Give each teacher involved a part to complete within the mural.
One class will have each student create a creature that has descriptive words unique to the student in each section of the creature. Students can choose to color their creature if they wish, depending on how much time you want to give students to work on their creatures.
One class have each student cut and color the other creatures for the landscape. (i.e., jellyfish, sea stars, fish, etc… for a sea landscape).
One class will collect the creatures from the previous classes and uses hot glue guns to add the creatures to the landscape they create with bulletin board paper.