Thresher is a bloodthirsty fighter, using battles with enemies as an excuse to eat them. Despite his feral nature, Thresher is surprisingly noble at times, such rescuing a human girl from an angry sailor (and eating the man's arm in the process). He is apparently involved with Moray. When a giant mutated crab attacks the Sea Devils' home city, Thresher sacrifices himself by strapping a gravity bomb to his back and swimming down the monster throat.
Thresher has all the natural abilities of a shark. He can smell the slightest drop of blood in the water, swim incredibly fast, breathe underwater, and can even detect the bio-electric fields of living creatures. But the ability he is best known for is his incredible bite, that can sever human body parts with a single snap of his jaws.