Step 15: Use the line at the top as a guide to draw the tail. Draw the shape of the tail around the guide. Make the base thick and the tip pointy. On the top edge of the tail, draw a short, thin, pointy shape for the stinging spine. Add a couple more curved lines to the stingray's tail for the other fins.
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 stingray drawing for extra detail. Some stingrays have patterns on their bodies, but for a common stingray like this one, just add an even medium value all over. Shade lightly at first and slowly build up to a medium or darker value. Vary the pressure on your pencil to get different degrees of tonal value. Don't shade the inside of the eye. Shading can be time-consuming, so be patient and take breaks. For a more detailed guide on how to shade, check out this tutorial: How to shade.
Use a lighter value to shade the underside of the stingray's wing. Use a darker value around the head and along the edges to give the body more structure. It's a good idea to use reference as you draw for a more accurate stingray drawing. Continue to gradually add a darker value throughout the body until you're happy with the result. Don't forget to pause the video after each step to draw a your own pace.