13 Mountain-fold the bottom corners in to slim the belly. Valley-fold the tail flukes down on each side. 14 Lift the flukes up, level, forming the tail. Valley-fold the middle of the head corner down. Mountain and valley-fold the large bottom corners to form a crimp on each side of the model. Look ahead at the next step for the shape. 15 Your model should look like this. Valley-fold up the pectoral flippers, bringing with it the bottom edge leading to the end of the head. Repeat on the other side.
16 Head detail: Valley-fold the top edge of the head down, narrowing the rostrum (beak). Mountain-fold the edges under the rostrum to further narrow the paper. Valley-fold the fin down at a forward angle. 17 Notice in this diagram that an eye has been suggested with a small deflection of the paper, where the back of the rostrum meets the front of the head.