Jake is Michael's best friend in Jaws: The Revenge. He is shark's third victim, when he plants a shocking device in the shark's mouth, that will drive the shark crazy, by standing on the boat mast of Neptune's Folly, with the shock device tied to a long stick. The shark emerged from the water and moved straight up out of the water, on its tail as Jake successfully planted the shocking device into the shark. But Jake lost his balance on the mast and fell in the shark's mouth and the shark mauled him as the shark broke part of the mast and dived back in the water, still biting a hold of Jake. Amazely, Jake was still alive, as he was hitting the shark with his hands as the shark took him underwater. Luckily, Jake survives the attack (in the new ending), later on, when the shark is blown to bits, due to Ellen stabbing the shark with the sharp boat mast that hit the shock device that was inside the shark, causing the shark to blow up. It is unknown if the shark actually ate Jake or spit him out because he wasn't a Brody or the shark was already feeling the effects of the shock device. It's likely the shark spit Jake out, because he wouldn't be alive if the shark did eat him up.
Jake was found by Micheal, when after the shark's demise, he, Ellen and Hoagie fell in the water and Neptune's Folly boat sanked; Jake was still seriously injured, but still alive. Jake declared to Micheal that from now on they're going to study snails.
In the novel, Jake's last name is McCoy. But he's last name is never mentioned in the film.