American alligator (Alligator mississipiensis) Its lower jaw and mouth is partly covered in duckweed (Family Lemnaceae). When hunting this crocodilian reptile floats at the surface of water with its body completely submerged except the top of its head. In this way, it can spring on unsuspecting prey. The duckweed marks the level the water came up to. Photographed at Alligator Bayou near Baton Rouge, Louisiana, USA.