The "Gator" that isn't...

Named for its resemblance to alligators, the alligator gar (Atractosteus spatula) is the largest of all the known gar species. Found throughout the lakes, bays and bayous of the US Southeast, this toothy freshwater behemoth is considered to be a “primitive” fish or living fossil because it still retains some of the physical features of its prehistoric ancestors.

For example, their scales differ from those of most other fish, as they are composed of an inner core of bone and an enamel-like outer layer that’s similar to our own tooth enamel and which is nearly impenetrable. Indeed so durable are they that Native Americans in the southern US and Caribbean used to use the alligator gar’s scales for arrowheads and even breastplates.

These aquatic giants may look fierce, but there are no known records of any attacks against people. They can pose a passive danger, though, as their eggs are poisonous to humans if eaten. While they understandably have few natural predators, they have been known to fall prey to the alligators they resemble, and whose jaws are simply too powerful for even the gar’s enamelled armour to withstand.

But if their wide, tooth-filled snouts, armoured hides and powerful, torpedo-like bodies weren’t enough to ensure their survival, they have another vital trick that they can call on. Thanks to a special “swim bladder lung” that’s fed by an ample blood supply, they are able to supplement the oxygen taken in by their gills by breathing in air from the surface and thereby surviving in water that would suffocate many other fish.