Many different kinds of sharks are swimming below the ocean's surface: Some sharks are gentle, and some are fierce; some are awake in the day, and some are awake at night. You may know the tiger shark and the thresher shark, but how about the lemon shark, longnose sawshark, and the cookiecutter shark? There's no gore or scariness here, so prereaders can learn the names and enjoy Michael Paul's colorful illustrations.