Zoology

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Entries - Entry Category: Zoology - Starting with G

Gars

aka: Garfish
aka: Garpikes
Gars are a primitive group of euryhaline fishes dating back to the late Jurassic to early Cretaceous Period, about 150 million years ago. Gars are one of the most recognizable fishes because of their slender torpedo-shaped bodies, ganoid scales, and long snouts with numerous teeth. Dorsal and anal fins are set far back on the body, and the caudal fin is rounded, with a condition known as abbreviate-heterocercal. Gars are unusual among fishes in that their vascularized swim bladders can function as lungs; they must surface periodically to take a gulp of air. Arkansas hosts four gar species: the alligator gar (Atractosteus spatula), spotted gar (Lepisosteus oculatus), longnose gar (L. osseus), and shortnose gar (L. platostomous). Fossilized gar specimens have …

Gastrotrichs

aka: Hairybacks
The Phylum Gastrotricha (commonly called “hairybacks”) comprises about 800 species of marine, brackish, and freshwater microscopic invertebrates. Twelve genera and fewer than 100 species of freshwater gastrotrichs are known from North America. However, in North America, perhaps 75 to 90 percent of the probable diversity of freshwater gastrotrichs species are undescribed. Gastrotrichs are widely distributed cosmopolitan organisms that are divided into two orders: the Macrodasyida (with nine families), which, except for two freshwater species (Marinellina flagellata and Redudasys fornerise), are marine, and the Chaetonotida (seven families), some of which are marine, estuarine, and semi-terrestrial forms, while others are primarily found in freshwater. The Chaetonotida can be further broken down into two suborders: the Multitubulatina (Nesodasys) and the Paucitublatina (Chaetonotus, Dasydytes, …

Goldeyes and Mooneyes

aka: Mooneyes and Goldeyes
aka: Hiodontid Fishes
North American freshwater fishes of the family Hiodontidae (order Hiodontiformes or Osteoglossiformes) include the goldeye (Hiodon alosoides) and mooneye (H. tergisus). The goldeye ranges from James Bay (bordering the provinces of Ontario and Quebec) in Canada and the Mississippi River basins from the Northwest Territory to western Pennsylvania and Ohio south to Louisiana. In Arkansas, H. alosoides is found sporadically in lakes and the larger turbid rivers of the state, including the Arkansas and Mississippi, and the smaller Black River. The mooneye (also called the “freshwater tarpon”) ranges from the St. Lawrence–Great Lakes, Mississippi River, and Hudson Bay basins from Quebec and Alberta, Canada, east to western North Carolina and south to Louisiana. In Arkansas, H. tergisus occurs in large …