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Vertebrate

Vertebrate


Conodonta
Hyperoartia
:Petromyzontidae (lampreys)
Pteraspidomorphi (early jawless fish)
Thelodonti
Anaspida
Cephalaspidomorphi (early jawless fish)
:Galeaspida
:Pituriaspida
:Osteostraci
Gnathostomata (jawed vertebrates)
:Placodermi
:Chondrichthyes (cartilaginous fish)
:Acanthodii
:Osteichthyes (bony fish)
::Actinopterygii (ray-finned fish)
::Sarcopterygii (lobe-finned fish)
:::Actinistia (coelacanths)
:::Dipnoi (lungfish)
:::Tetrapoda ::::Amphibia
::::Amniota
:::::Sauropsida/(Reptiles)
::::::Aves (Birds)
:::::Synapsida
::::::Mammalia Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. Vertebrates started to evolve about 530 million years ago during the Cambrian explosion, which is part of the Cambrian period (first known vertebrate is Myllokunmingia). The bones of the spinal column (or vertebral column) are called vertebrae. Vertebrata is the largest subphylum of chordates, and contains most animals with which people are generally familiar (except insects). Fish (including lampreys, but traditionally not hagfish, though this is now disputed), amphibians, reptiles, birds, and mammals (including humans) are vertebrates. Additional characteristics of the subphylum are a muscular system that mostly consists of paired masses, as well as a central nervous system which is partly located inside the backbone. The internal skeleton which defines vertebrates consists of cartilage or bone, or in some cases both. The skeleton provides support to the organism during the period of growth. For this reason vertebrates can achieve larger sizes than invertebrates, and on average vertebrates are in fact larger. The skeleton of most vertebrates, that is excluding the most primitive ones, consists of a skull, the vertebral column and two pairs of limbs. In some forms of vertebrates, one or both of these pairs of limbs may be absent, such as in snakes or whales. These limbs have been lost in the course of evolution. The skull is thought to have facilitated the development of intelligence as it protects vital organs such as the brain, the eyes and the ears. The protection of these organs is also thought to have positively influenced the development of high responsiveness to the environment often found in vertebrates. Both the vertebral column and the limbs support the body of the vertebrate overall. This support facilitates movement. Movement is normally achieved with muscles that are attached directly to the bones or cartilages. The contour of the body of a vertebrate is formed by the muscles. A skin covers the inner parts of a vertebrate's body. The skin sometimes acts as a structure for protective features, such as horny scales or fur. Feathers are also attached to the skin. The trunk of a vertebrate is hollow and houses the internal organs. The heart and the respiratory organs are protected in the trunk. The heart is located behind the gills, or where there are lungs, in between the lungs. The central nervous system of a vertebrate consists of the brain and the spinal cord. Both of these are characterized by being hollow. In lower vertebrates the brain mostly controls the functioning of the sense organs. In higher vertebrates the size of the brain relative to the size of the body is larger. This larger brain enables more intensive exchange of information between the different parts of the brain. The nerves from the spinal cord, which lies behind the brain, extend to the skin, the inner organs and the muscles. Some nerves are directly connected to the brain, linking the brain with the ears and lungs. Vertebrates have been traced back to the ostracoderms of the Silurian Period (444 million to 409 million years ago) and the conodonts, a group of eel-like vertebrates characterized by multiple pairs of bony toothplates. All vertebrates have: the ability to form bones; paired, specialised sensory organs and a brain.

External links


- [http://tolweb.org/tree?group=Amniota&contgroup=Terrestrial_vertebrates Tree of Life]
- [http://reference.allrefer.com/encyclopedia/categories/vertz.html Vertebrate Zoology] Category:Chordates ko:척추동물 ms:Vertebrata ja:脊椎動物 simple:Vertebrate th:สัตว์มีกระดูกสันหลัง

Conodonta

Conodonts are extinct worm-like forms with distinctive conical or multi-denticulate teeth made of apatite (calcium phosphate). The animals are sometimes referred to as conodontophora ("bearers of conodonts"), taking the word "conodont" to refer to the teeth themselves, but the strictly correct name for the animal group is 'Conodonta'. These tiny teeth are quite common in Paleozoic rocks and sands (250 to 500 million years old), but body fossils were not found until the early 1980s. The teeth (or more formally "elements") show complex, specialized structures, and survived through the ages and the fossilization process due to their resilient phosphatic chemical composition. Conodonts and their presumed relatives are known from the Cambrian to the Late Triassic. The earliest forms are identified as protoconodonts, followed by paraconodonts, followed by euconodonts (or "true conodonts"). Following the discovery of eleven body fossils in Scotland and South Africa, most paleontologists think conodonts — which turn out to have fins with fin rays, chevron shaped muscles, a stiffening chord that is the precursor of the backbone, and eyes — are in the phylum Chordata. Conodonts are today generally thought to be chordates/vertebrates but debate exists. Milsom and Rigby (2004) consider them vertebrates similar in appearance to modern hagfish and lamprays. Most paleontologists (following Szaniawski) place the protoconodonts in a phylum along with the chaetognath worms, indicating that they are not close relatives of the true conodonts. Complete fossils are rare, but the eleven imprints that have been found show an eel-like creature with 15 or, more rarely, 19 elements forming a bilaterally symmetrical array in the head, comprising a feeding apparatus radically different from the jaws of modern animals. Cladistic analyses by Donoghue et. al (1998, 2000) suggest that conodonts are vertebrates. The paraconodonts (known only from teeth) are thought to be related, but the relationship is unclear. According to Donoghue, protoconodonts are not related to the rest. Conodont teeth are phosphatic and their colour changes with the temperature at burial (and are therefore used as a proxy for thermal alteration in the host rock). Teeth are of three forms: coniform (cones), ramiform (bars), and pectiniform (platforms).

External links and references


- http://animaldiversity.ummz.umich.edu/site/accounts/information/Vertebrata.html
- http://tolweb.org/tree?group=Euconodonta&contgroup=Vertebrate
- http://www.le.ac.uk/geology/map2/map2stuff/model.html
- http://www.geocities.com/CapeCanaveral/Hall/1383/2TopCone.htm
- http://geology.csusb.edu/faculty/wbl/cdont_art.htm
- http://www.nhm.ac.uk/palaeontology/micro/collections/conodont/
- Aldridge, R. J., Briggs, D. E. G., Smith, M. P., Clarkson, E. N. K. & Clark, N. D. L. (1993), The anatomy of conodonts. "Philosophical Transactions of the Royal Society of London, Series B", 340, 405-421.
- Aldridge, R. J. & Purnell, M. A. (1996). The conodont controversies. "Trends in Ecology and Evolution", 11, 463-468.
- Donoghue, P. C. J., Purnell, M. A., & Aldridge, R. J. (1998), Conodont anatomy, chordate phylogeny and vertebrate classification. Lethaia, 31, 211-219.
- Donoghue, P. C. J., Forey, P. L. & Aldridge, R. J. (2000), Conodont affinity and chordate phylogeny. "Biological Reviews". 75, 191-251.
- Milsom, C. & Rigby, S (2004). Fossils at a Glance. Victoria, Australia: Blackwell Publishing, 155 pp. Category:Fossils ja:コノドント

Petromyzontidae

:This article is about the fish. Lamprey is also the name of a series of characters in the G.I. Joe Universe. 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. In zoology, lampreys are not considered to be true fish because of their vastly different morphology and physiology.

