Maybe snakes? The animation would be fairly simple, just giving the snake more coils in front and fewer in back, while moving the head and tail. There would be many types of snake, such as the emerald tree boa, which can climb trees, the anaconda, which traps and strangled it's prey, and the spitting cobra, which can cause mild poisoning and blindness at a distance, and the sea snake, which can attack sharks. Snakes, when killed, give you venom and nothing else. Different snakes would cause poisoning at different rates, and these different poisons would carry their effects to the arrows they are used for. Strong poisons would reduce the amount of meat dropped, because it would be contaminated. Snake antivenom would also be available. Because snakes find their prey using heat detection, you could get closer to a snake undetected in hot places. Snakes would be attracted by fire and have about 5 hit points.