ucdavis.edu; Garcia, "Classification of Human Parasites, Vectors, and Similar Organisms", Clinical Infectious Diseases, 1999, p. 734–746; "Overview of Parasitology", Australian Society of Parasitology and Australian Research Council/National Health and Medical Research Council) Research Network for Parasitology, July 2010; Vecchione, "The mesoparasitic copepod Pennella balaenopterae and its significance as a visible indicator of health status in dolphins (Delphinidae): a review", Jo en.wikipedia.org
- "Helminth Parasites", Australian Society of Parasitology. facts only, no text reused. parasite.org.au
Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Parasitism (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.
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