Physical description

Lampreys live mostly in coastal and fresh waters, although at least one species, Geotria australis, probably travels significant distances in the open ocean, as is evidenced by the lack of reproductive isolation between Australian and New Zealand populations, and the capture of a specimen in the Southern Ocean between Australia and Antarctica. They are found in most temperate regions except Africa. Their larvae have a low tolerance for high water temperatures, which is probably the reason that they are not found in the tropics. Outwardly resembling eels in that they have no scales, an adult lamprey can range anywhere from 5 to 40 inches (13 to 100 centimetres) long. Lampreys have one or two dorsal fins, large eyes, one nostril on the top of their head, and seven gills on each side. A lamprey has cartilage instead of bones and is on the borderline between vertebrates and invertebrates. invertebrates Lampreys begin life as burrowing freshwater larvae (ammocoetes). At this stage, they are toothless, have rudimentary eyes, and feed on microorganisms. This larval stage can last five to seven years and hence was originally thought to be an independent organism. After these five to seven years, they transform into adults in a metamorphosis which is at least as radical as that seen in amphibians, and which involves a radical rearrangement of internal organs, development of eyes and transformation from a mud-dwelling filter feeder into an efficient swimming predator, which typically moves into the sea to begin a predatory/parasitic life, attaching to a fish by their mouths and feeding on the blood and tissues of the host. In most species this phase lasts about 18 months. Whether lampreys are predators or parasites is a blurred question. Not all lampreys can be found in the sea. Some lampreys are landlocked and remain in fresh water, and some of these stop feeding altogether as soon as they have left the larval stage. The landlocked species are usually rather small. To reproduce, lampreys return to fresh water (if they left it), build a nest, then spawn, that is, lay their eggs or excrete their semen, and then invariably die. In Geotria australis, the time between ceasing to feed at sea and spawning can be up to 18 months long—surely one of the most remarkable endurance events in the animal kingdom. Recent studies reported in Nature suggest that lampreys have evolved a unique type of immune system with parts that are unrelated to the antibodies found in mammals. They also have a very high tolerance to iron overload, and have evolved biochemical defenses to detoxify this metal.

Taxonomy

The taxonomy presented here is that given by Fisher, 1994. The lampreys comprise an entire class Cephalaspidomorphi, containing a single order Petromyzontiformes and family Petromyzontidae. Within this family, there are 40 recorded species in 9 genera and 3 subfamilies:
- Subfamily Geotriianae
  - Genus Geotria
    - Geotria australis (Gray,1851)
- Subfamily Mordaciinae
  - Genus Mordacia
    - Mordacia lapicida (Gray, 1851)
    - Mordacia mordax (Richardson, 1846)
    - Mordacia praecox (Potter, 1968)
- Subfamily Petromyzontinae
  - Genus Caspiomyzon
    - Caspiomyzon wagneri (Kessler, 1870)
  - Genus Eudontomyzon
    - Eudontomyzon danfordi (Regan, 1911)
    - Eudontomyzon hellenicus (Vladykov, Renaud, Kott and Economidis, 1982)
    - Eudontomyzon mariae (Berg, 1931)
    - Eudontomyzon morii (Berg, 1931)
    - Eudontomyzon stankokaramani (Karaman, 1974)
    - Eudontomyzon vladykovi (Oliva and Zanandrea, 1959)
  - Genus Ichthyomyzon
    - Ichthyomyzon bdellium (Jordan, 1885) - Ohio Lamprey
    - Ichthyomyzon castaneus Girard, 1858 - Chestnut Lamprey
    - Ichthyomyzon fossor (Reighard and Cummins, 1916) - Northern Brook Lamprey
    - Ichthyomyzon gagei (Hubbs and Trautman, 1937) - Southern Brook Lamprey
    - Ichthyomyzon greeleyi (Hubbs and Trautman, 1937) - Mountain Brook Lamprey
    - Ichthyomyzon unicuspis (Hubbs and Trautman, 1937) - Silver Lamprey
  - Genus Lampetra
    - Lampetra aepyptera (Abbott, 1860) - Least Brook lamprey
    - Lampetra alaskensis (Vladykov and Kott, 1978)
    - Lampetra appendix (DeKay, 1842) - American Brook Lamprey
    - Lampetra ayresii (Günther, 1870)
    - Lampetra fluviatilis (Linnaeus, 1758)
    - Lampetra hubbsi (Vladykov and Kott, 1976) - Kern Brook lamprey
    - Lampetra lamottei (Lesueur, 1827)
    - Lampetra lanceolata (Kux and Steiner, 1972)
    - Lampetra lethophaga (Hubbs, 1971) - Pit-Klamath Brook Lamprey
    - Lampetra macrostoma (Beamish, 1982) - Vancouver Lamprey
    - Lampetra minima (Bond and Kan, 1973) - Miller Lake Lamprey
    - Lampetra planeri (Bloch, 1784)
    - Lampetra richardsoni (Vladykov and Follett, 1965) - Western Brook Lamprey
    - Lampetra similis (Vladykov and Kott, 1979) - Klamath Lamprey
    - Lampetra tridentata (Richardson, 1836) - Pacific Lamprey
  - Genus Lethenteron
    - Lethenteron camtschaticum (Tilesius, 1811)
    - Lethenteron japonicum (Martens, 1868)
    - Lethenteron kessleri (Anikin, 1905)
    - Lethenteron matsubarai (Vladykov and Kott, 1978)
    - Lethenteron reissneri (Dybowski, 1869)
    - Lethenteron zanandreai (Vladykov, 1955)
  - Genus Petromyzon
    - Petromyzon marinus (Linnaeus, 1758) - Sea Lamprey
  - Genus Tetrapleurodon
    - Tetrapleurodon geminis (Alvarez, 1964)
    - Tetrapleurodon spadiceus (Bean, 1887) Notes:
- Cephalaspidomorpha is sometimes given as a subclass of the Cephalaspidomorphi.
- Petromyzoniformes and Petromyzonidae are sometimes used as alternative spellings for Petromyzontiformes and Petromyzontidae respectively.

Relation to humans

Lampreys have long been used as food for humans. During the Middle Ages, they were widely eaten by the upper classes throughout Europe, especially during fasting periods, since their taste is much meatier than that of most true fish. King Henry I of England is said to have died from eating spoiled lampreys. Especially in Southwestern Europe (Portugal, Spain, France) they are still a highly prized delicacy and fetch up to $25 a pound. Overfishing has reduced their number in those parts. France On the other hand, lampreys have become a major plague in the North American Great Lakes after artificial canals allowed their entry during the early 20th century. They have no natural enemies in the lakes and prey on many species of commercial value, such as trouts. Since North American consumers, unlike Europeans, refuse to accept lampreys as food fish, the Great Lakes fishery has been very adversely affected by their invasion. They are now fought mostly in the streams that feed the lakes, with special barriers and special poisons called lampricides, which are harmless to other species (as lampreys are not true fish). However those programs are complicated and expensive, and they do not eradicate the lampreys from the lakes but merely keep them in check. New programs are being developed including the use of sterilization of male lamprey, trapping of prespawn adults. Research is currently under way on the use of pheremones and how they may be used to disrupt the life cycle.(Sorensen, et al., 2005) Control of sea lamprey in the Great Lakes is conducted by the U.S. Fish and Wildlife Service and the Canadian Department of Fisheries and Oceans. The work is coordinated by the Great Lakes Fishery Commission.

References


- [http://www.itis.usda.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=159697 ITIS report on the lampreys]
- [http://www.sciencenews.org/pages/sn_arch/8_10_96/food.htm Lampreys as food, including recipes]
- [http://www.nature.com/nchembio/journal/v1/n6/abs/nchembio739.html Abstract]
- Category:Vertebrates without jaws ja:ヤツメウナギ

Lamprey

:This article is about the fish. Lamprey is also the name of a series of characters in the G.I. Joe Universe. 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. In zoology, lampreys are not considered to be true fish because of their vastly different morphology and physiology.

Physical description

Lampreys live mostly in coastal and fresh waters, although at least one species, Geotria australis, probably travels significant distances in the open ocean, as is evidenced by the lack of reproductive isolation between Australian and New Zealand populations, and the capture of a specimen in the Southern Ocean between Australia and Antarctica. They are found in most temperate regions except Africa. Their larvae have a low tolerance for high water temperatures, which is probably the reason that they are not found in the tropics. Outwardly resembling eels in that they have no scales, an adult lamprey can range anywhere from 5 to 40 inches (13 to 100 centimetres) long. Lampreys have one or two dorsal fins, large eyes, one nostril on the top of their head, and seven gills on each side. A lamprey has cartilage instead of bones and is on the borderline between vertebrates and invertebrates. invertebrates Lampreys begin life as burrowing freshwater larvae (ammocoetes). At this stage, they are toothless, have rudimentary eyes, and feed on microorganisms. This larval stage can last five to seven years and hence was originally thought to be an independent organism. After these five to seven years, they transform into adults in a metamorphosis which is at least as radical as that seen in amphibians, and which involves a radical rearrangement of internal organs, development of eyes and transformation from a mud-dwelling filter feeder into an efficient swimming predator, which typically moves into the sea to begin a predatory/parasitic life, attaching to a fish by their mouths and feeding on the blood and tissues of the host. In most species this phase lasts about 18 months. Whether lampreys are predators or parasites is a blurred question. Not all lampreys can be found in the sea. Some lampreys are landlocked and remain in fresh water, and some of these stop feeding altogether as soon as they have left the larval stage. The landlocked species are usually rather small. To reproduce, lampreys return to fresh water (if they left it), build a nest, then spawn, that is, lay their eggs or excrete their semen, and then invariably die. In Geotria australis, the time between ceasing to feed at sea and spawning can be up to 18 months long—surely one of the most remarkable endurance events in the animal kingdom. Recent studies reported in Nature suggest that lampreys have evolved a unique type of immune system with parts that are unrelated to the antibodies found in mammals. They also have a very high tolerance to iron overload, and have evolved biochemical defenses to detoxify this metal.

