Merely use a Great White Shark alias Jaws model and select its BODY and scale it bigger. If anyone knows of a realistic detailed Great White Shark model, it could be made into a Poser model, including getting its throat to distend as it swallows something big. If you want something that does that job but is mechanical, I made a model of a suitable device, see this link. The sub is in the Poser Free Stuff.