Big Bertha is a large species of Cheep-Cheep and the female counterpart of Boss Bass. They are apparently mothers of Baby Cheeps, as seen in Super Mario Bros. 3 where they spit them out of their mouths. Despite pretty much always being identical to Boss Bass, their most recent appearance in Lets-a-go, Mario gives them eyelashes. In the game, they also have trails of Baby Cheeps following them and give chase when the player approaches. Wendy O. Koopa can even summon 3 Big Berthas at a time which don't have babies and simply swim across the screen.