Taxonomy

The taxonomy presented here is that given by Fisher, 1994. The lampreys comprise an entire class Cephalaspidomorphi, containing a single order Petromyzontiformes and family Petromyzontidae. Within this family, there are 40 recorded species in 9 genera and 3 subfamilies:
- Subfamily Geotriianae
  - Genus Geotria
    - Geotria australis (Gray,1851)
- Subfamily Mordaciinae
  - Genus Mordacia
    - Mordacia lapicida (Gray, 1851)
    - Mordacia mordax (Richardson, 1846)
    - Mordacia praecox (Potter, 1968)
- Subfamily Petromyzontinae
  - Genus Caspiomyzon
    - Caspiomyzon wagneri (Kessler, 1870)
  - Genus Eudontomyzon
    - Eudontomyzon danfordi (Regan, 1911)
    - Eudontomyzon hellenicus (Vladykov, Renaud, Kott and Economidis, 1982)
    - Eudontomyzon mariae (Berg, 1931)
    - Eudontomyzon morii (Berg, 1931)
    - Eudontomyzon stankokaramani (Karaman, 1974)
    - Eudontomyzon vladykovi (Oliva and Zanandrea, 1959)
  - Genus Ichthyomyzon
    - Ichthyomyzon bdellium (Jordan, 1885) - Ohio Lamprey
    - Ichthyomyzon castaneus Girard, 1858 - Chestnut Lamprey
    - Ichthyomyzon fossor (Reighard and Cummins, 1916) - Northern Brook Lamprey
    - Ichthyomyzon gagei (Hubbs and Trautman, 1937) - Southern Brook Lamprey
    - Ichthyomyzon greeleyi (Hubbs and Trautman, 1937) - Mountain Brook Lamprey
    - Ichthyomyzon unicuspis (Hubbs and Trautman, 1937) - Silver Lamprey
  - Genus Lampetra
    - Lampetra aepyptera (Abbott, 1860) - Least Brook lamprey
    - Lampetra alaskensis (Vladykov and Kott, 1978)
    - Lampetra appendix (DeKay, 1842) - American Brook Lamprey
    - Lampetra ayresii (Günther, 1870)
    - Lampetra fluviatilis (Linnaeus, 1758)
    - Lampetra hubbsi (Vladykov and Kott, 1976) - Kern Brook lamprey
    - Lampetra lamottei (Lesueur, 1827)
    - Lampetra lanceolata (Kux and Steiner, 1972)
    - Lampetra lethophaga (Hubbs, 1971) - Pit-Klamath Brook Lamprey
    - Lampetra macrostoma (Beamish, 1982) - Vancouver Lamprey
    - Lampetra minima (Bond and Kan, 1973) - Miller Lake Lamprey
    - Lampetra planeri (Bloch, 1784)
    - Lampetra richardsoni (Vladykov and Follett, 1965) - Western Brook Lamprey
    - Lampetra similis (Vladykov and Kott, 1979) - Klamath Lamprey
    - Lampetra tridentata (Richardson, 1836) - Pacific Lamprey
  - Genus Lethenteron
    - Lethenteron camtschaticum (Tilesius, 1811)
    - Lethenteron japonicum (Martens, 1868)
    - Lethenteron kessleri (Anikin, 1905)
    - Lethenteron matsubarai (Vladykov and Kott, 1978)
    - Lethenteron reissneri (Dybowski, 1869)
    - Lethenteron zanandreai (Vladykov, 1955)
  - Genus Petromyzon
    - Petromyzon marinus (Linnaeus, 1758) - Sea Lamprey
  - Genus Tetrapleurodon
    - Tetrapleurodon geminis (Alvarez, 1964)
    - Tetrapleurodon spadiceus (Bean, 1887) Notes:
- Cephalaspidomorpha is sometimes given as a subclass of the Cephalaspidomorphi.
- Petromyzoniformes and Petromyzonidae are sometimes used as alternative spellings for Petromyzontiformes and Petromyzontidae respectively.

Relation to humans

Lampreys have long been used as food for humans. During the Middle Ages, they were widely eaten by the upper classes throughout Europe, especially during fasting periods, since their taste is much meatier than that of most true fish. King Henry I of England is said to have died from eating spoiled lampreys. Especially in Southwestern Europe (Portugal, Spain, France) they are still a highly prized delicacy and fetch up to $25 a pound. Overfishing has reduced their number in those parts. France On the other hand, lampreys have become a major plague in the North American Great Lakes after artificial canals allowed their entry during the early 20th century. They have no natural enemies in the lakes and prey on many species of commercial value, such as trouts. Since North American consumers, unlike Europeans, refuse to accept lampreys as food fish, the Great Lakes fishery has been very adversely affected by their invasion. They are now fought mostly in the streams that feed the lakes, with special barriers and special poisons called lampricides, which are harmless to other species (as lampreys are not true fish). However those programs are complicated and expensive, and they do not eradicate the lampreys from the lakes but merely keep them in check. New programs are being developed including the use of sterilization of male lamprey, trapping of prespawn adults. Research is currently under way on the use of pheremones and how they may be used to disrupt the life cycle.(Sorensen, et al., 2005) Control of sea lamprey in the Great Lakes is conducted by the U.S. Fish and Wildlife Service and the Canadian Department of Fisheries and Oceans. The work is coordinated by the Great Lakes Fishery Commission.

References


- [http://www.itis.usda.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=159697 ITIS report on the lampreys]
- [http://www.sciencenews.org/pages/sn_arch/8_10_96/food.htm Lampreys as food, including recipes]
- [http://www.nature.com/nchembio/journal/v1/n6/abs/nchembio739.html Abstract]
- Category:Vertebrates without jaws ja:ヤツメウナギ

Pteraspidomorphi

Pteraspidomorphi is an extinct taxon of early jawless fish. The fossils show extensive shielding of the head. Maybe some species even lived in fresh water. They are considered as vertebrates. The taxon contains the subgroups Heterostraci, Astraspida, Arandaspida and Eriptychiida.

See also


- http://tolweb.org/tree?group=Pteraspidomorphi&contgroup=Vertebrate
- Fish Category:Paleontology

Thelodonti

Coelolepida (Thelodonti) are very similar to the Heterostraci but are brackish water dwellers. They are covered with small spiny scales. They lived during the Silurian and Devonian periods. They are an extinct vertebrate subgroup of the agnatha.

See also

Thelodontidae

Anaspida

Anaspida are a extinct marine subgroup of the agnatha. They lived from the Early Silurian to the Late Devonian times. Anaspida are similar to the Osteostraci and had unpaired fins.

Cephalaspidomorphi

:This article is about the fish. Lamprey is also the name of a series of characters in the G.I. Joe Universe. 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. In zoology, lampreys are not considered to be true fish because of their vastly different morphology and physiology.

