If you kill animals with your ability, you gain their XP, a productive (but risky) way to evolve.
The Blue Whale, unlike most of the animals in the game, does not have a circular shape. It has a rounded body, its face protruding at the front, and a massive tail sticks out the back. Colored specifically in blue, its fins and tails are of a darker shade, and its sides have small highlights. Above its black rounded eyes is a black blowhole that blows out water or other loot when diving.
The Blue Whale's ability is used to knock predators and tail-biters away, similar to that of the Donkey's. It also can be used for stunning your prey; however, it needs great precision and accuracy, as you need to swivel around and aim for your prey as opposed to the elephant's ability.
If a predator is low on health, use your ability to slap them with your tail to either get them lower in health and stun them, and if possible, to kill them. A whale's ability can reach Crabs, Turtles, Dragons, and/or Black Dragons sitting on islands.
To level up quickly, go to the edge of the map (not the corner of the map or right next to some rocks or sandhills because you might have problems turning around to eat the animals). and wait till animals to tail-bite you then slap it with your tail and quickly turn around and eat it before it revives from the tail-slap.
Krakens have larger tails and are more open to tail-bites. If you managed to bite a kraken's tail, they normally activate their whirlpool ability, or they go after you. Either way, stun and push them back with your ability.
Teaming up with other blue whales, or elephants is advantageous, as pods of blue whales can easily kill a Kraken or a Dragon with their abilities. Even Black Dragons are vulnerable to a group of whales.
When you are alone and there is a big fight going on, dive and wait until some big level animal is at low health and turn your back against them and kill them do it fast and accurately. If you miss it, it could be your last. If you are accurate you can kill it and evolve. It should be very effective because a Blue Whale's slap does 1/10 damage to the animal.
Use your ability to eat Conches, and Mushroom Bushes, as your ability lets you eat them in one slap.
When on low health, don't run away instantly; use your ability against a predator in order to stun them and slow them down, and then escape. Beware of Black Dragons when running away, or anything which can eat you.