Also found in: Thesaurus, Medical, Encyclopedia.
Related to agnathan: Osteichthyes


Any of various fishes lacking jaws, including the hagfishes and the lampreys and many extinct groups, such as the ostracoderms.

[a- + Greek gnathos, jaw; see genu- in Indo-European roots + -an.]

ag′na·than adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Animals) any jawless eel-like aquatic vertebrate of the superclass Agnatha, which includes the lampreys and hagfishes
(Zoology) of, relating to, or belonging to the superclass Agnatha. See also cyclostome
[C19: from New Latin agnatha, from a-1 + Greek gnathos jaw]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.agnathan - eel-shaped vertebrate without jaws or paired appendages including the cyclostomes and some extinct formsagnathan - eel-shaped vertebrate without jaws or paired appendages including the cyclostomes and some extinct forms
aquatic vertebrate - animal living wholly or chiefly in or on water
Agnatha, superclass Agnatha - superclass of eel-shaped chordates lacking jaws and pelvic fins: lampreys; hagfishes; some extinct forms
ostracoderm - extinct fish-like jawless vertebrate having a heavily armored body; of the Paleozoic
heterostracan - extinct jawless fish with the anterior part of the body covered with bony plates; of the Silurian and Devonian
cephalaspid, osteostracan - extinct jawless fish of the Devonian with armored head
anaspid - extinct small freshwater jawless fish usually having a heterocercal tail and an armored head; of the Silurian and Devonian
conodont - small (2 inches long) extinct eellike fish with a finned tail and a notochord and having cone-shaped teeth containing cellular bone; late Cambrian to late Triassic; possible predecessor of the cyclostomes
cyclostome - primitive aquatic vertebrate
lamper eel, lamprey, lamprey eel - primitive eellike freshwater or anadromous cyclostome having round sucking mouth with a rasping tongue
hagfish, slime eels - eellike cyclostome having a tongue with horny teeth in a round mouth surrounded by eight tentacles; feeds on dead or trapped fishes by boring into their bodies
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in periodicals archive ?
Luksevics in the Department of Geology, Faculty of Geography and Earth Sciences, University of Latvia), 1.42.738.2017 and 3.42.1103.2016 (collecting the agnathan and fish remains from the Gauja and Amata deposits of the Baltic Region and comparison of vertebrate assemblages).
The first assemblage of vertebrates to be described from the Eastport Formation of Maine, USA, includes agnathan remains comprising scale fragments of osteostracans and anaspids, and scales of thelodonts.
The two main taxonomic groups of agnathan or cyclostome fish are Hyperoartia, lampreys and Hyperotreti, and hagfish (for a review of agnathan ion and water homeostasis see Karnaky, 1998; Evans and Claiborne, 2009).
Aryl hydrocarbon receptor function in early vertebrates: inducibility of cytochrome P450 1A in agnathan and elasmobranch fish.
We collected a total of 18,852 nekton individuals: two cephalopud, one agnathan, two elasmobranch, and 57 fish taxa from 163 surface trawls (see Table 1 for scientific names of all species).
The two structures of primary importance in the transition from agnathan (jawless) fish to gnathostomes were the mandibular arch (gill arch 2) and the hyoid arch (gill arch 3).
The Boothiaspidinae, a new agnathan subfamily (Heterostraci, Cyathaspididae) from the Late Silurian and Early Devonian of the western United States and the Canadian Arctic.
Somatic diversification of variable lymphocyte receptors in the agnathan sea lamprey.
Metamorphosis of larval sea lamprey Petromyzon marinus (an agnathan fish) is also affected by exposure to perchlorate (Manzon and Youson 1997, 2002; Manzon et al.
This agnathan system is in many ways analogous in function to jawed vertebrate Ig systems.