Physical description

Lampreys live mostly in coastal and fresh waters, although at least one species, Geotria australis, probably travels significant distances in the open ocean, as is evidenced by the lack of reproductive isolation between Australian and New Zealand populations, and the capture of a specimen in the Southern Ocean between Australia and Antarctica. They are found in most temperate regions except Africa. Their larvae have a low tolerance for high water temperatures, which is probably the reason that they are not found in the tropics. Outwardly resembling eels in that they have no scales, an adult lamprey can range anywhere from 5 to 40 inches (13 to 100 centimetres) long. Lampreys have one or two dorsal fins, large eyes, one nostril on the top of their head, and seven gills on each side. A lamprey has cartilage instead of bones and is on the borderline between vertebrates and invertebrates. invertebrates Lampreys begin life as burrowing freshwater larvae (ammocoetes). At this stage, they are toothless, have rudimentary eyes, and feed on microorganisms. This larval stage can last five to seven years and hence was originally thought to be an independent organism. After these five to seven years, they transform into adults in a metamorphosis which is at least as radical as that seen in amphibians, and which involves a radical rearrangement of internal organs, development of eyes and transformation from a mud-dwelling filter feeder into an efficient swimming predator, which typically moves into the sea to begin a predatory/parasitic life, attaching to a fish by their mouths and feeding on the blood and tissues of the host. In most species this phase lasts about 18 months. Whether lampreys are predators or parasites is a blurred question. Not all lampreys can be found in the sea. Some lampreys are landlocked and remain in fresh water, and some of these stop feeding altogether as soon as they have left the larval stage. The landlocked species are usually rather small. To reproduce, lampreys return to fresh water (if they left it), build a nest, then spawn, that is, lay their eggs or excrete their semen, and then invariably die. In Geotria australis, the time between ceasing to feed at sea and spawning can be up to 18 months long—surely one of the most remarkable endurance events in the animal kingdom. Recent studies reported in Nature suggest that lampreys have evolved a unique type of immune system with parts that are unrelated to the antibodies found in mammals. They also have a very high tolerance to iron overload, and have evolved biochemical defenses to detoxify this metal.

Taxonomy

The taxonomy presented here is that given by Fisher, 1994. The lampreys comprise an entire class Cephalaspidomorphi, containing a single order Petromyzontiformes and family Petromyzontidae. Within this family, there are 40 recorded species in 9 genera and 3 subfamilies:
- Subfamily Geotriianae
  - Genus Geotria
    - Geotria australis (Gray,1851)
- Subfamily Mordaciinae
  - Genus Mordacia
    - Mordacia lapicida (Gray, 1851)
    - Mordacia mordax (Richardson, 1846)
    - Mordacia praecox (Potter, 1968)
- Subfamily Petromyzontinae
  - Genus Caspiomyzon
    - Caspiomyzon wagneri (Kessler, 1870)
  - Genus Eudontomyzon
    - Eudontomyzon danfordi (Regan, 1911)
    - Eudontomyzon hellenicus (Vladykov, Renaud, Kott and Economidis, 1982)
    - Eudontomyzon mariae (Berg, 1931)
    - Eudontomyzon morii (Berg, 1931)
    - Eudontomyzon stankokaramani (Karaman, 1974)
    - Eudontomyzon vladykovi (Oliva and Zanandrea, 1959)
  - Genus Ichthyomyzon
    - Ichthyomyzon bdellium (Jordan, 1885) - Ohio Lamprey
    - Ichthyomyzon castaneus Girard, 1858 - Chestnut Lamprey
    - Ichthyomyzon fossor (Reighard and Cummins, 1916) - Northern Brook Lamprey
    - Ichthyomyzon gagei (Hubbs and Trautman, 1937) - Southern Brook Lamprey
    - Ichthyomyzon greeleyi (Hubbs and Trautman, 1937) - Mountain Brook Lamprey
    - Ichthyomyzon unicuspis (Hubbs and Trautman, 1937) - Silver Lamprey
  - Genus Lampetra
    - Lampetra aepyptera (Abbott, 1860) - Least Brook lamprey
    - Lampetra alaskensis (Vladykov and Kott, 1978)
    - Lampetra appendix (DeKay, 1842) - American Brook Lamprey
    - Lampetra ayresii (Günther, 1870)
    - Lampetra fluviatilis (Linnaeus, 1758)
    - Lampetra hubbsi (Vladykov and Kott, 1976) - Kern Brook lamprey
    - Lampetra lamottei (Lesueur, 1827)
    - Lampetra lanceolata (Kux and Steiner, 1972)
    - Lampetra lethophaga (Hubbs, 1971) - Pit-Klamath Brook Lamprey
    - Lampetra macrostoma (Beamish, 1982) - Vancouver Lamprey
    - Lampetra minima (Bond and Kan, 1973) - Miller Lake Lamprey
    - Lampetra planeri (Bloch, 1784)
    - Lampetra richardsoni (Vladykov and Follett, 1965) - Western Brook Lamprey
    - Lampetra similis (Vladykov and Kott, 1979) - Klamath Lamprey
    - Lampetra tridentata (Richardson, 1836) - Pacific Lamprey
  - Genus Lethenteron
    - Lethenteron camtschaticum (Tilesius, 1811)
    - Lethenteron japonicum (Martens, 1868)
    - Lethenteron kessleri (Anikin, 1905)
    - Lethenteron matsubarai (Vladykov and Kott, 1978)
    - Lethenteron reissneri (Dybowski, 1869)
    - Lethenteron zanandreai (Vladykov, 1955)
  - Genus Petromyzon
    - Petromyzon marinus (Linnaeus, 1758) - Sea Lamprey
  - Genus Tetrapleurodon
    - Tetrapleurodon geminis (Alvarez, 1964)
    - Tetrapleurodon spadiceus (Bean, 1887) Notes:
- Cephalaspidomorpha is sometimes given as a subclass of the Cephalaspidomorphi.
- Petromyzoniformes and Petromyzonidae are sometimes used as alternative spellings for Petromyzontiformes and Petromyzontidae respectively.

Relation to humans

Lampreys have long been used as food for humans. During the Middle Ages, they were widely eaten by the upper classes throughout Europe, especially during fasting periods, since their taste is much meatier than that of most true fish. King Henry I of England is said to have died from eating spoiled lampreys. Especially in Southwestern Europe (Portugal, Spain, France) they are still a highly prized delicacy and fetch up to $25 a pound. Overfishing has reduced their number in those parts. France On the other hand, lampreys have become a major plague in the North American Great Lakes after artificial canals allowed their entry during the early 20th century. They have no natural enemies in the lakes and prey on many species of commercial value, such as trouts. Since North American consumers, unlike Europeans, refuse to accept lampreys as food fish, the Great Lakes fishery has been very adversely affected by their invasion. They are now fought mostly in the streams that feed the lakes, with special barriers and special poisons called lampricides, which are harmless to other species (as lampreys are not true fish). However those programs are complicated and expensive, and they do not eradicate the lampreys from the lakes but merely keep them in check. New programs are being developed including the use of sterilization of male lamprey, trapping of prespawn adults. Research is currently under way on the use of pheremones and how they may be used to disrupt the life cycle.(Sorensen, et al., 2005) Control of sea lamprey in the Great Lakes is conducted by the U.S. Fish and Wildlife Service and the Canadian Department of Fisheries and Oceans. The work is coordinated by the Great Lakes Fishery Commission.

References


- [http://www.itis.usda.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=159697 ITIS report on the lampreys]
- [http://www.sciencenews.org/pages/sn_arch/8_10_96/food.htm Lampreys as food, including recipes]
- [http://www.nature.com/nchembio/journal/v1/n6/abs/nchembio739.html Abstract]
- Category:Vertebrates without jaws ja:ヤツメウナギ

Galeaspida

Galeaspida (galeaspids) are an extinct taxon of jawless marine fish and a subgroup of the Cephalaspidomorphi, which are itself a subgroup of the vertebrate. They lived in Silurian and Devonian times (430 to 370 million years ago). All fossils were found in Asia. Galeaspids are separated in Eugaleaspidiformes and Polybranchiaspidida. The name Galeaspida is derived from a latin word for helmet, galea. This refers to their massive bone shield on the head.

See also


- Osteostraci
- http://tolweb.org/tree?group=Galeaspida

Pituriaspida

Pituriaspida are an extinct taxon of jawless marine fish and a subgroup of the Cephalaspidomorphi, which are itself a subgroup of the vertebrate. Fossils were found in Australia. The are deivided in the group Pituriaspis and Neeyambaspis.

See also


- http://tolweb.org/tree?group=Pituriaspida Category:Paleontology

Osteostraci

Osteostraci (Cephalaspidiformes) are an extinct marine subgroup of the agnatha. They lived from the Middle Silurian to Late Devonian. Osteostraci possessed paired fin-like structures.

