Atractosteus

Atractosteus is a genus of large, predatory fishes in the gar family Lepisosteidae. The genus includes several living species, notably the alligator gar (Atractosteus spatula) and the tropical gar (Atractosteus tropicus). Gars are among the larger freshwater fishes of the Americas and are easily recognized by their elongated bodies, long jaws filled with sharp teeth, and heavy ganoid scales that give a diamond-like appearance.

Anatomy and physiology: Members of Atractosteus have elongated snouts and jaws, with numerous conical teeth adapted for grasping prey. Their dorsal and anal fins are situated toward the tail, aiding stability while pursuing prey. They possess a primitive gas bladder–derived organ that can function as an additional airway, enabling limited air breathing in hypoxic waters.

Distribution and habitat: Atractosteus species are native to the Americas, ranging from the southern United States through Central America to parts of South America. They inhabit a variety of freshwater and brackish environments, including rivers, lakes, floodplain systems, and estuaries, often preferring warm, vegetated, and shallow waters.

Ecology and life history: These gars are ambush predators, feeding primarily on fish but also taking amphibians, crustaceans, and occasionally birds. They reproduce by external fertilization in shallow, vegetated areas during the breeding season. Juveniles and adults display different habitat uses, with juveniles often occupying different microhabitats than adults.

Taxonomy and conservation: The genus falls within Lepisosteidae and has a long fossil record, reflecting its status as a primitive lineage among modern ray-finned fishes. Conservation status varies by species and region; some populations have declined due to habitat alteration and overfishing, while others are not considered threatened.