Ninevet

The Ninevet is an almost totally aquatic amphibian, a strange and loathsome carnivore that inhabits marshes, swamps, lakes, or slow-moving rivers throughout Middle-earth. It is very common in the Nindalf (Wetwang) marshes. Ninevet float just below the surface of the water, looking (if they are visible at all) like dead logs. When they spot a potential victim (anything from a duck to a man, depending upon the size of the Ninevet), they erupt directly below it, stunning the creature. If it is a small enough creature, the prey is swallowed immediately. Otherwise, the Giant Hellbender wrestles its victim to the bottom with its leathery paws and sharp claws, holding it down until the struggle ceases. It then swallows the victim at its leisure, relaxing and expanding its flexible maw to lit the meal at hand. Ninevet can go for weeks without eating, but have little stamina in action, so any creature large and strong enough to offer a protracted struggle may be released as the Ninevet swims off in search of easier prey.