narwhal: unicorn of the artic by candace fleming
You are a narwhal.
Shy... Swift... Small...
Humans call you unicorn of the Arctic.
When winter ice covers the Arctic Ocean, a narwhal pokes his head through a patch of open water, his tusk--a six-foot long tooth--pointed to the sky.
Join this mammal as he jousts with another narwhal, floats with his pod, and uses echolocation to find his prey. When warmer weather arrives, he will migrate towards summer ground. But he must be careful! Predators--orcas and polar bears--will be hungry and looking for a meal.... How will the narwhal escape? Will he be able to return to the winter bay? - goodreads