See also


- Anaspida

External links


- http://academic.emporia.edu/mooredwi/nathist/chap3.htm

Gnathostomata

For the echinoderm, see Gnathostomata (echinoid)
- Placodermi
- Chondrichthyes
- Acanthodii
- Osteichthyes Gnathostomata is the group of vertebrates with jaws. The group is traditionally a superclass, including the familiar classes of fish, birds, and so forth, and a sister group of the jawless vertebrates Agnatha. However, recent genetic studies are causing a reassessment of Gnathostomata as a grouping. Other distinguishing characteristics of living gnathostomates are the myelin sheathes of neurons, and an adaptive immune system. For the phylogenetic tree of Gnathostomata see chordate. The traditional classes of Gnathostomata include:
- Placodermi - extinct
- Chondrichthyes (cartilagenous fish)
- Acanthodii - extinct
- Osteichthyes (or Teleostomi) (bony fish)
  - subclass Sarcopterygii (lobe-finned fish)
  - subclass Actinopterygii (ray-finned fish)
- Amphibia (amphibians)
- Reptilia (reptiles)
- Aves (birds)
- Mammalia (mammals)

External link


- [http://tolweb.org/tree?group=Gnathostomata&contgroup=Vertebrata Tree of Life discussion of Gnathostomata] Category:Chordates Category:Vertebrates with Jaws

Chondrichthyes


see text The Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nostrils, scales, two-chambered hearts, and skeletons made of cartilage. They consist of several orders:
- Subclass Elasmobranchii (sharks, rays and skates)
  - Superorder Batoidea (rays and skates), containing the orders:
  - # Rajiformes (common rays and skates)
  - # Pristiformes (Sawfishes)
  - # Torpediniformes (electric rays)
  - Superorder Selachimorpha (sharks), containing the orders:
  - # Hexanchiformes Two families are found within this order. Species of this order are distinguished from other sharks by having additional gill slits (either six or seven). Examples from this group include the cow sharks, frilled shark and even a shark that looks on first inspection to be a marine snake.
  - # Squaliformes Three families and more than 80 species are found within this order. These sharks have two dorsal fins, often with spines, and no anal fin. They have teeth designed for cutting in both the upper and lower jaws. Examples from this group include the bramble sharks, dogfishes and roughsharks.
  - # Pristiophoriformes One family is found within this order. These are the sawsharks, with an elongate, toothed snout that they use for slashing the fishes that they then eat.
  - # Squatiniformes One family is found within this order. These are flattened sharks that can be distinguished from the similar appearing skates and rays by the fact that they have the gill slits along the side of the head like all other sharks. They have a caudal fin (tail) with the lower lobe being much longer in length than the upper, and are commonly referred to as angel sharks.
  - # Heterodontiformes One family is found within this order. They are commonly referred to as the bullhead, or horn sharks. They have a variety of teeth allowing them to grasp and then crush shellfishes.
  - # Orectolobiformes Seven families are found within this order. They are commonly referred to as the carpet sharks, including zebra sharks, nurse sharks, wobbegongs and the largest of all fishes, the whale sharks. They are distinguished by having barbels at the edge of the nostrils. Most, but not all are nocturnal.
  - # Carcharhiniformes Eight families are found within this order. It is the largest order, containing almost 200 species. They are commonly referred to as the groundsharks, and some of the species include the blue, tiger, bull, reef and oceanic white tipped sharks (collectively called the requiem sharks) along with the houndsharks, catsharks and hammerhead sharks. They are distinguished by an elongated snout and a nictitating membrane which protects the eyes during an attack.
  - # Lamniformes Seven families are found within this order. They are commonly referred to as the mackerel sharks. They include the goblin shark, basking shark, megamouth, the thresher, mako shark and great white shark. They are distinguished by their large jaws and ovoviviparous reproduction. The Lamniformes contains the extinct Megalodon (Carcharodon megalodon), which like all extinct sharks is only known by the teeth (the only bone found in these cartilaginous fishes, and therefore the only fossils produced). A reproduction of the jaw was based on some of the largest teeth (up to almost 7 inches in length) and suggested a fish that could grow 120 feet in length. The jaw was realized to be inaccurate, and estimates revised downwards to around 50 feet.
- Subclass Holocephali (chimaera)

References


- [http://www.fmnh.helsinki.fi/users/haaramo/Metazoa/Deuterostoma/Chordata/Chondrichthyes/Chondrichthyes.htm#Elasmobranchii Taxonomy of Chondrichthyes] Category:Chordates ko:연골어류 ja:軟骨魚綱

Acanthodii

Climatiiformes
Ischnacanthiformes
Acanthodiformes Acanthodii (sometimes called spiny sharks) is a class of extinct fishes, having features of both bony fish ( Osteichthyes) and cartilaginous fish (Chondrichthyes). They appeared in the early Silurian (430 mya) and lasted until the late Permian (250 mya). The earliest ancanthodians were marine, but during the Devonian, freshwater species became predominant. They are distinguished in two respects: they were the first known jawed vertebrates, and they had stout spines supporting their fins, fixed in place and non-movable (like a shark's dorsal fin). There were three orders: Climatiiformes, Ischnacanthiformes and Acanthodiformes. Climatiiforma had shoulder armor and many small sharp spines, Ischnacathiforma with teeth fused to the jaw, and the Acanthodiforma were filter feeders, with no teeth in the jaw, but long gill rakers. Almost all of them were small, slender fish with large eyes, heterocercal tails, with the caudal vertebrae supporting the top lobe of the tail fin, like a shark's tail has today. All had pairs of bony spines along the ventral mid-body line, that often supported a web of tissue between the spine and the body, creating a fin. Thus the "spiny shark" nickname. These distinctive spines give the class its name, from the Greek akanthos. The scales of Acanthodii are unique and used in determining relative age of sedimentary rock. The scales are tiny, with a bulbus base, a neck, and a flat or slightly curved diamond-shaped crown.

References

Long, J.A. The Rise of Fishes: 500 Million Years of Evolution. Johns Hopkins Univ. Press. Baltimore and London. 1995.

External links

http://www.mdgekko.com/devonian/who/pages/acanthodians.html Category:Prehistoric fish

Osteichthyes


See under classes: Actinopterygii and Sarcopterygii Class Osteichthyes are the bony fish, a group paraphyletic to the land vertebrates, which are sometimes included. Most belong to the Actinopterygii. The others are called lobe-finned fish, and include lungfish and coelacanths. They are traditionally treated as a class of vertebrates, with subclasses Actinopterygii and Sarcopterygii, but newer schemes may divide them into several separate classes. The vast majority of fish are bony fish, and therefore belong to class Osteichthyes. Osteichthians are characterized by a relatively stable pattern of cranial bones, rooted teeth, medial insertion of mandibular muscle in lower jaw. The head and pectoral girdles are covered with large dermal bones. The eyeball is supported by a sclerotic ring of four small bones, although this characteristic has been lost or modified in many modern species. The labyrinth in the inner ear contains large otoliths. The braincase, or neurocranium, is frequently divided into anterior and posterior sections divided by fissure. Osteichthyans possess a lung or swim bladder. They do not have fin spines, but instead support the fin with lepidotrichia (bone fin rays). One of the best-known innovations of the osteichthians is endochondral or "replacement" bone, i.e. bone ossified internally, by replacement of cartilage, as well as perichondrally, as "spongy bone." In the more general vertebrates there are various types of calcified tissues: dentine, enamel (or "enameloids") and bone, plus variants, characterized by their ontogeny, chemistry, form and location. However, endochondral bone is unique because it begins life as cartilage. In more basal vertebrates, cartilaginous structures can become superficially calcified. However, in osteichthians, the circulatory system actually invades the cartilaginous matrix. This permits the local osteoblasts (bone-forming cells) to continue bone formation within the cartilage and also recruits additional, circulating osteoblasts. Other cells gradually eat away at the surrounding cartilage. The net result is that the cartilage is replaced from within by a somewhat irregular vascularized network of bone. Structurally, the effect is to create a relatively lightweight, flexible, "spongy" bone interior, surrounded by an outline of dense, lamellar periostial bone (since this bone now surrounds other bone, rather than cartilage, it is referred to as periostial rather than perichondral). This is the unique endochondral bone from which the osteichthians derived their name, as well as countless structural advantages. However useful endochondral bone may be, it is also much heavier and less flexible than cartilage. Thus, many modern osteichian groups, including the extremely successful teleosts, have evolved away from extensive use of endochondral bone. The question of the largest bony fish or osteichthian is an interesting one. Contenders for the title include the Blue Marlin, that have been relatively reliably recorded to weights in excess of 820 kilograms, and several sturgeon species.

