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hagfish,primitive, jawless marine fish of the family Myxinidae, of worldwide distribution in cold and temperate waters. Its rudimentary skeleton, of cartilage rather than bone, has a braincase, but no jaw. The circular sucking mouth has rows of horny teeth. There is a single median nostril and the eyes are poorly developed. Like the other jawless fishes, the lampreyslamprey,
name for several primitive marine and freshwater jawless fishes of the order Petromyzontiformes. As in the other jawless fish, the hagfish, the adult lamprey retains the notochord, the supporting structure that in higher vertebrates is found only in the embryo.
..... Click the link for more information. , hagfish retain the notochordnotochord
, in biology, supporting rod running most of the length of animals of the phylum Chordata and present at varying times in the life cycle. Composed of large cells packed within a firm connective tissue sheath, the notochord lies between the neural tube (spinal cord) and
..... Click the link for more information. , a supporting structure found in higher vertebrates only in the embryo, throughout life. They lack a sympathetic nervous system, a spleen, and scales. Hagfish, or hags, spend much time embedded in muddy bottoms. They are chiefly scavengers, but also parasitize slow-moving fishes, eating their way into the victim's body and leaving only the skin and skeleton. Also known as slime eels, hagfish have glands on either side of their bodies that produce enormous quantities of mucoid material, probably as a defense mechanism. The sexes are separate, although an individual may have rudimentary organs of the opposite sex. Spawning occurs throughout the year; no larval stage is known. The Atlantic hagfish, Myxine glutinosa, may reach a length of 30 in. (76 cm). The Pacific hagfish, Eptatretus stouti, has been extensively used in physiological studies. The hagfish is classified in the phylum ChordataChordata
, phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal skeletal support at some stage of their development. Most chordates are vertebrates (animals with backbones), but the phylum also includes some small marine invertebrate animals.
..... Click the link for more information. , subphylum Vertebrata, class Myxini, order Myxiniformes, family Myxinidae.
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The common name for the jawless fishes composing the order Myxinoidea.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.