Humpback Whale, is a whale and a premium friend in Abyssrium. Like other premium friends it is purchased along with a package with real-life money, and it isn't need to unlock any other friend.
To unlock Humpback Whale is necessary to buy the Master Package ($50), wich is unlocked at level 750.
Humpack whales are very well-known due bull's habits of "singing", and jumping out of water during the mating season. They spend the winter in warm oceans, and summer in the Antartic Ocean. They have a very interesting habit of hunt krill, making a net of bubbles then, they go under the net and eat the krill.