Step 15: Use the line at the top as a guide to draw the fourth tentacle the same way. Be sure to draw the base thick and gradually make it thinner toward the tip. Because this tentacle is curved, add a few short, curved lines along the outer edge for the suction cups. Octopuses have two rows of suction cups per tentacle, so add a few short, curved lines within the shape as well.
Step 16: Use the lowest line on the right side as a guide to draw the octopus's next tentacle. If you curved your initial guide line like this one, drawing the tentacle can be tricky, but just follow the path of the guide. This tentacle is curved in a way that the bottom section is facing us, so some lines will overlap.
Pause the video to draw at your own pace. If the tentacle is getting too complicated, you can always straighten it out. This tentacle is curling a lot more than the previous ones, so the suction cups will be at the tip and on the right side. Make the right, curved edge of the tentacle bumpy for the suction cups. Add a series of short, curved lines within the octopus's tentacle for the second row of suction cups.
Step 17: Use the next line up as a guide to draw the octopus's sixth tentacle. For an easier way to draw a curved tentacle, draw it in profile or the side of it and don't worry about the underside. Using this method, you just draw the side of it without much of the bottom and suction cups showing.
Step 18: Use the last line as a guide to draw the final tentacle. This tentacle is stretching away from the body, so the underside shouldn't be too visible. You can stop here and assume that the last tentacle is stretched out behind the octopus's body. If you'd like all the tentacles to show, you can add one more somewhere else around the body. You can either freehand the eighth tentacle or start with a guide line like with the others.
Step 19: 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 (optional): Add some shading to your octopus drawing to give it more dimension and volume. Pick the direction of the light source when shading so that the shadows are consistent with it. Because the octopus will be at the bottom of the ocean floor, the light will come from the top, so the shadows will be mainly near the bottom. Vary the pressure on your pencil to get different degrees of tonal value. Try to add the value smoothly for an even surface and avoid a rough, gritty texture. For a more detailed guide on how to shade, check out this tutorial: How to shade.
Add a cast shadow underneath. This helps ground the octopus so it doesn't appear to be floating. You can also skip this step and instead draw a few circles around the octopus to represent bubbles as it floats in the ocean.
You can add even more value throughout your drawing for extra detail. Octopuses can change the appearance of their skin, so you can shade yours any way you want. For a simpler drawing, add a medium value all over the body except to the underside of the tentacles. Adding the value can be time- consuming, so be patient and take breaks. It's always a good idea to use reference as you draw. And don't forget to pause the video to draw at your own pace.