Who is Grendel from Ice Hunt and what is their importance?

Grendel is the evolutionary link between whale and land mammal, a Grendel has two slitted nostrils high on its head. It weighs as much as a ton and measures up to ten feet in length. It has lips behind which are razor like teeth. It is white skinned and hairless and its body is sleek. It has shoulders that are well muscled and a domed head. It is quick, and uses teeth and claws to subdue its prey. It moves lithe and sinuous, like an otter and has black eyes. It has forelimbs with raking claws and large, webbed hind legs.