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Cyclostome

Cyclostome is a biological term used in a few different senses:for the taxon Cyclostomi, which comprises the extant jawless fishes: the hagfish (Myxini) and the lampreys (Petromyzontidae). This was thought for a time to be a paraphyletic group and this usage of the term was deprecated by some. However, there is strong molecular evidence for cyclostome monophyly, and thus the term remains in use. for the Order Cyclostomatida of bryozoans, tiny animals that live in colonies and form large calcitic skeletons. for one of two subgroups of braconid wasps.

Last revised
Jun 22, 2026
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Cyclostome is a biological term (from the Greek for "round mouth") used in a few different senses:

  • for the taxon Cyclostomi, which comprises the extant jawless fishes: the hagfish (Myxini) and the lampreys (Petromyzontidae). This was thought for a time to be a paraphyletic group and this usage of the term was deprecated by some. However, there is strong molecular evidence for cyclostome monophyly,1 and thus the term remains in use.
  • for the Order Cyclostomatida of bryozoans, tiny animals that live in colonies and form large calcitic skeletons.
  • for one of two subgroups of braconid wasps.
References

References

  1. Stock, David; Whitt GS (7 August 1992). "Evidence from 18S ribosomal RNA sequences that lampreys and hagfishes form a natural group". Science. 257 (5071): 787–9. Bibcode:1992Sci...257..787S. doi:10.1126/science.1496398. PMID 1496398.