Gar

Gar
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Lepisosteiformes Family: Lepisosteidae
Species
Atractosteus spatula Atractosteus tristoechus Atractosteus tropicus Lepisosteus oculatus Lepisosteus osseus Lepisosteus platostomus Lepisosteus platyrhincus

Gar is the common name for any of the mainly freshwater, heavily armored fish comprising the family Lepisosteidae in the bony fish order Lepisosteiformes (or Semionotiformes), characterized by an elongated body and jaws, heavy ganoid scales, and needlelike teeth. Also known as gar pike or garfishes (ITIS 2004d, 2004e), they are one of only five living families in Actinopterygii (ray-finned fish) that are not included among the teleosts (Division Teleostei, modern bony fish) (Grande 2008). With fragments of fossils tracing to the Cretaceous, and complete skeletons known as far back as 110 million years ago, gars often are referred to as "living fossils" (Grande 2008).

Gars inhabit freshwater, occasionally brackish water, and very rarely marine water in eastern North America, Central America, and the Caribbean islands (Nelson 1994; Sterba 1962). The family includes seven living species of fish in two genera, ‘’Atractosteus’’ (broadhead gars) and ‘’Lepisosteus’’ (slender gars) (IT IT IS 2004a, 2004b, 2004c).

Description

Large gar at the Shedd Aquarium

Gar bodies are elongated, heavily armored with ganoid scales, and fronted by similarly elongated jaws filled with long sharp teeth. Tails are heterocercal, and the dorsal fins have few rays and are close to the tail. They have vascularized swim bladders (Nelson 1994, p. 85).

All the gars are relatively big fish, with the alligator gar (Atractosteus spatula) being the largest, reaching a maximum length of about 3 meters (9.8 feet) (Agbayani 2008; Grande 2008). Even the smaller species, such as Lepisosteus oculatus, are large, commonly reaching lengths of over 60 centimeters (2 feet), and sometimes much more (Kodera et al. 1994).

As their vascularised swim bladders can function as lungs, most gar 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. As a result, they are extremely hardy and able to tolerate conditions that would kill most other fish.

Distribution and habitat

Gars are found in eastern North America, Central America, and Cuba (Nelson 1994). In North America, they can be found as far north as Quebec in Canada and Montana in the United States and as far west as Montana (Grande 2008). Fossil gars are found in Europe, western North America, Africa, Madagascar, India, and South America (Grande 2008), indicating that in times past these fish had a wider distribution than they do today. There are no reports of fossil or living gars in East Asia (Grande 2008).

Gar usually are found in freshwater and in the shallow and weedy areas of rivers, lakes, and bayous, often congregating in small groups (Nelson 1994; Agbayani 2004).

Some species of gar are known to occasionally swim into brackish water or, very rarely, nearshore marine environments (Grande 2008; Nelson 1994). The alligator gar, for example, is caught in the salt marshes of Louisiana and has been observed in waters of the Gulf Coasts (Grande 2008). Likewise, Atractosteus tristoechus, the Cuban gar, enters brackish waters and is sometimes found in the sea (Agbayani 2004; Monks 2006).

Behavior

Gar tend to be slow moving fish, except when striking at their prey. They are voracious predators, catching their prey with their needle-like teeth, obtaining with a sideways strike of the head (Kodera 1994). Gar feed extensively on smaller fish and invertebrates such as crabs and frogs (Agbayani 2008; Grande 2008). Large alligator gars even feed on water birds (Grande 2008). Adult gars are large and armored, with thick scales and dermal bones, resulting in few predators (Grande 2008).

Gars spawning takes place in freshwater, involving external fertilization and the concentration of large numbers of individuals in shoal areas (Grande 2008). The black, highly toxic eggs are adhesive and stick to rocks, the substrate, or plants; upon hatching the larvae have adhesive suckers that allow them to stick to objects (Grande 2008). There is no parental care given to eggs or young (Grande 2008).

Taxonomy

The gars are members of the Lepisosteiformes (or Semionotiformes), an ancient order of "primitive" ray-finned fish; fossil gars are known from the Permian onwards. Their primitive traits are their very hard armour-like ganoid scales, a swimming bladder open to the pharynx that can function as a lung and the heterocercal tail. Gars are considered to be a remnant of a group of rather primitive bony fish that flourished in the Mesozoic, and are most closely related to the bowfin, another archaic fish now found only in North America.

