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Gars are members of the Lepisosteiformes (or Semionotiformes), an ancient holosteian order of ray-finned fish; fossils from this order are known from the Late Jurassic onwards. The family Lepisosteidae includes seven living species of fish in two genera that inhabit fresh, brackish, and occasionally marine, waters of eastern North America, Central America and the Caribbean islands.[2][3] Gars have elongated bodies that are heavily armored with ganoid scales,[4] and fronted by similarly elongated jaws filled with long, sharp teeth. Gars are sometimes referred to as "garpike" but they are not related to pike which are in the Esocidae family of fishes. All of the gars are relatively large fish, but the alligator gar (Atractosteus spatula) is the largest, as specimens have been reported to be 3 m (9.8 ft) in length;[5] however, they typically grow to 2 m (6.5 ft) and weigh over 45 kg (100 lb).[6] Unusually, their vascularised swim bladders can function as lungs,[7] and most gars surface periodically to take a gulp of air. Gar flesh is edible and the hard skin and scales of gars are used by humans; however their eggs are highly toxic.

Gar
Temporal range: Kimmeridgian–Recent[1]
Lepisosteus oculatus.jpg
Spotted gar
(Lepisosteus oculatus)
Scientific classification
Kingdom:
Phylum:
Class:
Subclass:
Infraclass:
Order:
O. P. Hay, 1929
Family:
G. Cuvier, 1825
Genera

Contents

EtymologyEdit

The name gar was originally used for a species of needlefish (Belone belone) found in the North Atlantic and likely taking its name from the Old English word for "spear".[8] Belone belone is now more commonly referred to as the "garfish" or "gar fish" to avoid confusion with the North American gars of the family Lepisosteidae.[9] Confusingly, the name "garfish" is commonly used for a number of other species of the related genera Strongylura, Tylosurus and Xenentodon of the family Belonidae.

The genus name Lepisosteus comes from the Greek lepis meaning "scale" and osteon meaning "bone".[10] Atractosteus is similarly derived from Greek, in this case from atraktos, meaning arrow.[11]

DistributionEdit

Fossil gars are found in Europe, India, South America, and North America, indicating that in times past, these fish had a wider distribution than they do today. Gars are considered to be a remnant of a group of bony fish that flourished in the Mesozoic, and are most closely related to the bowfin. The distribution of the Gar Lepisosteidae in North America, lies mainly in the shallow, brackish waters off of Texas and Louisiana, and off the eastern coast of Mexico.[12][13] A few populations are also present in the Great Lakes region of the United States, living in similar shallow waters.[14]

AnatomyEdit

 
Large gar in an aquarium

ScalesEdit

 
Atractosteus fossil

Gar bodies are elongated, heavily armored with ganoid scales, and fronted by similarly elongated jaws filled with long, sharp teeth. Their tails are heterocercal, and the dorsal fins are close to the tail.[15]

Swim bladderEdit

As their vascularised swim bladders can function as lungs,[7] most gars surface periodically to take a gulp of air, doing so more frequently in stagnant or warm water when the concentration of oxygen in the water is low. Experiments on the swim bladder has shown that the temperature of the water affects which respiration method the gar will use: aerial or aquatic. They will increase the aerial breathing rate (breathing air) as temperature of the water is increased. Gars can live completely submerged in oxygenated water without access to air and remain healthy while also being able to survive in deoxygenated water if allowed access to air.[16] This adaptation can be the result of environmental pressures and behavioral factors.[17] As a result of this organ, they are extremely resilient and able to tolerate conditions that most other fish could not survive in.

Pectoral girdleEdit

 
Medial and lateral view of Lepisosteidae pectoral girdle

The gar has paired appendages, including pectoral fins, pelvic fins, while also having an anal fin, caudal fin, and a dorsal fin.[18] The bone structures within the fins are important to study as they can show homology throughout the fossil record. Specifically, the pelvic girdle resembles that of other actinopterygians yet still having some of its own characteristics. Gars have a postcleithrun - which is a bone that is lateral to the scapula, but do not have postpectorals. Proximally to the postcleithrum, the supracleithrum is important as it plays a critical role in opening the gar's jaws. This structure has a unique internal coracoid lamina only present in the Gar species. Proximal to the supracleithrum is the posttemporal bone, which is significantly smaller than other actinopterygians. Gars also have no clavicle bone, although there have been observations of elongated plates within the area.[19]

