With a black pencil, you can draw lines that are dark and rich, or soft and powdery if you don’t press too hard. However, be careful because lines made with this pencil don’t blend well.
First, redraw the marine animal with the black pencil. Then erase the original gray pencil lines as much as possible.
To add “color” to the body, press lightly on the tip of your pencil and shade certain areas. This will create a soft-looking surface.
Gradually darken parts of your drawing to bring out the shape of the body and to add small details to the fins. When drawing a shark, make sure to keep the stomach clear.