The gars are a successful family of ray-finned bony fish from the Late Jurassic-Holocene of the entire world. They were named in 1803 by Jean Léopold Nicolas Frédéric, Baron Cuvier. They are one of the few animals to be called "living fossils" (due to surviving up until now); as well as this, similarly to other "living fossils", they used to have a worldwide distribution, but are now only limited to bodies of water near a single landmass (in this case, the Americas).
Physiology[]
Gars vaguely resemble more typical ray-finned fish, having a long, streamlined body and rounded pectoral (arm), dorsal (back), pelvic ("leg"), anal (rear) and caudal (tail) fins. However, unlike more typical ray-finned fish, gars lack a spiny dorsal fin; as well as this, their soft dorsal fin and their anal fin are in close proximity to their caudal fin, and their jaws are elongated and filled with sharp, interlocking teeth, giving them a vaguely crocodile-like appearance. Their bodies are covered in scaly skin.
Diet[]
Gars are predators, feeding mainly on crustaceans and smaller fish, but also sometimes snacking on birds, small mammals, and turtles. Their teeth are long and needle-like, and are used to get a hold of slippery prey; some species of gar, such as the alligator gar (Atractosteus spatula) have two sets of teeth to further assist in prey capture.
Ecology[]
Gars are slow-moving ambush predators that inhabit slow-moving or tranquil freshwater ecosystems, such as lakes and bayous; when hunting, they often put on a burst of speed to catch up with their prey before snagging it in their jaws with a sideways swipe of their heads. Their elongated, interlocking bony scales give them a tougher body than that of most other fish; these scales rest upon a network of collagen fibers that further reinforce them, allowing them to withstand a fair amount of damage. Along with this, they have specialized swim bladders that function as lungs, allowing them to rise to the surface to swallow air; this allows them to survive in low-oxygen water caused by algal blooms in their ecosystems. As well as this, their eggs contain a poison that induces vomiting, diarrhea, dizziness, and decreased blood pressure in humans; surprisingly enough, while this poison kills small mammals, birds, and even crustaceans, it has no effects on other fish, meaning that it likely was not evolutionarily selected for as a means of protection, and may have only arisen via coincidence.