World Without Fish by Mark Kurlansky Marine Science Earth Day Lesson is perfect for teaching about the importance of conservation, awareness to over-fishing, biodiversity, and ecosystems, toxins in food chains, human ocean pollution, evolution, adaptation, and extinction of the species. Concepts covered: The theory of natural selectionBiologically and commercially extinct fishBiodiversity & ecosystemOver-fishingHuman ocean pollution Effects of toxins in food chainOcean salinity and temperatures