Have your students cut a large oval out of construction paper for a fish body. Then have them draw and cut out the various body parts using a variety of colored paper. They might cut out eyes, scales, fins, gills and a mouth. Have your students identify the various parts of the fish as you go around the room. Since scales might take a long time to cut out individually, consider handing out circular stickers, which can easily adhere to the fish body.
Cuttlefish change color to communicate with other cuttlefish. Divide the class into groups, each with a set of three colored cards cut from construction paper. Each group will devise a system of communication to indicate things like food, danger, turn left, turn right. Each group will have a turn to be led around by its leader, seeking "prey" that has been hidden in the room. Members seek independently, though in the pack. When one member finds a "predator" the team is out. When a team finds the "prey" the game is over. Follow up the activity with a discussion of which communication methods were best, and why.
Introduce the lesson by reading from Jules Verne or even Melville, demonstrating how sea creatures have a significant place in literature. Then have students pick their own sea creature to research and write a creative story about. Students should include realistic details about their animals to bring the story to life. You may elaborate on the activity by having students illustrate their stories with hand-drawn pictures or cutouts from magazines, or even a mix of the two.
Pair students off and have each pick a species of shark from a hat, which they will research for the project. Each pair will devise a series of questions for the shark, then use the library to research their particular shark. Questions might involve feeding patterns, migration, physical characteristics, whether or not they've been known to attack humans, or other questions. Encourage creativity and allow students to create their own scenarios for the interviews, perhaps swapping roles during their presentation or creating plays based on the facts they found in the library.