See also


- Ostracoderm - the first bony fishes. ko:경골어류 ja:硬骨魚綱

Actinopterygii


Chondrostei
Neopterygii
See text for orders. The Actinopterygii are the ray-finned fish. They are the dominant group of vertebrates, with over 27,000 species ubiquitous throughout fresh water and marine environments.

Classification

Traditionally three grades of Actinopterygii have been recognized: the Chondrostei, Holostei, and Teleostei. The second is paraphyletic and tends to be abandoned, however, while the first is now restricted to those forms closer to extant Chondrostei than to the other groups. Nearly all fish alive today are teleosts. A listing of the different groups is given below, down to the level of orders, arranged in what is believed to represent the evolutionary sequence down to the level of superorder.
- Subclass Chondrostei
  - Order Polypteriformes (bichirs)
  - Order Acipenseriformes (sturgeons, paddlefish)
- Subclass Neopterygii
  - Order Semionotiformes (gars)
  - Order Amiiformes (bowfins)
  - Infraclass Teleostei
    - Superorder Osteoglossomorpha
      - Order Osteoglossiformes (bony tongues, etc)
      - Order Hiodontiformes (mooneye, etc)
    - Superorder Elopomorpha
      - Order Elopiformes (tarpons, etc)
      - Order Albuliformes (bonefishes)
      - Order Notacanthiformes (spiny eels)
      - Order Anguilliformes (true eels, gulpers)
      - Order Saccopharyngiformes
    - Superorder Clupeomorpha
      - Order Clupeiformes (herrings & allies)
    - Superorder Ostariophysi
      - Order Gonorynchiformes
      - Order Cypriniformes (minnows & allies)
      - Order Characiformes (characins & allies)
      - Order Gymnotiformes (electric eels, knifefishes)
      - Order Siluriformes (catfishes)
    - Superorder Protacanthopterygii
      - Order Salmoniformes (salmon & allies)
      - Order Esociformes (pikes & allies)
      - Order Osmeriformes (smelts & allies)
    - Superorder Sternopterygii
      - Order Ateleopodiformes (jellynose fishes)
      - Order Stomiiformes (dragonfishes & allies)
    - Superorder Cyclosquamata
      - Order Aulopiformes (lizardfishes)
    - Superorder Scopelomorpha
      - Order Myctophiformes (lanternfishes)
    - Superorder Lampridiomorpha
      - Order Lampridiformes (opahs, etc)
    - Superorder Polymyxiomorpha
      - Order Polymixiiformes (beardfishes)
    - Superorder Paracanthopterygii
      - Order Percopsiformes (trout-perches & allies)
      - Order Batrachoidiformes (toadfishes)
      - Order Lophiiformes (goosefishes, etc)
      - Order Gadiformes (cods & allies)
      - Order Ophidiiformes (cusk eels, etc)
    - Superorder Acanthopterygii
      - Order Mugiliformes (mullets & allies)
      - Order Atheriniformes (silversides & allies)
      - Order Beloniformes (needlefishes, etc)
      - Order Cetomimiformes (whalefishes)
      - Order Cyprinodontiformes (killifishes, etc)
      - Order Stephanoberyciformes (pricklefishes, whalefishes, etc)
      - Order Beryciformes (alfonsinos, etc)
      - Order Zeiformes (dories, etc)
      - Order Gasterosteiformes (sticklebacks, pipefishes, seahorses, etc)
      - Order Synbranchiformes (swamp-eels, etc)
      - Order Tetraodontiformes (triggerfishes & allies)
      - Order Pleuronectiformes (flatfishes & allies)
      - Order Scorpaeniformes (scorpionfishes & allies)
      - Order Perciformes (perches & many allies)

External links


-
- [http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?name=actinopterygii NCBI Taxonomy entry]

References


- Category:Bony fish ko:조기어류 ja:条鰭亜綱

Sarcopterygii

Coelacanthimorpha - Coelacanths
Dipnoi - Lungfishes
Tetrapoda Sarcopterygii (from Greek sarx, flesh, and pteryx, fin) is traditionally the class of lobe-finned fishes, consisting of lungfish and coelacanths. Most taxonomists who subscribe to the cladistic approach include within this group the subclass Tetrapoda, which in turns consists of all species of four-limbed vertebrates:
- Coelacanthimorpha
  - Coelacanthiformes
- Rhipidistia
  - Dipnoi
    - Ceratodontimorpha
  - Tetrapoda
    - Amniota
      - Mammalia
      - Sauropsida
    - Amphibia
      - Batrachia
      - Gymnophiona This level of taxonomy is in flux however; the membership of Sarcopterygii is likely to change, and it may even be discontinued as a classification. Category:Bony fish

Coelacanth


Latimeria chalumnae
Latimeria menadoensis Coelacanth (meaning "hollow spine" in Greek; ) is a species of fish and represents the oldest lineage of living fish known to date. The coelacanth was believed to have been extinct since the end of the Cretaceous period — until a live specimen turned up off the east coast of South Africa off the Chalumna River in 1938. Since then, they have been found in the Comoros, Sulawesi (Indonesia), Kenya, Tanzania, Mozambique, Madagascar and the St. Lucia Marine Protected Area in South Africa.

Biological characteristics

South Africa The coelacanth is a lobe-finned fish with the pectoral and anal fins on fleshy stalks supported by bones, and the tail fin divided into three lobes, the middle one of which also has a stalk. The coelacanth has modified cosmoid scales, which are thinner than true cosmoid scales, which can only be found on extinct fish. Coelacanths were believed to first appear in the Carboniferous Period, about 400-350 million years ago. The coelacanth, which is closely related to lungfishes, used to live in many bodies of water in prehistoric times. The average weight of the coelacanth is 176 pounds (80 kg) and they can reach up to 6.5 feet (2 m) in length. They are the only living species known to have a functional intercranial joint, a type of hinge that aids in the consumption of large prey. Coelacanths are also mucilaginous; their scales release mucus and their bodies continually exude oil. This oil is a laxative, and makes the fish almost inedible unless dried and salted.

Morphology of the coelacanth skeleton

laxative View 3D computed tomographic (CT) imagery of the coelacanth skeleton, including labeled images of the intracranial joint, at [http://digimorph.org/specimens/Latimeria_chalumnae/whole/ Digimorph.org]

Discovery

First find in South Africa

laxative The first hint that western scientists had of a modern, living coelacanth existed was when Marjorie Courtenay-Latimer, who was curator of a museum in East London, South Africa, was inspecting local fish catches for unusual specimens in 1938. She was looking at the catch of a fishing boat that had been fishing for sharks near the Chalumna River and saw an odd blue fish fin in the catch. She pulled the fish out of the pile and brought it to the museum to find out what kind of fish it was. Failing to find it in any of her books, she attempted to contact her friend, Professor James Leonard Brierley Smith, but he was away. Unable to preserve the fish, she sent it to a taxidermist. When Smith returned, he immediately recognized it as a coelacanth, known only from fossils. The species was named Latimeria chalumnae in honour of her and the waters in which it was found. The fish was referred to as a "Living Fossil".

Comoros

A worldwide search was launched for more coelacanths, with a reward of 100 British pounds (a very substantial sum to the average South African fisherman of the time). Fourteen years later, they were found in the Comoros, at first only another single specimen, but later it turned out that the fish was no stranger to local knowledge: the Comorians, in the port of Mutsamudu on the Comorian island of Anjouan, were puzzled that someone would pay big money for what the locals called a gombessa or mame, an inferior (nearly inedible) fish that their fishermen occasionally caught by mistake. They now understand the significance of their endangered species and have a program in place to return any accidentally caught gombessa to deep water so that they can survive. The second specimen, found in 1952 by Comorian fisherman Ahmed Hussain, was originally described as a different species, Malania anjounae (after Daniel François Malan), but it turned out that the lack of the first dorsal fin, which was believed to distinguish it from Latimeria, was due to an injury early in the animal's life. Ironically, Malan was a staunch creationist; on seeing the supposed ancestor of all terrestrial life named after him, his reaction was a startled, "Why it's ugly! Is this where we come from?" Smith, who died in 1968, wrote his account of the coelacanth story in the book Old Fourlegs, first published in 1956. His book Sea Fishes of the Indian Ocean, illustrated and co-authored by his wife Margaret, remains the standard ichthyological reference for the region.

