North Polar Ghark

The ghastly snarks slowly migrated to the North Polar Coast. Here, they found an abundance of food. Thanks to this, they've grown larger. Their tail flaps have grown significantly larger, allowing going faster at the same energy cost, due to the high amount of water being displaced. Their dorsal fin has atrophied more, making them weaker, and thus more sustainable for rips. Due to this, and the hanging dorsal fin, they can get rips in their dorsal fin when the fin get stuck behind some rocks.