MorphologyEdit

 
Fin chart for shortnose gar

All the gars are relatively large fish, but the alligator gar Atractosteus spatula is the largest. The largest alligator gar ever caught and officially recorded was 8 ft 5 14 in (2.572 m) long, weighed 327 lb (148 kg), and was 47 in (120 cm) around the girth.[20] Even the smaller species, such as Lepisosteus oculatus, are large, commonly reaching lengths of over 60 cm (2.0 ft), and sometimes much more.[21]

EcologyEdit

 
A range map of Lepisosteiformes.

Gars tend to be slow-moving fish except when striking at their prey. They prefer the shallow and weedy areas of rivers, lakes, and bayous, often congregating in small groups.[2] They are voracious predators, catching their prey with their needle-like teeth, obtained with a sideways strike of the head.[21] They feed extensively on smaller fish and invertebrates such as crabs.[5] Gars are found across much of North America (for example Lepisosteus osseus).[2] Although gars are primarily found in freshwater habitats, several species enter brackish waters and a few, most notably Atractosteus tristoechus, are sometimes found in the sea. Some gars travel from lakes and rivers through sewers to get to ponds.[2][22]

Species and IdentificationEdit

The gar family contains seven extant species, in two genera:[7]

Cladogram of living gars[23]
Lepisosteidae
Atractosteus

A. tropicus

A. tristoechus

A. spatula

Lepisosteus

L. oculatus

L. platyrhincus

L. osseus

L. platostomus

Family Lepisosteidae

Alligator garEdit

The largest member of the gar family, the alligator gar (Atractosteus spatula). The ancient fish reaches the length of up to 10 feet, and over 300 pounds.[25][26]The alligator gar's body and snout is wide and stocky. It's name was formed when locals confused this animal for an alligator.[25][27] This large species can be found in Texas, Oklahoma, Mississippi River, Ohio, Missouri river, and the southern drainages into Mexico.[27][26]Their habitat consists of lakes and bays where slow currents run through.[26] As young, the gar grows rapidly in size. Once the alligator gar is an adult, its growth is slower in pace.[28] Coloration of this type is all deep green or yellow.[27][26] Recreational fishing of the alligator gar became popular due to its massive size, and sold for its meat in local areas.[29]After over 5 decades this event caused almost extinction of the species.[27][28]Man made dams have contributed to this loss by the gar not being able to spawn in flood plain areas.[29]Laws have been put in place to reduce the overfishing and conservation program efforts to reintroduce the alligator gar to regain number count. [27][28]Before being released into selected water locations, each gar has to be measured and meet a certain length requirement for the best chance of survival rate.[30]In states such as Texas, there's a limitation of how many gar can be caught in a day, a season on when to fish them, equipment allowed to be used, and length restrictions.[31]Scientists have found that the alligator gar can help maintain the ecosystem balance by showing scientists where positive reproduction habitats can be found, as well as for other migratory species.[32]

 
Alligator Gar (Atractosteus spatula)

Florida garEdit

Florida gar (Lepisosteus platyrhincus) can be found in the Ocklockonee river, Florida, and Georgia.[33][34] Sticking to preferred locations of mud or sandy bottoms, with bountiful vegetation.[33][35]Florida gar are commonly confused with its cousin, the spotted gar.[33] They have uneven black spots covering the head, body, and fins.[33][34] Coloration of green-brown scales along the back of the body, and white or yellow on the underbelly.[33][36] This close coloration to its habitat, allows this predator to ambush its pray.[33][36] The Florida gar doesn't have ganoid scales located on the throat.[33] Female Florida gar grow bigger than its counterpart, of sizes between 13-34 inches.[33][36]