Second species in Indonesia

In 1997, Arnaz and Mark Erdmann were traveling on honeymoon in Indonesia and saw a strange fish entering the market at Manado Tua, on the island of Sulawesi. Arnaz Erdmann recognized it as a gombessa, but it was brown, not blue. (The Erdmanns did not realize this was a new species until an expert saw their photo on the web.) DNA testing revealed that this species, called rajah laut ('King of the Sea') by the Indonesians, is not related to the Comorian population. It was given the scientific name Latimeria menadoensis.

St. Lucia Marine Protected Area in South Africa

In South Africa, the search continued on and off over the years. One diver, 46-year-old Riaan Bouwer, lost his life exploring for coelacanths in June 1998. On October 28th, 2000, just south of the Mozambique border, in Sodwana Bay in the St. Lucia Marine Protected Area, three deep-water divers - Pieter Venter, Peter Timm and Etienne le Roux - made a dive to 104 metres and suddenly spotted a coelacanth. However, they were diving without cameras. The group vowed to return with photographic equipment. Calling themselves SA Coelacanth Expedition 2000, the group returned, this time with several additional members. On November 26 they performed a first dive, but did not witness any coelacanths. The next day, four members of the group - Pieter Venter, Gilbert Gunn, Christo Serfontein and Dennis Harding - went down again. Moving from cavern to cavern, they found three coelacanths. The largest was between 1.5 and 1.8 metres long, the other two 1.2 metres and 1 metre. The fish swam heads down and appeared to be feeding off of ledges. The cameramen took video footage and photos. Then, however, disaster struck. Christo suddenly passed out under water, and 34-year-old Dennis Harding rose to the surface with him in an uncontrolled ascent. Harding complained of neck pains and died in the boat. Apparently, he had suffered a cerebral embolism. Christo recovered after being taken underwater for recompression. However, the find was big news in South Africa. In March-April 2002, the Jago Submersible and Fricke Dive Team descended into the depths off Sodwana and observed 15 coelacanths, one pregnant. Tissue samples were taken using a dart probe.

Taxonomic notes

Coelacanthimorpha or Actinistia are sometimes used to designate the group of Sarcopterygian fishes that contains the Coelacanthiformes.

References


- "Marjorie Courtenay-Latimer." The Daily Telegraph (London). May 19, 2004.
- Myrna Oliver. "Marjorie Courtenay-Latimer, 97; Confirmed Rare Fish's Existence." Los Angeles Times. June 13, 2004. pg. B.16
- Jeremy Pearce. "Marjorie Courtenay-Latimer, Naturalist, Is Dead at 97." New York Times. June 7, 2004. pg. B.6
- Keith S. Thompson. Living Fossil: The Story of the Coelacanth. New York: W.W. Norton, 1991.

See also


- Living fossil

External links


- [http://www.acep.co.za/ African Coelacanth Ecosystem Programme], ACEP, as the South African Coelacanth Conservation and Genome Resource Programme
- [http://thestar.com.my/lifestyle/story.asp?file=/2004/8/17/features/8593109&s Living fossil fish in Indonesian waters], article at The Star Online (needs subscription)
- [http://marinebio.org/species.asp?id=54 Coelacanth] at MarineBio.org
- [http://www.cnn.com/TECH/science/9809/23/living.fossil CNN: Coelacanth]
- [http://news.bbc.co.uk/1/hi/sci/tech/1331848.stm BBC: Coelacanth]
- [http://www.pbs.org/wgbh/nova/fish/ PBS: NOVA - Ancient Creature of the Deep] Category:Lobe-finned fish Category:Living fossils ja:シーラカンス JeLiSa

Dipnoi

:For the musical band, see Lungfish (band).
see text Lungfishes are sarcopterygian fish that can breathe air (and in some species are obligate air-breathers), and have limb-like appendages instead of fins. There are six living species known; four in Africa, and one each in South America and Australia. Most of their skeleton is made out of cartilage, and electro receptors can be seen as tiny holes under their jaw. The modern lungfishes have a number of larval features, which suggest paedomorphosis. They have probably the largest genome among the vertebrates. They all have an elongate body, four limbs, and a single rear fin.

Taxonomy

Taxonomy of lungfishes presents some difficulty because of their resemblances to both fish and land-dwelling vertebrates, and have been classified in a variety of ways, ranging from class Dipnoi, to infraclass Dipnomorpha, to order Dipteriformes. However, there is general agreement that there are two main subcategories, here given as orders:
- Ceratodontiformes: characterized by having broad flipper-like fins and an unpaired lung.
  - Family Ceratodontidae,
    - Genus Neoceratodus
      - Neoceratodus forsteri - Queensland Lungfish
- Lepidosireniformes: characterized by having thread-like fins and paired lungs.
  - Family Lepidosirenidae
    - Genus Lepidosiren
      - Lepidosiren paradoxa - South American Lungfish
  - Family Protopteridae
    - Genus Protopterus
      - Protopterus aethiopicus - Marbled Lungfish
      - Protopterus amphibius - East African Lungfish
      - Protopterus annectens - African Lungfish
      - Protopterus dolloi - Slender Lungfish

External links


- [http://www.lungfish.info Lungfish information site] Category:Chordates Category:Lungfish

Lungfish

:For the musical band, see Lungfish (band).
see text Lungfishes are sarcopterygian fish that can breathe air (and in some species are obligate air-breathers), and have limb-like appendages instead of fins. There are six living species known; four in Africa, and one each in South America and Australia. Most of their skeleton is made out of cartilage, and electro receptors can be seen as tiny holes under their jaw. The modern lungfishes have a number of larval features, which suggest paedomorphosis. They have probably the largest genome among the vertebrates. They all have an elongate body, four limbs, and a single rear fin.

Taxonomy

Taxonomy of lungfishes presents some difficulty because of their resemblances to both fish and land-dwelling vertebrates, and have been classified in a variety of ways, ranging from class Dipnoi, to infraclass Dipnomorpha, to order Dipteriformes. However, there is general agreement that there are two main subcategories, here given as orders:
- Ceratodontiformes: characterized by having broad flipper-like fins and an unpaired lung.
  - Family Ceratodontidae,
    - Genus Neoceratodus
      - Neoceratodus forsteri - Queensland Lungfish
- Lepidosireniformes: characterized by having thread-like fins and paired lungs.
  - Family Lepidosirenidae
    - Genus Lepidosiren
      - Lepidosiren paradoxa - South American Lungfish
  - Family Protopteridae
    - Genus Protopterus
      - Protopterus aethiopicus - Marbled Lungfish
      - Protopterus amphibius - East African Lungfish
      - Protopterus annectens - African Lungfish
      - Protopterus dolloi - Slender Lungfish

External links


- [http://www.lungfish.info Lungfish information site] Category:Chordates Category:Lungfish

Tetrapod

:Amphibia
Elginerpetontidae
Acanthostegidae
Ichthyostegidae
:Whatcheeriidae
:Crassigyrinidae
:Baphetidae
:Colosteidae
:(Batrachomorpha)
:Temnospondyli
:Lepospondyli
:Reptiliomorpha
::Amniota
:::Sauropsida/Reptilia
::::Aves (Birds)
:::Synapsida
::::Mammalia Tetrapods (Greek tetrapoda, "four-legged") are the most successful body form; a vertebrate animal having four feet, legs or leglike appendages. Since amphibians, reptiles, dinosaurs and mammals are all tetrapods, and even birds and snakes are tetrapods by descent, the term is only really useful in describing the earliest tetrapods, which radiated from the Sarcopterygii, or "lobe-finned" fishes, into air-breathing amphibians in the Devonian period. The Latin version of "tetrapod" is "quadruped," meaning any four-legged creature.