Genus Atractosteus:

• Alligator gar Atractosteus spatula (305 cm)
• Cuban gar Atractosteus tristoechus (200 cm)
• Tropical gar Atractosteus tropicus (125 cm)

Genus Lepisosteus:

• Spotted gar Lepisosteus oculatus (112 cm)
• Longnose gar Lepisosteus osseus (200 cm)
• Shortnose gar Lepisosteus platostomus (88 cm)
• Florida gar Lepisosteus platyrhincus (132 cm)

Etymology

In British English the name gar was originally used for a species of needlefish, Belone belone, found in the North Atlantic, itself likely named after the Old English word gar meaning "spear". Belone belone is now more commonly referred to as the "garpike" or "gar fish" to avoid confusion with the North American gars of the family Lepisosteidae.

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

Significance to humans

Gar flesh is edible, and sometimes available in markets, but unlike the sturgeon that they resemble, their eggs (roe) are poisonous. Several species are traded as aquarium fish.

Cultural Significance

The Gar fish is of considerable significance to Native American peoples of the southeastern United States where the gar figures prominently in ceremonial life and music. See Creek, Seminole

Gar in aquaria

Gar are popular fish for public aquaria where they are often kept alongside other large, "archaic" fish such as sturgeon and paddlefish. However, a few species, most commonly Lepisosteus oculatus, are sometimes offered to aquarists as pets. They do of course need very large tanks but in all other regards they are easy to keep. They are not much bothered by water quality or chemistry, and are tolerant of a wide range of temperatures. Gar must be allowed to breathe air, so some clearance between the surface of the water and the hood is essential.

Gar get along well with any other fish that is too big to be eaten (such as large catfish, cichlids, and centrachids). They do not like aggressive tankmates, and despite being predators are essentially peaceable, sociable fish that do well with their own kind. Sturdy aquarium plants and bogwood can also be used to create hiding places, since gars are very fond of lurking in slightly shady regions.

Feeding presents no problems. Most will take all kinds of meaty foods, including mealworms, crickets, earthworms, frozen lancefish and shrimps (defrosted), and strips of squid. Oily fish (like salmon and mackerel) as well as fish guts will quickly pollute an aquarium but are very effective at tempting newly introduced specimens to eat. Once settled in many specimens will also eat floating pellets as well. There is no nutritional reason to feed gar live fish, and cheap feeder fish in particular tend to introduce parasites into an aquarium.

References

ISBN links support NWE through referral fees

• Grande, L. 2008. http://www.novelguide.com/a/discover/grze_04/grze_04_00254.html Lepisosteiformes (Gars)]. NovelGuide. Retrieved May 22, 2008.

• Agbayani, E. 2004. Family Lepisosteidae, Gars. FishBase. Retrieved May 22, 2008.

• Agbayani, E. 2008. Atractosteus spatula, Alligator gar. FishBase. Retrieved May 22, 2008.

• Integrated Taxonomic Information System (ITIS). 2004a. Lepisosteidae. ITIS Taxonomic Serial No.: 161092. Retrieved May 22, 2008.

• Integrated Taxonomic Information System (ITIS). 2004b. Atractosteus Rafinesque, 1820. ITIS Taxonomic Serial No.: 201896. Retrieved May 22, 2008.

• Integrated Taxonomic Information System (ITIS). 2004c. Lepisosteus Lacepède, 1803. ITIS Taxonomic Serial No.: 161093. Retrieved May 22, 2008.

• Integrated Taxonomic Information System (ITIS). 2004d. Semionotiformes. ITIS Taxonomic Serial No.: 161090. Retrieved May 22, 2008.

• Integrated Taxonomic Information System (ITIS). 2004e. Lepisosteiformes. ITIS Taxonomic Serial No.: 650224. Retrieved May 22, 2008.

Monks N. (editor): Brackish Water Fishes, pp 322-324. TFH 2006, ISBN 0-7938-0564-3</ref>

• Nelson, J. S. 1994. Fishes of the World, 3rd ed. New York: John Wiley & Sons. ISBN 0471547131.

• Nelson, J. S., E. J. Crossman, H. Espinosa-Pérez, L. T. Findley, C. R. Gilbert, et al., eds. 2004. Common and scientific names of fishes from the United States, Canada, and Mexico. American Fisheries Society Special Publication, no. 29.

External links

• Family Lepisosteidae entry at FishBase

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