Seagrass, also spelled sea-grass, is a flowering plant that grows on the ocean floor. Seagrass has long, thin leaves and grows in large grass-like meadows. Seagrasses are found in hot and cold salt waters from Australia to Alaska and because seagrasses need sunlight to photosynthesize they only grow in shallow water. Like mangroves and coral reefs, seagrasses are an important ecosystem. They provide food to a variety of sea life including dugong, manatees, green turtles and even geese. They provide shelter to crabs and lobsters and protect young fish from large predators. Seagrass beds slow currents and waves protecting the coast and sea floor from erosion. What's more, seagrasses help keep oceans clean. They purify the water and ensure it is oxygen rich.