Not shot with a significant telephoto lens (114 mm equivalent); this is probably as close as one should get to a mature alligator. The alligator opens his or her mouth for only two reasons; one, in order to cool off on a hot day or two, to menace.
This was not a hot day. (Safety note: I was in a vehicle.)
An apex predator, mature alligators are known to hunt deer, antelope, razorbacks, panthers and black bears.