Monolisk

The monolisk is a large mammal that breathes water. Its sleek hide is glossy black, striped in gray from snout to tail.

It harms other creatures only to eat. Once per hour it can charge the water within 30 feet, stunning everything there for 2d4 rounds and floating it to the surface; a save vs. spell shrugs off the shock. It then gulps down its catch. It eats any flesh, from fish to land creatures to prey larger than itself, swallowing what it can whole and biting the rest into as few pieces as possible.

Attacked, it strikes back by reflex with a bite for 2d4 or a tail slap for 1d6. It may use both in one round only against two different foes, and tail swipes always suffer -4, since its eyes cannot track anything beyond the edge of its sight. Each 20 points of damage it suffers forces a morale check, and failure sends it fleeing.

Against air-breathers in the water it holds the advantage, able to come at them from any direction, including straight up from below to ram or from above in a dive.

Monolisks hunt alone, which fishermen appreciate, unlike sharks and other pack predators. They pair up only to help a sick or wounded companion and otherwise squabble over feeding grounds, sometimes even fighting over stretches of water with nothing in them to eat.

A monolisk lives about fifty years and breeds just ten times. Pregnancy lasts three years and yields a single pup; twins kill the mother 90% of the time. Young stay with her for two years before setting out alone. Few mammals anywhere breathe water, and the kraken prizes the monolisk as prey, sometimes trailing a single one for weeks.