Mostly Fish

Hagfish
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Hagfish are marine craniates of the class Myxini, also known as Hyperotreti. Myxini is the only class in the clade Craniata that does not also belong to the subphylum Vertebrata. Despite their name, there is some debate about whether they are strictly fish (as there is for lampreys), since they belong to a much more primitive lineage than any other group that is commonly defined fish (Chondrichthyes and Osteichthyes). Their unusual feeding habits and slime-producing capabilities have led members of the scientific and popular media to dub the hagfish as the most "disgusting" of all sea creatures.

Chondrichthyes
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myxine

noun
type genus of the Myxinidae (typical hagfishes)

WordNet® 3.0, © 2006 by Princeton University.
Webster's Revised Unabridged Dictionary - Cite This Source - Share This
Myxine

\Myx"ine\, n. (Zo["o]l.) A genus of marsipobranchs, including the hagfish. See Hag, 4.

Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.


The Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nostrils, scales, two-chambered hearts, and skeletons made of cartilage rather than bone. They are divided into two subclasses: Elasmobranchii (sharks, rays and skates) and Holocephali (chimaera, sometimes called ghost sharks).

Osteichthyes are a taxonomic superclass of fish, also called bony fish that includes the ray-finned fish (Actinopterygii) and lobe finned fish (Sarcopterygii). The split between these two classes occurred around 440 mya.

In most classification systems the Osteichthyes are paraphyletic with land vertebrates. That means that the nearest common ancenstor of all Osteichthyes includes tetrapods amongst its descendants. Actinopterygii (ray-finned fish) are monophyletic, but the inclusion of Sarcopterygii in Osteichthyes causes Osteichthyes to be paraphyletic.

Most bony-fish belong to the Actinopterygii; there are only eight living species of lobe finned fish (Sarcopterygii) including the lungfish and coelacanths.(Some species of lobe-finned fish have jointed bones.)

They are traditionally treated as a class of vertebrates, with subclasses Actinopterygii and Sarcopterygii, but some newer schemes divide them into several separate classes.

The vast majority of fish are osteichthyes, and most of these are fit for human consumption. Osteichthyes are the most various group of vertebrates, consisting of over 29,000 species, making them the largest class of vertebrates in existence today.

Teleostomi
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Teleostomi is a clade of jawed vertebrates that includes the tetrapods, bony fish, and the wholly extinct acanthodian fish. Key characters of this group include an operculum and a single pair of respiratory openings, features which were lost or modified in some later representatives. The teleostomes include all jawed vertebrates except the chondrichthyans and the placoderms.

The clade Teleostomi should not be confused with the similar-sounding fish clade Teleostei.

Taxonomy and phylogeny
Subphylum Vertebrata
+-(unranked) Gnathostomatomorpha
+-Infraphylum Gnathostomata
+-Class Placodermi
- extinct (armored gnathostomes)
+Microphylum Eugnathostomata (true jawed vertebrates)
+-Class Chondrichthyes (cartilaginous fish)
+-(unranked) Teleostomi (Acanthodii & Osteichthyes)
+-Class Acanthodii - extinct ("spiny sharks")
+Superclass Osteichthyes (bony fish)
+ +-Class Actinopterygii (ray-finned fish)
+ +-Class Sarcopterygii (lobe-finned fish)
+Superclass Tetrapoda
+-Class Amphibia (amphibians)
+(unranked) Amniota (amniotic egg)
+-Class Sauropsida (reptiles or sauropsids)
+-Class Aves (birds)
+-Class Synapsida
+-Class Mammalia (mammals) Note: lines show evolutionary relationships.

Teleostei is one of three infraclasses in class Actinopterygii, the ray-finned fishes. This diverse group, which arose in the Triassic period , includes 20,000 extant species in about 40 orders. The other two infraclasses, Holostei and Chondrostei, are paraphyletic.


DICTIONARY
Hyperotreti

Hyperotreta \Hy`per*o*tre"ta\, n. pl. [NL., fr. Gr. ? the plate + ? perforated.] (Zo["o]l.) An order of marsipobranchs, including the Myxine or hagfish and the genus Bdellostoma. They have barbels around the mouth, one tooth on the plate, and a communication between the nasal aperture and the throat. See Hagfish. [Written also Hyperotreti.]

Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.

gnathostomata

noun
comprising all vertebrates with upper and lower jaws

WordNet® 3.0, © 2006 by Princeton University.
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Gnathostomata

Gnathostoma \Gna*thos"to*ma\, n. pl. [NL., from Gr. ? the jaw + ?, ?, the mouth.] (Zo["o]l.) A comprehensive division of vertebrates, including all that have distinct jaws, in contrast with the leptocardians and marsipobranchs (Cyclostoma), which lack them. [Written also Gnathostomata.]

Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.


Teleostomi

\Te"le*os`to*mi\, n. pl. [NL., fr. Gr. ? complete + ? mouth.] (Zo["o]l.) An extensive division of fishes including the ordinary fishes (Teleostei) and the ganoids.

Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.


Os·te·ich·thy·es /??sti'?k?i?iz/ Pronunciation Key - Show Spelled Pronunciation[os-tee-ik-thee-eez] Pronunciation Key - Show IPA Pronunciation
–noun the class comprising the bony fishes.


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[Origin: < NL < Gk osté(on) bone (see oste-) + ichthýes fish (pl. of ichthy¯´s)]
Dictionary.com Unabridged (v 1.1)
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006.
WordNet - Cite This Source - Share This osteichthyes

noun
a class of fish having a skeleton composed of bone in addition to cartilage

WordNet® 3.0, © 2006 by Princeton University.

chondrichthyes

noun
cartilaginous fishes

WordNet® 3.0, © 2006 by Princeton University.
Merriam-Webster's Medical Dictionary - Cite This Source - Share This
Main Entry: Chon·drich·thy·es
Pronunciation: kän-'drik-thE-"Ez
Function: noun plural
: a class comprising cartilaginous fishes with well-developed jaws and including the sharks, skates, rays, chimeras, and extinct related forms —compare CYCLOSTOMATA

Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.

cyclostomata

noun
primitive jawless aquatic vertebrate: lampreys; hagfishes

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Main Entry: Cy·clo·sto·ma·ta
Pronunciation: "sI-klO-'stO-m&t-&, "sik-lO-, -'stäm-&t-&
Function: noun plural
: a class or other taxon of primitive vertebrates that have a large jawless sucking mouth, no limbs or paired fins, a wholly cartilaginous skeleton with persistent notochord, and 6 to 14 pairs of gill pouches and that include the lampreys and the hagfishes —compare CHONDRICHTHYES

Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
Webster's Revised Unabridged Dictionary - Cite This Source - Share This
Cyclostomata

\Cy`clo*stom"a*ta\ (s?`kl?-st?m"?-t?), Cyclostoma\Cy*clos"to*ma\ (s?-kl?s"t?-m?), n. pl. [NL., fr. Gr. ky`klos circle + sto`ma, -atos mouth.] (Zo["o]l.) A division of Bryozoa, in which the cells have circular apertures.

Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.

sarcopterygian (sär-kop't?-rij'e-?n) Pronunciation Key
See lobe-finned fish.

ac·ti·nop·te·ryg·i·an /?ækt??n?pt?'r?d?i?n/ Pronunciation Key - Show Spelled Pronunciation[ak-tuh-nop-tuh-rij-ee-uhn] Pronunciation Key - Show IPA Pronunciation
–adjective 1. belonging or pertaining to the Actinopterygii, a group of bony fishes.
–noun 2. an actinopterygian fish.


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[Origin: < NL Actinopterygi(i) (pl.) (actino- actino- + Gk pterýgi(on) fin, equiv. to pteryg- (s. of ptéryx wing) + -ion dim. suffix) + -an]
Dictionary.com Unabridged (v 1.1)
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006.

Marsipobranch

\Mar"si*po*branch`\, n. (Zo["o]l.) One of the Marsipobranchia.

Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.

Marsipobranchia

\Mar"si*po*bran"chi*a\, n. pl. [NL., fr. Gr. ? a pouch + ? a gill.] (Zo["o]l.) A class of Vertebrata, lower than fishes, characterized by their purselike gill cavities, cartilaginous skeletons, absence of limbs, and a suckerlike mouth destitute of jaws. It includes the lampreys and hagfishes. See Cyclostoma, and Lamprey. Called also Marsipobranchiata, and Marsipobranchii.

Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.

elasmobranchii

noun
sharks; rays; dogfishes; skates

WordNet® 3.0, © 2006 by Princeton University.
Merriam-Webster's Medical Dictionary - Cite This Source - Share This
Main Entry: Elas·mo·bran·chii
Pronunciation: i-"laz-m&-'bra[ng]-kE-"I
Function: noun plural
synonym of CHONDRICHTHYES

holocephali

noun
chimaeras and extinct forms

WordNet® 3.0, © 2006 by Princeton University.
Webster's Revised Unabridged Dictionary - Cite This Source - Share This
Holocephali

\Hol`o*ceph"a*li\, n. pl. [NL., from Gr. "o`los whole + ? head.] (Zo["o]l.) An order of elasmobranch fishes, including, among living species, only the chim[ae]ras; -- called also Holocephala. See Chim[ae]ra; also Illustration in Appendix.

Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.