Watch Freshwater Assassins (1947) Official Trailer

In a freshwater pond, it's "eat or be eaten." A dragonfly larva eats a midge; a water beetle larva eats a damselfly larva. Snail larvae grow. A beetle larva eats one. Up close, we see the eating apparatus of a damselfly larva—with a retractable hook beneath mandibles. Some creatures bite and chew, others suck. A water beetle larva holds on to its prey, injects a poison that turns the victim's insides to soup, and then sucks it dry. We watch one eat a damselfly larvae and then another water beetle larva. Some have ingenious ways to camouflage themselves, like the water scorpion, and to breathe air while hunting under water. Caddisfly larvae hide in debris, then eat.