Earth is a water planet-almost two-thirds of it is covered by ocean-and while a sliver of life exists on land, most of the planet's population thrives in the seas. Life underwater requires special adaptations that sound more at home in a special-effects lab than in one of the earth's largest ecosystems. Internal lights help dwellers of the deep seas pierce the darkness. Regenerating teeth keep hunters armed and sharp. Color-changing abilities hide vulnerable animals from predation. From the Great White Shark at the top of the food-chain to the Leafy Sea Dragon at the bottom, readers can explore what it takes to survive in this extremely crowded, high-pressure, watery world.