Step 1 : Introduction to the question "2. Which aquatic mammal possesses a single forward-facing tusk of up to ten feet in length, earning it the scientific name Monodon monoceros or "onetooth unicorn"? "
...1. beluga whale 2. great tusked sperm whale 3. irrawadi dolphin 4. narwhal Narwhals are also noted for their deep-diving abilities. They routinely descend to depths of up to one mile below the surface.
