Predators must have started their evolution soon after life was first established in the primeval soup with the primitive bacteria devouring plastid and mitochondria carrying entities.It evolved from the minute to the gigantic extinct dinosaurs and the largest killer whales or orcas which are still with us. These water beetle larva perform just like a fox terrier or a cat foraging after a mouse. Burrowing into the debris and rootlets of the duck weed in the petri dish with considerable aggression and energy.The action is the same though there are six legs instead of four. One could almost imagine them thinking. Their prey some unidentified spherical animals.All the predators have their niches and the prey fits the size of the predators. If the predator is very small and the prey large then I suppose it becomes a parasite. That's a bit rough and derogatory.
See the video of the attack. Just like a lion grabs a wildebees by its throat and suffocates it until its dead, this predator held the prey until it was dead before eating it.