The Phosphorescent Rat is the fourth album by the blues rock group Hot Tuna, released in early 1974 as Grunt FTR-1010. This was the first Hot Tuna album recorded after guitarist Jorma Kaukonen and bass player Jack Casady had left Jefferson Airplane. They were joined as before by drummer Sammy Piazza, though Papa John Creach had left the band for Jefferson Starship.