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A class of vertebrates comprising the cartilaginous, jawed fishes. The Chondrichthyes have traditionally included the subclasses Elasmobranchii (sharks, skates, and rays) and Holocephali (ratfishes). A classification scheme for the Chondrichthyes follows.

  • Class Chondrichthyes
  • Subclass Elasmobranchii
  • Order: Cladoselachii
  • Pleurocanthodii
  • Selachii
  • Batoidea
  • Subclass Holocephali
  • Order Chimaeriformes

A group of Devonian armored fishes, the Placodermi, has usually been regarded as ancestral to the Chondrichthyes, but this derivation is not certain. Another group of primitive jawed fishes called acanthodians, which are considered by many as ancestral to the higher bony fishes, exhibit certain primitive elasmobranch-like features. In any case it is probable that the elasmobranchs and ratfishes arose independently of each other sometime during the Silurian or Early Devonian. See Acanthodii, Placodermi

The most distinctive feature shared by the elasmobranchs and ratfishes is the absence of true bone. In both groups the endoskeleton is cartilaginous; in some cases it may be extensively calcified. Because even calcified cartilage is rarely preserved, the fossil record of the Chondrichthyes is represented mainly by teeth and spines, with only occasional associated skeletons.

Other characteristics of the Chondrichthyes include placoid scales, clasper organs on the pelvic fins of males for internal fertilization, a urea-retention mechanism, and the absence of an air (swim) bladder. Both groups have primarily always been marine predators, although they have repeatedly invaded fresh water throughout their long history. The elasmobranchs have probably always fed as they do today, on other fishes as well as on soft and hard-bodied invertebrates. The ratfishes have most likely concentrated on invertebrates, although modern forms occasionally also feed on smaller fishes. See Ray, Swim bladder

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a class of fishes that includes two subclasses: Elasmobranchii and Holocephali. The fish have a cartilaginous skeleton fortified by calcification. The scales are placoid. There is a spiral valve in the intestine and an arterial cone in the heart. Many Chondrichthyes have a cloaca. In Elasmobranchii the skull is hyostylic (with a single articulation of the jaw with the skull) or amphistylic (with two such articulations). In Holocephali the skull is autostylic (with the jaw concresced with the skull). In almost all Chondrichthyes insemination is apparently internal. Males have a special copulatory organ, the pterygopodium, which is formed from rays of the ventral fins.

The Chondrichthyes are viviparous or oviparous. The majority are predators. They are predominantly marine fish; only a few Elasmobranchii have adapted to freshwater life. Fossil Chondrichthyes are known from the Devonian.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


(vertebrate zoology)
A class of vertebrates comprising the cartilaginous, jawed fishes characterized by the absence of true bone.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
acuta represents a clearly different model from some studied cartilaginous fishes (Jezior and Hamlett, 1995; Hamlett et al., 1999) and is similar to those present in R.
Yolk production in cartilaginous fishes occurs by endogenous or exogenous mechanisms, or a combination of both (Prisco et al., 2002b).
Cartilaginous fishes (Chondrichthyes) exhibit a variety of sexual dimorphisms.
Careful measurement of the heads of other shark species may reveal that rostral cartilage elongation at sexual maturity, with concomitant changes in head shape, is a widespread phenomenon among cartilaginous fishes.
However, the neurons subservient to horizontal eye movements in cartilaginous fishes (sharks, skates, and rays) are asserted, by some, to be organized quite differently from those of other vertebrates (7-9).