Entozoa

{{Short description|Historical taxon}}

Entozoa is an obsolete taxonomic term that historically referred to a group of parasitic animals that live inside the bodies of other organisms.{{cite book |url=https://zmmu.msu.ru/files/Библиотека%20Павлинова/macleay-1819_horae%20entomologic-1-12.pdf |title=Horae entomologicae : or, Essays on the annulose animals |last1=Macleay |first1=William Sharp |year=1819}} It was originally used in older classifications to describe a diverse assortment of internal parasites, including parasitic worms (like tapeworms and roundworms) and some protozoans.{{cite book |last1=Cobbold |first1=Thomas Spencer |title=Entozoa: an introduction of the study of helminthology, with reference to the internal parasites of man |year=1869 |url=https://books.google.com/books?id=YiVEAQAAMAAJ}} However, the term Entozoa is only broadly descriptive and not based on evolutionary relationships, making it a convenient but scientifically invalid grouping. Coined by Swedish-German naturalist Karl Rudolfi in 1808,{{cite journal |title=History of Ecological Sciences, Part 46: From Parasitology to Germ Theory |first1=Frank N. |last1=Egerton |year=2013 |journal=The Bulletin of the Ecological Society of America |volume=94 |issue=2 |pages=136–164 |doi=10.1890/0012-9623-94.2.136|bibcode=2013BuESA..94..136E }} the term is considered obsolete and no longer used in modern taxonomy.

Advances in taxonomy and phylogenetics have replaced such groupings with more precise classifications based on evolutionary relationships.{{cite book |url=https://extensionentomology.tamu.edu/wp-content/uploads/sites/6/2021/03/The-Torre-Bueno-Glossary-of-Entomology.pdf|first1=J. R. de la |last1=Torre-Bueno |date=1989 |publisher=New York Entomological Society |title=The Torre-Bueno Glossary of Entomology |isbn=0-913424-13-7}} Today, these organisms are classified within different kingdoms or phyla, such as Protozoa (single-celled organisms, like Plasmodium, a cause of malaria); Nematoda (roundworms, including the genus Ascaris); and Platyhelminthes (flatworms, like tapeworms and flukes).{{cite journal |title= On the Entozoa, Especially Those Infesting the Human Subject: Bring the Substance of a Lecture Given at Queen's College |first1=Robert C. R. |last1=Jordan |journal=Association Medical Journal |volume=3 |issue=139 |year=1855 |pages=809–812 |jstor=25496610}}

The term Entozoa was initially used at a broad taxonomic level, closer to the rank of a kingdom or a similarly overarching group in older biological classifications. It functioned as a general, non-systematic category for all internal parasites, reflecting the limited understanding of evolutionary relationships in the early 19th century.