I think I will try this technique again using a more abstract approach. And I have to teach them not to press down so hard when they color with the pastels. Blending light scribbles worked the best.
One book I love to read when I teach about sea turtles is Turtle Tide: The Ways of Sea Turtles by Stephen R. Swinburne.
Fun Fact: The temperature of the sand in which the sea turtle lays her eggs determines the sex of the babies. The warmer the sand, the more females will be born.