Grass gators have code that tell them to submerge and resurface in shallow waters if they swim out too far into deep water.
However I noticed that for some reason, they can resurface in the ground, and when they do they turn invisible and their A.I stops working.
You can collide with them in this state and changing their state, I.E: Attacking/freezing them will return them to normal.
I believe this also happens when they spawn and are near land(or a boat), which they have animations for but don't seem to be used. I may be mistaken on this last bit though.
(The dark shadow is the Gator in question.)
Bring a Gator nearby land, let them run off into the ocean until they submerge.
Watch as they surface and merge into the ground, breaking.