Cool cool! I've typed up the first post, will put it up soon. For now, here's what I've come up with for the monster.

Safikma
An amphibious serpent with the form of a snake and the gills of a shark. Created by the ocean deity Draconus, it lived for thousands of years like a small eel on the ocean floor. Upon the recent death of Draconus, however, its genetic programming was activated, and it began to consume and grow. At first other small fish and sea creatures served as its sustenance, but it rapidly gained size and moved onto swallowing entire dolphins, sharks, even whales. Before long its appetite grew to the point where it devoured a large fishing boat off the coast of Scara Brae. This satiated it for a week, at which point it returned to consume the village the boat came from. If not stopped, Safikma will continue growing and consume first the city of Scara Brae, and then the entire island, and eventually, the world.

Venex will be the one providing us with most of this info ICly so feel free to expand/add stuff to this, it's just a rough idea. What do ya'll think of the name?