Spotted garEdit

The spotted gar (Lepisosteus oculatus) is a smaller gar specie.[37] Just under 4 feet and average of 15 pounds.[37] Females, are larger than the male spotted gar.[38]This gar has dark spots covering its head, body, and fins.[37]Their bodies are compact, and have shorter snouts.[37]They prefer to live in more clear shallow waters between 3-5 meters deep.[39] Surrounding itself in brush foliage.[38] [40]Located in the waters of Lake Michigan, Lake Erie Basin, Mississippi River System, and river drainages along the northern coast of the Gulf of Mexico from the Nueces River in Texas east to the lower Apalachicola River in Florida.[38][41] Sharing common waters with the alligator gar. the alligator gar is the main predator of spotted gar. These smaller gar live at a lifespan average of 18 years.[38]A new discovery has been found by scientists, that spotted gar genetics can create new found understandings of human development and diseases.[39]It's also been found that these gar show where best spawning for other recreational fishes are located.[41]

 
Spotted Gar (Lepisosteus oculatus)

Shortnose garEdit

The shortnose gar (Lepisosteus platostomus), located in the Mississippi River Basin, Indiana,Wisconsin, Montana, Alabama, and Louisiana.[42] Living in habitats of lakes, swamps, and calm pools.[43][42] Relative to other gar species, the shortnose gar is characterized by its shorter and broad snout.[42][44]Like the longnose gar, it has one row of teeth. The upper jaw is longer than the rest of its head.[42] The coloration of the shortnose gar is similar to the alligator gar, a deep green or a brown color.[42] [44]Depending on the clarity of water, spots can be present on the caudal, dorsal, and anal fins.[42] They have a lifespan of 20 years and reaches up to 5 pounds in weight.[45] The shortnose gar grows to lengths of 24-35 inches.[45][46] This species of gar consumes more invertebrates than any other gars.[42]A high content of Asian carp fish has been discovered in shortnose gar stomachs than any other native species of fish.[47]

Longnose GarEdit

The Longnose gar (Lepisosteus osseus), like its name, has a longer and more narrow cylindrical body.[48][49]The longnose gar's snout is more than twice the length of the rest of its head, distinguishing it from other gar relatives.[50] [51]Reaching 6 feet and 8 inches in length and weighing up to 35-80 pounds.[48][50] Unlike the alligator gar, the longnose gar only has a single row of teeth.[50][52]Unlike its relatives, they enter brackish water from time to time.[50] [53]Females are larger and live longer than the male longnose gar.[50] [49]Females living 22 years, and males about half as long.[50] There are spots on the head, dorsal, anal, and caudal fins.[50][48][54] Depending on the water clarity, the longnose gar comes in two colors.[50] In clear water, they're a dark deep green color. In muddy waters, it's more brown in color.[50] Edges of the ganoid scales and in between are black.[50][54] These type of gar are occasionally fished by locals, and blamed for eating other fish in the rivers.[50][49] The longnose gar has a large range of territory in North America, into the Gulf of Mexico.[50] [54]Located in Florida, Quebec, all Great Lakes except Lake Superior, Missouri, Mississippi, Texas, and northern Mexico.[50][55]

 
Longnose Gar (Lepisosteus osseus)

RoeEdit

 
Lepisosteus platyrhincus

Gar flesh is edible, and sometimes available in markets, but unlike the sturgeon they resemble, their eggs are highly toxic to humans.[56] Gar eggs are toxic because of a protein toxin called ichthyotoxin.[57] The protein can be denatured when brought to a temperature of 120 degrees celsius.[58] When cooking roe, the temperature does not typically get that high so the protein stays intact and causes severe symptoms. It was once thought that the production of the toxin in gar roe was an evolutionary adaptation to provide protection for the eggs. However, bluegills and channel catfish were fed gar eggs and remained healthy, even though they are the natural predators of the gar eggs. Crayfish were not immune to the toxin and most of the crayfish that ate the roe died. It may just be a coincidence that the roe is toxic to humans and crayfish.[57]

Significance to humansEdit

Several species are traded as aquarium fish.[21] The hard skin and scales of the gar were used by humans. Native Americans used the scales of the gar as arrowheads, native Caribbeans used the skin for breastplates, and early American pioneers covered the blades of their plows in gar skin.[59] Not much is known about the precise function of the gar in Native American religion and culture, but besides using the gar, Creek and Chickasaw people have ritual "garfish dances".[60]

 
A gar leaps out of the water.