Devonian Tetrapods

The first tetrapods evolved in shallow and swampy freshwater habitats, towards the end of the Devonian, a little more than 360 million years ago. By the late Devonian, land plants had stabilized freshwater habitats, allowing the first wetland ecosystems to develop, with increasingly complex food webs that afforded new opportunities. Primitive tetrapods developed from a lobe-finned fish (an "osteolepid Sarcopterygian"), with a two-lobed brain in a flattened skull, a wide mouth and a short snout, whose upward-facing eyes show that it was a bottom-dweller, and which had already developed adaptations of fins with fleshy bases and bones. The "living fossil" coelacanth is a related lobe-finned fish without these shallow-water adaptations. These fishes used their fins as paddles in shallow-water habitats choked with plants and detritus. The universal tetrapod characteristics of front limbs that bend backward at the elbow and hind limbs that bend forward at the knee can plausibly be traced to early tetrapods living in shallow water. The evolution of the air-breathing lung from the primitive swim bladder of lobe-finned fishes has not yet been worked out in detail. However, functioning internal gills were present in at least one late Devonian tetrapod, Acanthostega. Nine genera of Devonian tetrapods have been described, several known mainly or entirely from lower jaw material. All of them were from the European-North American supercontinent that comprised Europe, North America and Greenland. The only exception is a single Gondwanan genus, Metaxygnathus, which has been found in Australia. The first Devonian tetrapod identified from Asia was recognized from a fossil jawbone reported in 2002. The Chinese tetrapod Sinostega pani was discovered among fossilized tropical plants and lobe-finned fish in the red sandstone sediments of the Ningxia Hui Autonomous Region of northwest China. This finding substantially extended the geographical range of these animals and has raised new questions about the worldwide distribution and great taxonomic diversity they achieved within a relatively short time. These earliest tetrapods were not terrestrial. The earliest confirmed terrestrial forms are known from the early Carboniferous deposits, some 20 million years later. Still, they may have spent very brief periods out of water and would have used their legs to paw their way through the mud.
- [http://www.palaeos.com/Vertebrates/Units/140Sarcopterygii/140.800.html#Osteolepiformes Cladistic analysis of osteolepiform Sarcopterygians]

Carboniferous Tetrapods

Until the 1990s, there was a 30-million year gap in the fossil record between the late Devonian tetrapods and the reappearance of tetrapod fossils in recognizable mid-Carboniferous amphibian lineages. It was referred to as "Romer's Gap", after the palaeontologist who recognized it. During the "gap", tetrapod backbones developed, as did limbs with digits and other adaptations for terrestrial life. Ears, skulls and vertebral columns all underwent changes too. The number of digits on hands and feet became standardized at five, as lineages with more digits died out. The very few tetrapod fossils found in the "gap" are all the more precious. The transition from an aquatic lobe-finned fish to an air-breathing amphibian was a momentous occasion in the evolutionary history of the vertebrates. For an animal to live in a gravity-neutral, aqueous environment and then invade one that is entirely different required major changes to the overall body plan, both in form and in function. Eryops is an example of an animal that made such adaptations. It retained and refined most of the traits found in its fish ancestors. Sturdy limbs supported and transported its body while out of water. A thicker, stronger backbone prevented its body from sagging under its own weight. Also, by utilizing vestigial fish jaw bones, a rudimentary ear was developed, allowing Eryops to hear airborne sound. By the Visean age of mid-Carboniferous times the early tetrapods had radiated into three main branches. Recognizable basal-group Amphibia (frogs, salamanders and caecilians) are representative of the labyrinthodonts, which are comprised of the temnospondyls (e.g. Eryops) and similarly primitive Amniota that now include mammals, turtles, crocodiles, birds, lizards and snakes, represented in mid-Carboniferous times by the anthracosaurs. As living members of the tetrapod clan—that is of the tetrapod "crown-group"—these varied tetrapods represent the phylogenetic end-points of these two divergent lineages. A third Palaeozoic group, the baphetids, left no modern survivors.

Permian Tetrapods

In the Permian period, as the separate tetrapod lineages each developed in their own way, the term "tetrapoda" becomes less useful. Each lineage, however, remains grouped with the tetrapoda, just as Homo sapiens could be considered a very highly-specialized kind of lobe-finned fish. Most tetrapods today are terrestrial, at least in their adult forms, but some species, such as the axolotl, remain aquatic. Tetrapods that returned to the sea include ichthyosaurs and modern whales and dolphins.

Classification of Tetrapods

There are four main categories of living ("crown group") tetrapods: ;Amphibia : frogs and toads, newts and salamanders ;Anapsida : only extant examples are turtles ;Synapsida : many extinct species and all mammals ;Diapsida : dinosaurs, most modern reptiles, and birds Note that snakes are considered tetrapods because they are descended from ancestors who had a full complement of limbs. Similar considerations apply to aquatic mammals.

Anatomical features of early tetrapods

The amphibian's ancestral fish must have possessed similar traits to those inherited by the early amphibians, including internal nostrils (to separate the breathing and feeding passages) and a large fleshy fin built on bones that could give rise to the tetrapod limb. The rhipidistian crossopterygians fulfill every requirement for this ancestry. Their palatal and jaw structures were identical to those of amphibians, and their dentition was identical too, with labyrinthine teeth fitting in a pit-and-tooth arrangement on the palate. The crossopterygian paired fins were smaller than tetrapod limbs, but the skeletal structure was very similar in that the crossopterygian had a single proximal bone (analogous to the humerus or femur), two bones in the next segment (forearm or lower leg), and an irregular subdivision of the fin, roughly comparable to the structure of the carpus / tarsus and phalanges of a hand. The major difference between crossopterygians and amphibians was in relative development of front and back skull portions; the snout is much less developed than in most amphibians and the post-orbital skull is exceptionally longer than an amphibian's. A great many kinds of early amphibians lived during the Carboniferous period. Therefore, their ancestor would have lived earlier, during the Devonian period. Devonian Ichthyostegids were the earliest of amphibians, with a skeleton that is directly comparable to that of rhipidistian ancestors. Early Labyrinthodonts (Late Devonian to Early Mississippian) still had some ichthyostegid features such as similar skull bone patterns, labyrinthine tooth structure, the fish skull-hinge, pieces of gill structure between the cheek and shoulder, and the vertebral column. They had, however, lost several other fish features such as the fin rays in the tail. In order to propagate in the terrestrial environment, certain challenges had to be overcome. The animal's body needed additional support, because buoyancy was no longer a factor. A new method of respiration was required in order to extract atmospheric oxygen, instead of oxygen dissolved in water. A means of locomotion would need to be developed to traverse distances between waterholes. Water retention was now important since it was no longer the living matrix, and it could be lost easily to the environment. Finally, new sensory input systems were required if the animal was to have any ability to function reasonably while on land.

Classification

Labyrinthodontia Diagnostic features unique to the Labyrinthodontia are hard to find at first glance; the complex dentine infolding tooth structure was shared with crossopterygian fish. The labyrinthodonts are divided into the Temnospondyli and the Anthracosauria, the main difference between the two groups being their respective vertebral structures. The Anthracosauria had small pleurocentra, which grew and fused, becoming the true centrum in later vertebrates. In contrast, the Temnospondyli had a conservative vertebral column in which the pleurocentra remained small in primitive forms, vanishing entirely in the more advanced ones. The intercentra are large and form a complete ring. Temnospondyls A diagnostic feature of the Temnospondyli was that the tabular bone in the skull roof is relatively small and had no contact with the parietal bone, whereas contact between the two bones was present in all anthracosaurs. Although the temnospondyls flourished in many forms in the Late Palaeozoic and Triassic, they were an entirely self-contained group and did not give rise to any later tetrapod groups. It was the sister group Anthracosauria that gave rise to the reptiles. Within the Temnospondyli are the two suborders Rachitomi and Stereospondyli, also distinguished by their vertebrae. There were three distinct successive stages within the Rachitomi, the first occurring in the Carboniferous. The second happened mostly in the Pennsylvanian, continuing into Permian, of which Erydops is characteristic. The third and final stage was in the Late Carboniferous and Early Permian, from which Eryops of the Texas Permian red beds is best known. Just as there were numerous side branches throughout the evolution of the temnospondyls, so too were there many of the rachitomes. Of special interest in regard to the Rachitomi, is Branchiosaurus. This relatively tiny amphibian lived from the Late Pennsylvanian to the Early Permian and was very similar to the Rachitomi, differing only in its small size. However, it had a much less ossified skeleton, a short skull and other distinguishing features. Clear traces of gills are present in many fossilized samples, hence the name. Thought to have vertebra differing from rachitomous vertebrae, it was placed in a separate order named Phyllospondyli. Only later was it realized, by studying growth stages and seeing increasing ossification in larger specimens, that it was in fact the larval stage of a much larger rachitome like Eryops.

Skull

The most notable characteristic that makes an amphibian skull different from a fishes' are the relative frontal and rear portion lengths. The fish had a long rear portion while the front was short; the orbital vacuities were thus located towards the anterior end. In the amphibian, the front of the skull lengthened, positioning the orbits farther back on the skull. The lacrimal bone was not