Originally posted by germanfryfan:
We also know that Dr. John Zoidberg is outraged when someone calls his mother a saint.
He was outraged in response to an accidental insult delivered by Fry, when he attempted to copy the sound Zoidberg made. Zoidberg's response, "What?!? My mother was a saint! Get out!!" implies that Fry must have inadvertantly slandered Zoidberg's mother.
More specific to the topic though, can someone remind me when Zoidy's mother appears on the show? I remember seeing someone who appeared to be more of an Aunt, but I can't remember a mother.
Anyway, it seems probable that if Zoidberg does have a living mother, she is his adoptive, rather than biological, mother (as Slackit said).