Longbourne's physical alien appearance resembles a gray eel with a purple spine, only added with arms, two pairs of legs, and his eyes peer from inside his mouth, due to his eyestalks being attached to his tongue.
Longbourne is seen when this feature is comically used as a justifiable excuse such as when he sticks his tongue out at Arrow when he is scolded for encouraging a brawl between Jim and the most dangerous insectoid alien named Scroop. During the voyage, the ship encounters a supernova. While securing lifelines of all pirates so that they will not get lost, Jim saves Silver from falling just in time. The supernova then devolves into a black hole, where Arrow falls to his death. The burst of shock waves and maximum engine power enable Amelia to pilot the ship to safety. Amelia mourns the loss of Arrow, and suspects Jim of failing to secure the lifelines, while Arrow's line was actually cut by Scroop. He is also one of the first three pirates, the other two being Fayvoon and Hands to die in the film, when a misfire from Doppler resulted in falling debris, destroying the floorboards and sending the pursuing pirates falling out of the ship's longboat room from a great height to their apparent deaths. It is unknown if Longbourne and his fellow pirates survived the fall or not, but even if they survived, it is highly suspected that they were severely and mortally injured by it or were eventually and definitely killed when Treasure Planet was blown up by Captain Flint's trap.
- Longbourne, Turnbuckle, Blinko, Hands, Fayvoon, Scroop, Captain Flint, and his pirates are the only villains who died in the film.