Orpoises

Orpoises (carnificecetos) are a genus of porphin found worldwide. They are descended from oceanic porphins. They measure in at 8 ft in length and come in black and white. Plankton has become abundant in the Ariducene and therefore, the epipelagic zone has become abundant. This boom in productivity caused fish to get larger, which prompted some porphins to become more predatory. 

Their diet consists of large fish, squids, other porphins, and Megalotetraodons. Megalotetraodons are the only predator of orpoises, but orpoises will fight back and try to eat their predators. They are also able to dive down into the twilight zone, where they take down large descendants of sardines and squid. They have developed collapsable lungs and reinforced blood vessels to withstand the pressure.

Another quirk of theirs is their brutality. Pods go to war with each other over territory and mates constantly. Orpoises are also known to be cannibalistic and matriarchs are given calfs to eat. Their hyperagressive behavior indicates that they aren't the brightest. If they had the advantage of intelligence, they could easily become an apex predator, but their potential is untapped.