Stage 1 - Dolphin

First I created a cylinder then in the modifier panel pressed the Calapse button while the end vertices's were highlighted.

Next I reshaped the cylinder so it thinned out at the tail end. I then selected the polygons where the fins will be then clicked on the Bevel settings button and changed the height and outline amount to the desired amount.

Next the tail needed forming. This was done by using the slice plane and the slice button to create some new vertices's. Then I selected the end of the shape and clicked on the Bevel settings again, this time I selected the 'By Polygon' setting which bevels each polygon individually I then changed the parameters accordingly.