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Encyclopedia > Agnatha
Idealized agnatha.

Agnatha (Greek, "no jaws") is a paraphyletic[citation needed] superclass of jawless fish in the phylum CHI YOU ARE THE BESThordata, subphylum Vertebrata. Agnatha have existed since the Cambrian, and continue to live in modern times. There are two extant groups of jawless fish (sometimes called cyclostomes), the lampreys and the hagfish, with about 100 species between them. In addition to the absence of jaws, Agnatha are characterised by absence of paired fims; the presence of a notochord both in larvae and adults; and seven or more paired gill pouches. The bronchial arches supporting the gill pouches lie close to the body surface. There is a light sensitive pineal eye (homologous to the pineal gland in mammals). There is no identifiable stomach. Fertilization is external. The Agnatha are ectothermic, with a cartilaginous skeleton, and the heart contains 2 chambers. Image File history File links Download high resolution version (1021x326, 12 KB)i draw it with macromedia flash mateus zica Mateus Zica 04:54, 27 October 2005 (UTC) dbenbenn | talk 22:49, 8 October 2005 (UTC) File history Legend: (cur) = this is the current file, (del) = delete this old version... Image File history File links Download high resolution version (1021x326, 12 KB)i draw it with macromedia flash mateus zica Mateus Zica 04:54, 27 October 2005 (UTC) dbenbenn | talk 22:49, 8 October 2005 (UTC) File history Legend: (cur) = this is the current file, (del) = delete this old version... Paraphyletic - Wikipedia /**/ @import /skins-1. ... Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. ... Phylum (plural: phyla) is a taxon used in the classification of animals, adopted from the Greek phylai the clan-based voting groups in Greek city-states. ... Typical classes Petromyzontidae (lampreys) Placodermi - extinct Chondrichthyes (cartilaginous fish) Acanthodii - extinct Actinopterygii (ray-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ... The Cambrian is a major division of the geologic timescale that begins about 542 ± 1. ... Subfamilies Geotriinae Mordaciinae Petromyzontinae A lamprey (sometimes also called lamprey eel) is a jawless fish with a toothed, funnel-like sucking mouth. ... Genera Eptatretus Myxine Nemamyxine Neomyxine Notomyxine Paramyxine Quadratus This article is about the Hagfish. ... The hierarchy of scientific classification. ... The notochord is a flexible, rod-shaped body found in embryos of all chordates. ... For other uses, see Gill (disambiguation). ... The pineal gland (also called the pineal body or epiphysis) is a small endocrine gland in the brain. ... The pineal gland (also called the pineal body or epiphysis) is a small endocrine gland in the brain. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the production of milk in female mammary glands and by the presence of: hair, three middle ear bones used in hearing, and a neocortex region in... In anatomy, the stomach is a bean-shaped hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication. ... Cold-blooded organisms, more technically known as poikilothermic, are animals that have no internal metabolic mechanism for regulating their body temperatures. ... Cartilage is a type of dense connective tissue. ... This article does not cite any references or sources. ... The heart and lungs, from an older edition of Grays Anatomy. ...


jawless fish come from te ocean and they eat worms and dead fish


Although they are superficially similar, many of these similarities are probably shared primitive characteristics of ancient vertebrates, and modern classifications tend to move the hagfish into a separate group (the Myxini or Hyperotreti), with the lampreys (Hyperoartii) being more closely related to the jawed fishes. Subfamilies Geotriinae Mordaciinae Petromyzontinae A lamprey is a type of fish with a toothed, funnel-like, jawless sucking mouth, with which most species bore into the flesh of other fishes to suck their blood. ...


Fossil agnathans

Haikouichthys is a fossil agnathan.
Cephalaspis is another fossil agnathan.

