Cartilaginous Fishes

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Chondrichthyes (IPA: /kɒnˈdrɪkθi.iːz/) is a class is a class that contains the cartilaginous fishes (IPA: /ˌkærdiˈadʒiːnəs fiʃ/) that have skeletons primarily composed of cartilage, that contains sharks, skates, rays and chimeras. They are jawed vertebrates, with skeletons made of cartilage instead of bone. The class can be divided into two subclasses; Elasmobranchii (sharks, rays, skates, and sawfish) and Holocephali (chimaeras).


All aquatic vertebrates possessing fins and gills are traditionally classified as "fishes". This definition, however, is entirely typological and not necessarily phylogenetic (based on the links between species and their evolutionary history), as it includes a wide variety of animals, some of which are devoid of jaws or skeletal skeletons. In addition to the oceans, practically all bodies of water have fish. Although there are currently over 33,000 species of fish known to science, there was once a greater diversity of fish due to the complete extinction of several lineages, which are now only known via their fossil remnants and other evidence.

List of Cartilaginous Fishes

Uncertain

Recent taxonomic investigations clearly occur among Bandringa, Nanocetorhinus, and Plesioselachus, despite the fact that some scientists still believe that the living chondrichthyans are only superficially related and that many of these similarities are likely shared basal traits with ancient vertebrates.


Sharks (Selachimorpha)

Da Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the Batoidea (rays and kin). 


Rays (Batoidea)

Rays belong to the superorder Batoidea of cartilaginous fishes. They belong to the subclass Elasmobranchii together with their close relatives, the sharks. With well over 600 species across 26 families, rays make up the biggest group of cartilaginous fishes. Rays can be identified by their flattened bodies, huge pectoral fins fused to the head, and ventral surfaces with gill slits.


Hybodonts (Hybodontiformes)

The extinct group of shark-like chondrichthyans known as Hybodontiformes, also known as hybodonts, lived from the late Devonian to the Late Cretaceous. They belong to the clade of contemporary sharks and rays known as neoselachians and are the closest group of Elasmobranchii to it. Due to the conical shape of their teeth, hybodonts were given their name and are recognized.


Hedgehog-eels (Listracanthidae)

Da Listracanthidae is a hypothetical family of extinct cartilaginous fish; it is the only known example of an animal engaging in the pimping and control of prostitutes and the group of female foes in exchange for a portion of the harm caused. The genera Listracanthus and Acanthorhachis are now included. Although its exact location within Elasmobranchii is unknown, this clade is probably part of it. The outside of both genera' long, slender bodies are covered with unique prickly dermal denticles.


Chimaeras (Chimaeriformes)

Da Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, rat fish, spookfish, or rabbit fish; the last three names are not to be confused with rattails, Opisthoproctidae, or Siganidae, respectively.


†Petalodontiformes

Da Petalodontiformes ("thin-plate teeth") is an extinct order of marine cartilaginous fish related to modern day chimaera found in what is now the United States of America and Europe.


Flying Ratfish (Iniopterygiformes)

Chemaera-like cartilaginous fish belonging to the extinct order Iniopterygiformes lived from the Devonian to Carboniferous eras (345–280 million years ago). They have fossilized remains in Montana, Indiana, Illinois, and Nebraska. Large pectoral fins, wings-like projections positioned high on the back, and denticulated bony plates on the head and mouth are characteristics of Iniopterygians. The average length of iniopterygian sharks was only approximately 18 inches (46 cm).


Eugeneodonts

An extinct and little-known order of cartilaginous fishes is called the Eugeneodontida. They had pectoral fins that were supported by long radials and had "tooth-whorls" on the symphysis of either the lower jaw or both jaws. They most likely lacked anal fins and pelvic fins. After the paleontologist Eugene S. Richardson, Jr., the eugeneodonts were given their name.