Step 10: Use the top part of the arc as a guide to draw the top of the blue whale's mouth or rostrum. Follow the path of the arc as you darken the line. At the top, draw a small bump for the splashguard and a line for the blue whale's blowhole.
Step 11: Use the initial arc as a guide to draw the blue whale's pectoral fin. Draw the top of the fin closer to the head. Bend the left side of it a bit more. Draw a line inside of it on the right side for extra detail.
Step 12: Use the triangle-like shape on the left side as a guide to draw the blue whale's flukes. Follow the basic path of the lines but make them curve more as you darken them. The ends of the flukes should be pointy. The middle portion should dip in toward the body.
Step 13: Draw the top of the blue whale's body by using the initial lines as guides. Follow the path of the guides but bend the body up more as you darken the line. Draw a small, pointy triangle-like shape above the circle on the left for the blue whale's tiny dorsal fin. Sketch lightly at first, then darken the lines when you get the structure right.
Step 14: Use the remaining lines as guides to draw the bottom portion of the blue whale's body. Sketch lightly as you follow the path of the guides to get the structure right. Bend the line more near the circle on the left to simulate movement and not have the blue whale so static.