Spencer is a tough , muscular explorer and archaeologist named Dr. Smolder Bravestone ; Fridge is a diminutive zoologist named Franklin `` Mouse '' Finbar ; Bethany is an overweight male cartographer named Professor Sheldon Oberon ; and Martha is a female commando and martial arts expert named Ruby Roundhouse .
In Jumanji : Welcome to the Jungle , Fridge mistook the nickname of `` Mouse '' to `` Moose '' , and Bethany thought that Professor Sheldon Oberon was a woman based on the latter 's nickname .