I'll continue by selecting each joint after that (moving toward the flukes), and give each of them a slight rotation until I have a reasonable curl that is typical of a sperm whale.

Here occurs a critical part of the model-builder's art. The lines of the mesh must be laid out in such a way and be of sufficient density around the skeleton's joints so that when the user "bends" the joints the mesh does not deform in unexpected ways.

For my sperm whales, I made the mesh in the back half of the whale much more dense than I made the head area. Sperm whales do not have a very flexible head or any real neck. So, the mesh is made to have lower density and somewhat less detail in the front than at the rear. And, as you can see in the prior illustrations, the skeleton is much more detailed (has more and smaller joints) in the rear than it does in the front.