ReferencesEdit

  1. ^ a b Paulo M. Brito; Jésus Alvarado-Ortega; François J. Meunier (2017). "Earliest known lepisosteoid extends the range of anatomically modern gars to the Late Jurassic". Scientific Reports. 7 (1): Article number 17830. Bibcode:2017NatSR...717830B. doi:10.1038/s41598-017-17984-w. PMC 5736718. PMID 29259200.
  2. ^ a b c d "Family Lepisosteidae - Gars". Retrieved 2007-04-21.
  3. ^ Sterba, G: Freshwater Fishes of the World, p. 609, Vista Books, 1962
  4. ^ Sherman, Vincent R.; Yaraghi, Nicholas A.; Kisailus, David; Meyers, Marc A. (2016-12-01). "Microstructural and geometric influences in the protective scales of Atractosteus spatula". Journal of the Royal Society Interface. 13 (125): 20160595. doi:10.1098/rsif.2016.0595. ISSN 1742-5689. PMC 5221522. PMID 27974575.
  5. ^ a b "Atractosteus spatula - Alligator gar". Retrieved 2007-07-19.
  6. ^ "Atractosteus spatula". Florida Museum of Natural History. Retrieved 2016-04-21.
  7. ^ a b c Froese, Rainer, and Daniel Pauly, eds. (2009). "Lepisosteidae" in FishBase. January 2009 version.
  8. ^ "Gar". Retrieved 2007-04-21.
  9. ^ "Common Names of Belone belone". Archived from the original on 2007-10-19. Retrieved 2007-04-21.
  10. ^ "Genera reference detail". Retrieved 2007-04-21.
  11. ^ "Genera reference detail". Retrieved 2016-02-21.
  12. ^ "Atractosteus spatula :: Florida Museum of Natural History". www.floridamuseum.ufl.edu. 2017-05-10. Retrieved 2018-05-11.
  13. ^ "Lepisosteus oculatus (Spotted gar)". Animal Diversity Web. Retrieved 2018-05-11.
  14. ^ "Spotted Gar (Lepisosteus oculatus) - Species Profile". nas.er.usgs.gov. Retrieved 2018-05-11.
  15. ^ Wiley, Edward G. (1998). Paxton, J.R.; Eschmeyer, W.N. (eds.). Encyclopedia of Fishes. San Diego: Academic Press. pp. 78–79. ISBN 0-12-547665-5.
  16. ^ Renfro, Larry; Hill, Loren (1970). "Factors Influencing the Aerial Breathing and Metabolism of Gars (Lepisosteus)". The Southwestern Naturalist. 15 (1): 45–54. doi:10.2307/3670201. JSTOR 3670201.
  17. ^ Hill, Loren (1972). "Social Aspects of Aerial Respiration of Young Gars (Lepisosteus)". The Southwestern Naturalist. 16 (3): 239–247. doi:10.2307/3670060. JSTOR 3670060.
  18. ^ Becker, George (1983). "Fishes of Wisconsin" (PDF): 239–248.
  19. ^ Malcolm, Jollie (1984). "Development of Cranial and Pectoral Girdle Bones of Lepisosteus with a Note on Scales". Copeia. American Society of Ichthyologists and Herpetologists (ASIH). 1984 (2): 476–502. doi:10.2307/1445204. JSTOR 1445204.
  20. ^ "Alligator Gar (Atractosteus spatula)". Texas Parks & Wildlife Department. Retrieved March 8, 2016.
  21. ^ a b c Kodera H. et al.: Jurassic Fishes. TFH, 1994, ISBN 0-7938-0086-2[page needed]
  22. ^ Monks N. (editor): Brackish Water Fishes, pp 322–324. TFH 2006, ISBN 0-7938-0564-3
  23. ^ Jeremy J. Wright, Solomon R. David, Thomas J. Near: Gene trees, species trees, and morphology converge on a similar phylogeny of living gars (Actinopterygii: Holostei: Lepisosteidae), an ancient clade of ray-finned fishes. Molecular Phylogenetics and Evolution 63 (2012) 848–856 PDF
  24. ^ Cavin, Lionel; Martin, Michel; Valentin, Xavier (1996). "Occurrence of Atractosteus africanus (actinopterygii, lepisosteidae) in the early Campanien of Ventabren (Bouches-du-Rhône, France). Paleobiogeographical implications". Revue de Paléobiologie. 15 (1): 1–7.
  25. ^ a b "How to Identify Alligator Gar". tpwd.texas.gov. Retrieved 2019-07-20.
