In the same manner, by which most octopuses on the show are modeled after Squidward, Betsy Krabs is very similar to her son in terms of appearance. She has wrinkly light red skin, wears a purple dress and large blue glasses, and has a small patch of fluffy white hair. In "Mid-Life Crustacean," she sported a blue dress.
She has a different appearance in the book Mother Knows Best. She wears a pink dress, lipstick, and no glasses, and looks about the same age as her son.
Betsy Krabs is generally shown to be nice and caring, as she is shown to love her son and was nice to SpongeBob and Patrick when meeting them for the first time. In addition, she does not share her son’s greedy tendencies.
However, she can get temperamental whenever she is messed with, like when Mr. Krabs raided her dresser and Plankton deceived her in the name of getting the formula. She was also shown in the crowd cheering for SpongeBob and Patrick's violent fate in "Spongicus."
She is also not afraid to punish Mr. Krabs like a child well into his adulthood, as seen when she sends him to his room for stealing her panties.
The two had two children, Eugene H. Krabs, who was born on November 30, 1942, and an unnamed daughter, born either before or after Eugene's birth.
At some point, her father-in-law took custody of her son while he was an infant. Though in the events of "Friend or Foe," Eugene is seen living with her again.
Role in series
SpongeBob and Patrick are forced to re-paint her house as punishment for swearing. Since the two have been doing a good job, Betsy rewards the duo with a glass of lemonade, but spills them upon tripping over a rock, after which she expresses anger over her pain and censorship sounds are heard that imply that she herself is swearing, although these sound effects are then just revealed to be the honking of Old Man Jenkins' jalopy.
SpongeBob, Patrick, and Mr. Krabs break into a woman's house at night to steal her undergarments as part of the promised "panty raid." The gloves come off the moment that the woman they raided is revealed to be Mr. Krabs' mother, initially unbeknownst to the trio. Betsy catches them in the act as she turns on the light. Disgusted by her son's malicious actions, she sends him to his room for the rest of the night.
Betsy plays her first major role in this episode. Plankton develops a crush on her due to her elderly appearance and schedules a date with her at the Krusty Krab. It then appears as though Plankton uses the fist of one of his robots to break through her house and take her to destroy Bikini Bottom, although this is just revealed to be an arcade game simulation.
They then go on a date, although things get iffy as it is revealed that Betsy's date is Plankton. Mr. Krabs calls his mother out for associating herself with his arch-nemesis, but Betsy ignores him and is about to propose a marriage to Plankton. At that moment, when it is revealed that Plankton was just using her to get the secret formula, Betsy automatically loses her interest in him and turns her back against him.
"Friend or Foe"
She appears in the flashbacks of Mr. Krabs as a baby.
Betsy appears at the Krusty Krab and later she is seen in the crowd begging for SpongeBob and Patrick to get mauled by the lion fish.
"Lame and Fortune"
She is seen in the dream sequence attending Mr. Krabs' funeral.
She has not made a speaking appearance in over a decade since "Spongicus."
Mama Krabs has a laugh strikingly similar to Popeye.
In the episodes "Sailor Mouth" and "Mid-Life Crustacean," Betsy's voice sounds like an old woman version of Mr. Krabs while played by Tibbitt, while in the episodes "Enemy In-Law," "Spongicus," and "Friend or Foe," she has a younger Scottish voice while portrayed by Irwin.
It is shown in the episode "Enemy In-Law" she has large muscles after she learns that Plankton tricked her to get the Krabby Patty secret formula.