Although a minor element of modern marine fauna, Agnatha were prominent among the early fish in the early Paleozoic. Two types of Early Cambrian animal apparently having fins, vertebrate musculature, and gills are known from the early Cambrian Maotianshan shales of China: Haikouichthys and Myllokunmingia. They have been tentatively assigned to Agnatha by Janvier. A third possible agnathid from the same region is Haikouella. A possible agnathid that has not been formally described was reported by Simonetti from the Middle Cambrian Burgess Shale of British Columbia. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... It was a fish who lived in the Silurian period it had an armoured and an advanced brain never been seen in Earths history so far. ... Fauna is a collective term for animal life. ... The Paleozoic Era (from the Greek palaio, old and zoion, animals, meaning ancient life) is the earliest of three geologic eras of the Phanerozoic eon. ... The Cambrian is a major division of the geologic timescale that begins about 542 ± 1. ... This article does not cite any references or sources. ... The Cambrian is a major division of the geologic timescale that begins about 542 ± 1. ... The Maotianshan shale is a lower Cambrian (Atdabanian) rock formation, of ca 522 Mya, now lying exposed in the Yunnan Province of China in the villages of Ercaicun and Chengjiang near the city of Kunming. ... The Haikouichthys is a primitive fish-like animal from the Lower Cambrian Maotianshan shales of China. ... The Myllokummingia is a primitive, probably agnathid (jawless) fish from the Lower Cambrian Maotianshan shales of China thought to be a vertebrate (see external links). ... The Haikouella is a probable chordate from the Lower Cambrian beds of Xiangchiang in Yunnan, China. ... Hallucigenia sparsa, one of the organisms unique to the Burgess Shale. ... Motto: Splendor Sine Occasu (Latin: Splendour without diminishment) Capital Victoria Largest city Vancouver Official languages English Government - Lieutenant-Governor Iona Campagnolo - Premier Gordon Campbell (BC Liberal) Federal representation in Canadian Parliament - House seats 36 - Senate seats 6 Confederation July 20, 1871 (6th province) Area  Ranked 4th - Total 944,735 km...


Many Ordovician, Silurian, and Devonian agnathans were armored with heavy bony-spiky plates. The first armored agnathans—the Ostracoderms, precursors to the bony fish and hence to the tetrapods (including human beings)—are known from the middle Ordovician, and by the Late Silurian the agnathans had reached the high point of their evolution. Agnathans declined in the Devonian and never recovered. This article or section does not cite its references or sources. ... Subclasses Actinopterygii Sarcopterygii Osteichthyes are the bony fish, a group paraphyletic to the land vertebrates, which are sometimes included. ... Classes Synapsida Sauropsida Amphibia A tetrapod (Greek tetrapoda, four-legged) is a vertebrate animal having four feet, legs or leglike appendages. ... Human beings are defined variously in biological, spiritual, and cultural terms, or in combinations thereof. ... Artist impression of the Ordovician Sea. ... The Silurian is a major division of the geologic timescale that extends from the end of the Ordovician period, about 443. ... Artists illustration of a Devonian scene. ...


Groups

Myxini (hagfish)
Hyperoartia
Genera Eptatretus Myxine Nemamyxine Neomyxine Notomyxine A hagfish is any of several marine chordates of the class Myxini, also known as Hyperotreti. ... Genera Eptatretus Myxine Nemamyxine Neomyxine Notomyxine Paramyxine Quadratus This article is about the Hagfish. ... Subfamilies Geotriinae Mordaciinae Petromyzontinae A lamprey is a jawless fish with a toothed, funnel-like sucking mouth, with which most species bore into the flesh of other fishes to suck their blood. ...

Pteraspidomorphi
Thelodonti
Anaspida
Cephalaspidomorphi
Subfamilies Geotriinae Mordaciinae Petromyzontinae A lamprey is a type of fish with a toothed, funnel-like, jawless sucking mouth, with which most species bore into the flesh of other fishes to suck their blood. ... Subfamilies Geotriinae Mordaciinae Petromyzontinae A lamprey (sometimes also called lamprey eel) is a jawless fish with a toothed, funnel-like sucking mouth. ... Orders Arandaspida Heterostraci Thelodontidae Eriptychiida Astraspida Pteraspidomorphi is an extinct subclass of early jawless fish. ... Thelodonti is an alternative name for the taxon Coelolepida. ... Anaspida are a extinct marine subgroup of the agnatha. ... subgroups Osteostraci Galeaspida Pituriaspida Anaspida Hyperoartia (lampreys) Cephalaspidomorphs are a taxon of jawless fishes named for the cephalaspids, which is another name for the osteostracans. ...


  Results from FactBites:
 
Florida Museum of Natural History Ichthyology Department (792 words)
The second class is the Actinopterygii and contains fish such as gars, sturgeons, bowfins, and the very large group of fishes known as the telelosts.
The bony fish differ from the Agnatha because they have jaws.
The bony fish differ from the Chondrichthyes because the bony fish have skeletons made of bone.
Agnatha Summary (819 words)
Agnatha (Greek, "no jaws") is a paraphyletic superclass of jawless fish in the phylum Chordata, subphylum Vertebrata.
In addition to the absence of jaws, Agnatha are characterised by absence of paired fins; the presence of a notochord both in larvae and adults; and seven or more paired gill pouches.
Although a minor element of modern marine fauna, Agnatha were prominent among the early fish in the early Paleozoic.
  More results at FactBites »

 
 

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