  26. ^ a b c d "Atractosteus spatula summary page". FishBase. Retrieved 2019-07-26.
  27. ^ a b c d e "Alligator Gars, Alligator Gar Pictures, Alligator Gar Facts". National Geographic. 2009-12-15. Retrieved 2019-07-24.
  28. ^ a b c "Alligator Gar (Atractosteus spatula)". tpwd.texas.gov. Retrieved 2019-07-26.
  29. ^ a b "Alligator Gar". U.S. Fish and Wildlife Service.
  30. ^ "Fishing in Illinois". www.ifishillinois.org. Retrieved 2019-08-03.
  31. ^ "Who Fishes for Alligator Gar?". tpwd.texas.gov. Retrieved 2019-08-03.
  32. ^ "Conservation of Ancient Fishes: Reintroducing the Alligator Gar; and What About Those Carp?". National Geographic Society Newsroom. 2016-08-08. Retrieved 2019-08-03.
  33. ^ a b c d e f g h "Lepisosteus platyrhincus". Florida Museum. 2017-05-10. Retrieved 2019-07-24.
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  35. ^ "FAMILY Details for Lepisosteidae - Gars". www.fishbase.in. Retrieved 2019-07-26.
  36. ^ a b c "Toronto Zoo | Florida gar". www.torontozoo.com. Retrieved 2019-08-03.
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  38. ^ a b c d Givinsky, Lana Hall; Thomas Meade; Drew Paulette; Josh Albert; Stephanie. "Lepisosteus oculatus (Spotted gar)". Animal Diversity Web. Retrieved 2019-07-24.
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  42. ^ a b c d e f g Bradburn, Mark. "Lepisosteus platostomus (Shortnose gar)". Animal Diversity Web. Retrieved 2019-07-24.
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  45. ^ a b "Lepisosteus platostomus summary page". FishBase. Retrieved 2019-07-24.
  46. ^ "Spotted Gar (Lepisosteus oculatus) - Species Profile". nas.er.usgs.gov. Retrieved 2019-07-26.
  47. ^ "Conservation of Ancient Fishes: Reintroducing the Alligator Gar; and What About Those Carp?". National Geographic Society Newsroom. 2016-08-08. Retrieved 2019-08-03.
  48. ^ a b c "How to Identify Alligator Gar". tpwd.texas.gov. Retrieved 2019-07-20.
  49. ^ a b c "Longnose Gar | Chesapeake Bay Program". www.chesapeakebay.net. Retrieved 2019-07-26.
  50. ^ a b c d e f g h i j k l m "Lepisosteus osseus". Florida Museum. 2017-05-10. Retrieved 2019-07-24.
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  52. ^ "Gar - NYS Dept. of Environmental Conservation". www.dec.ny.gov. Retrieved 2019-08-03.
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  54. ^ a b c "National Aquarium | Longnose Gar". National Aquarium. Retrieved 2019-08-03.
  55. ^ "Longnose Gar". MDC Discover Nature. Retrieved 2019-08-03.
  56. ^ "Gar". Environment.nationalgeographic.com. Retrieved 29 May 2011.
  57. ^ a b Ostrand, Kenneth G.; Thies, Monte L.; Hall, Darrell D.; Carpenter, Mark (1996). "Gar ichthyootoxin: Its effect on natural predators and the toxin's evolutionary function". The Southwestern Naturalist. 41 (4): 375–377. JSTOR 30055193.
  58. ^ Fuhrman, Frederick A.; Fuhrman, Geraldine J.; Dull, David L.; Mosher, Harry S. (1969-05-01). "Toxins from eggs of fishes and amphibia". Journal of Agricultural and Food Chemistry. 17 (3): 417–424. doi:10.1021/jf60163a043. ISSN 0021-8561.
  59. ^ Burton, Maurice; Robert Burton (2002). The international wildlife encyclopedia, Volume 9. Marshall Cavendish. p. 929. ISBN 978-0-7614-7266-7. Retrieved 18 July 2010.
  60. ^ Spitzer, Mark (2010). Season of the Gar: Adventures in Pursuit of America's Most Misunderstood Fish. U of Arkansas P. pp. 118–19. ISBN 978-1-55728-929-2.

External linksEdit