Gulper

The gulper is little more than an immense hinged mouth trailing a whiplike tail of startling length, and that mouth can engulf creatures several times its size. Real deep-ocean gulpers, such as the pelican eel, run from half a foot to 6 feet without the tail, but fantasy varieties reach 12 feet. Tiny eyes sit atop the head to catch the faintest light from above, though the fish hunts mainly by sensing movement through its lateral line.

Its bite inflicts 2d8 hp damage, but only once: after that the victim is inside, and the teeth merely hold it in place while digestive juices eat away 1d8 hp damage each turn until the meal is freed or dissolved. Cutting a comrade out is risky, since every point of damage dealt to the gulper's soft body is also dealt to the trapped victim. Gulpers can also coil their tails around a victim for 1d6 hp damage per round, and a 12-foot specimen can strangle anything smaller than size G.

Gulpers live alone and have almost no brain to speak of; a 10-inch pelican eel has a braincase a quarter-inch long. Their breeding is unknown, though a parent may shelter its fry in its mouth for a while, and a sensible youngster leaves before the parent's hunger wins out.

A gulper eats anything and is quite good to eat itself, with delicate flesh. Enterprising magical crafters have used its stretchy skin to make bags of holding.