Narwhals and other whales

"When Jack and Annie came back from their adventure in 'Magic Tree House #33: Narwhal on a Sunny Night,' they had lots of questions. What is a narwhal? Why is it nicknamed the unicorn of the sea? What other whales live in the arctic? How do they survive the cold? Find out the answers to these questions and more as Jack and Annie track the facts about narwhals and other whales"--Provided by publisher.