Step 15: Add a few more lines and shapes within the body for extra detail. Draw a series of long, curved lines along the humpback whale's bottom jaw for the ridges and grooves found here. Don't draw too many lines. Just a few for the texture. Add some on the underside of the whale's body to the right of the flipper too. About halfway between the flippers and the tail, on the underside of the body, draw a curved shape for markings found there. Add some lines along the right side of the body for more creases and detail on the skin.
Step 16: For a cleaner look, erase as much as you can of the initial guide lines. Don't worry about erasing all of the guides. It's okay to leave some behind. Re-draw any final sketch lines you may have accidentally erased.
Final Step: Add some shading to your drawing for extra detail. Humpback whales don't have a pattern on their bodies like spots or stripes, so just add a medium value all over. Leave a few circular shapes on the tip of the mouth blank for the white bumps and barnacles. Leave the section with the ridges at the bottom blank. The splotchy marking and the flippers should be blank too. For a more detailed guide on how to shade, check out this tutorial: How to shade.
Use a slightly darker value along the bottom of the humpback whale's body to make the shape rounder and to give it more dimension. Vary the pressure on your pencil to get different degrees of tonal value. As you shade, use long, smooth, horizontal strokes for a sleek surface. Avoid a rough and gritty texture. Use a lighter value on the top side for a rounder shape and to give the body more volume. Shading can be time-consuming, so be patient and take breaks.
Shade lightly at first, and then gradually build up to the level of darkness that you like. Don't push down too hard on your pencil though or the graphite may become shiny, and you may tear your paper. It's a good idea to use reference as you draw for an accurate depiction of a humpback whale.
Draw a series of irregular shapes for the spots on the underside of the body and flippers. Your spots don't have to look exactly like mine. Don't overthink it. Just add different-sized splotches throughout the white areas. Don't cover all the white areas with spots. Leave some large areas blank, especially on the flippers. Add some light value along the white underside of the whale's body for a shadow. This makes the figure more three-dimensional. Don't forget to pause the video after each step to draw at your own pace.