Aside from the Alpha Series, Big Daddies communicate by haunting sounds similar to that of whale calls. Alpha Series communicate with low, inhuman grunts and roars. For easier interpretation (as stated in the Deco Devolution art book), production model Big Daddies have a mind controlling, bio-luminescent chemical substance which was filled into the helmet to display what state of emotion or mind that it is in. Big Daddy helmets have three light colors: green indicates the Big Daddy is hypnotized and friendly, yellow indicates awareness but indifference to his environment, and red indicates rage towards assailants. If the first few attempts to drive away potential threats prove futile, Big Daddies will become enraged, unlike Alpha Series who always begin enraged.
Big Daddies have become a staple in the BioShock games, becoming the face of the franchise.