cni·​dar·​i·​an | \ nī-ˈder-ē-ən How to pronounce cnidarian (audio) \

Definition of cnidarian

: any of a phylum (Cnidaria) of radially symmetrical, aquatic, invertebrate animals that have a hollow digestive cavity opening to the outside by a single opening surrounded by one or more nematocyst-studded whorls of tentacles, that occur as single or colonial sessile, typically columnar polyps or usually free-swimming, bell-shaped medusae, and that include the corals, sea anemones, jellyfishes, hydras, and Portuguese man-of-wars Welcome to the world of cnidarians—a family of sea anemones, jellyfish and other marine invertebrates that kill their enemies and prey by firing poisonous, microscopic projectiles called nematocysts.— R. Weiss

called also coelenterate

Other Words from cnidarian

cnidarian adjective

Examples of cnidarian in a Sentence

Recent Examples on the Web If these typical cnidarians strike you as a bit bizarre, the myxozoans are even further out past the borders of the familiar. John Timmer, Ars Technica, 26 Feb. 2020 In 1995, however, Mark Siddall, then at the Virginia Institute of Marine Science, and his colleagues argued that myxosporeans are weird members of the cnidarians, the group that includes jellyfish and corals. Quanta Magazine, 19 Aug. 2019 The fork leading to cnidarians represents the final turnoff before animals become bilaterally symmetric, which makes them an interesting group to study because of the greater complexity that came with that later innovation. Quanta Magazine, 8 Jan. 2019 To find out, the researchers decided to sequence the genome of Aurelia, the moon jellyfish, and then compare it to those of cnidarians without medusas. Quanta Magazine, 8 Jan. 2019 That is in contradistinction to Cambrian fossils, among which are found representatives of all the main animal groups (annelids, arthropods, brachiopods, chordates, cnidarians, echinoderms, molluscs and so on) that are around today. The Economist, 7 June 2018 The first saw the emergence of brachiopods and molluscs, the second that of annelids, cnidarians, echinoderms and chordates (a group that includes the vertebrates). The Economist, 7 June 2018 Researchers initially thought these nematocysts might be genetically similar to those of cnidarians, animals such as jellyfish and sea anemones. Rachel Brown, National Geographic, 5 Apr. 2017 In fact, the plankton’s ballistic mechanisms are actually much more complex than those of cnidarians. Rachel Brown, National Geographic, 5 Apr. 2017 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'cnidarian.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of cnidarian

1894, in the meaning defined above

History and Etymology for cnidarian

New Latin Cnidaria, phylum name (from Greek knī́dē "nettle, sea nettle"—of uncertain origin— + Latin -āria, neuter plural of -ārius -ary entry 2) + -an entry 1

Note: The taxon Cnidaria is based ultimately on French cnidaire, a vernacular designation for a sub-class used by H. Milne Edwards in Histoire naturelle des coralliaires ou polypes proprements dits, tome 1 (Paris, 1857), p. 95. Milne Edwards alludes to use of Greek knī́dē for a sea nettle by Aristotle in Historia animalium, Book 5. The Greek noun has been associated with the verb knízein "to scratch, chop up, provoke" (perhaps from an Indo-European base *knid-), but the vowel length in knī́dē has no good explanation.

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The first known use of cnidarian was in 1894

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Cite this Entry

“Cnidarian.” Dictionary, Merriam-Webster, Accessed 8 Aug. 2022.

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cni·​dar·​i·​an | \ -ē-ən How to pronounce cnidarian (audio) \

Medical Definition of cnidarian

Other Words from cnidarian

cnidarian adjective

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