[6] Unusually, their vascularised swim bladders can function as lungs,[7] and most gars surface periodically to take a gulp of air.

[11] Confusingly, the name "garfish" is also commonly used for a number of other species of the related genera Strongylura, Tylosurus, and Xenentodon of the family Belonidae.

[13] Gars are considered to be the only surviving members of the Ginglymodi, a group of bony fish that flourished in the Mesozoic.

The oldest anatomically modern gar is Nhanulepisosteus from the Upper Jurassic (Kimmeridgian) of Mexico, around 157 million years old.

[17] Several different gar genera survived the Cretaceous-Paleogene extinction event, although they remained restricted to North America and Europe after this point.

Two short-snouted gar genera, Masillosteus and Cuneatus, are known from the Eocene in western North America and Europe, but disappear shortly afterwards.

Lepisosteus and Atractosteus show a similar initial distribution and eventual contraction, but both genera dispersed to eastern North America prior to their disappearance from western North America and Europe, with Atractosteus also dispersing further south to the Neotropics.

Eastern North America has since served as a vital refugium for gars, with Lepisosteus undergoing a diversification throughout it.

The distribution of the gars in North America lies mainly in the shallow, brackish waters off of Texas, Louisiana, and the eastern coast of Mexico, as well as in some of the rivers and lakes that flow into them.

[20][21] A few populations are also present in the Great Lakes region of the United States, living in similar shallow waters.

Experiments on the swim bladder has shown that the temperature of the water affects which respiration method the gar will use - aerial or aquatic.

Proximally to the postcleithrum, the supracleithrum is important as it plays a critical role in opening the gar's jaws.

The largest alligator gar ever caught and officially recorded was 8 ft 5 in (2.6 m) long, weighed 327 lb (148 kg), and was 47 in (120 cm) around the girth.

[28] Even the smaller species, such as Lepisosteus oculatus, are large, commonly reaching lengths of over 60 cm (2.0 ft), and sometimes much longer.

They prefer the shallow and weedy areas of rivers, lakes, and bayous, often congregating in small groups.

This list also includes definitively known fossil taxa, common names for which are based on Grande (2010):[7][31] A. tropicus A. tristoechus A. spatula L. oculatus L. platyrhincus L. osseus L. platostomus Family Lepisosteidae The largest member of the gar family, the alligator gar (Atractosteus spatula), can measure up to 10 feet long and weigh over 300 pounds.

[35][36] Recreational fishing of the alligator gar became popular due to its massive size and its meat is sold for food.

[38] Over five decades of overfishing have brought it close to extinction,[36][37] and man-made dams have contributed to this loss by restricting the gar's access to the flood plain areas in which it spawns.

Some states also impose a minimum length requirement to prevent gar from being caught at too early an age.

[46] The shortnose gar (Lepisosteus platostomus) is found in the Mississippi River Basin, Indiana, Wisconsin, Montana, Alabama, and Louisiana.

[48] The shortnose gar has a lifespan of 20 years, reaches up to 5 pounds in weight,[49] and grows to lengths of 24–35 inches.

[47][49] It consumes more invertebrates than any other gar,[48] and their stomachs have been found to contain higher Asian carp content than any other native North American fish.

[51][54] The flesh of gar is edible, but its eggs contain an ichthyotoxin, a type of protein toxin which is highly toxic to humans.

[59] Not much is known about the precise function of the gar in Native American religion and culture other than the ritual "garfish dances" that have been performed by Creek and Chickasaw tribes.