The blue whale is the largest living creature on Earth. Usually, these whales are found in the cold Arctic and Antarctic oceans, but in the winter they are forced to travel to warmer waters for food. It is thought that there were once hundreds of thousands of blue whales, although today only about 1,000 exist. During the last century, blue whales were hunted for food and for whalebone, which was used to make women's clothing. In 1930, 30 thousand blue whales were killed by hunters. Today commercial whaling is banned, and it is hoped that one day, thousands of blue whales will be seen in the world's ocean again. The mechanism behind modern whale migration is debated since they are not as specific in their movement patterns as other species, and there is substantial evidence of alternative strategies, such as year-round residency, partial or differential migration, and anomalous habits such as feeding on breeding grounds. It is known that their natural predator is the orca, and the whales near the waters of California have been sighted with scars that prove their encounter.

Blue whales were solely protected in areas of the Southern Hemisphere starting in 1939, and such protection has been extended so much that today they are formally classified as endangered under the Endangered Species Act and are considered depleted under the Marine Mammal Protection Act. They are definitely a wonder of our oceans.