We usually think of a predator catching prey in its teeth, then swallowing it. The gar (fish) seen in the following video has special adaptation that suddenly increases the volume of its throat as it opens its mouth, thus causing the sudden inrush of water, which may carry a small fish with it. This is best seen in the portion of the video near the end (31-35 seconds) Note the small fish swimming near the side of the gars mouth. Now you see it; now you don’t, but the gar didn’t move its head toward the fish. It only opened its mouth. (Replay it several times to get the picture.) Please post questions.
Note that science does not always involve experimentation. Often times, it only takes careful observation. https://www.sciencemag.org/news/2019/03/alligator-gar-sucks-lightning-speeds?