Whales are the largest marine mammal on earth. Orcas, killer whales are the largest of the dolphins and one of the worlds most powerful predators. All whales have fat layers of blubber, that help them in the cold. whalesWhales collectively inhabit all the world's oceans and number in the millions, with annual population growth rate estimates for various species ranging from 3% to 13%. For centuries, whales have been hunted for meat and as a source of raw materials. By the middle of the 20th century, industrial whaling had left many species seriously endangered, leading to the end of whaling in all but a few countries.