When you think of marine life, you probably think about scaly fish with gills, but there are a variety of aquatic mammals that breathe air. So hold your breath and dive into the marine mammals quiz!
Whether you're sleeping on a water bed or napping during a rainstorm, water has a calming effect. Walruses also make use of soothing waves, but why don't they drown when catching submerged shut-eye? See more »