Frank the whale

Frank the whale is a blue whale who first appears in the episode "Ripped Pants."

Description
He is a black blue whale with a pale gray underside. He wears green swim trunks in "Ripped Pants," and orange swim trunks in "SpongeBob's Big Birthday Blowout." In some episodes, he wears a business suit with a hat. In "You Don't Know Sponge," his wears a light olive green and dark green suit, red tie, and a small light brown hat with a red stripe. In "Mutiny on the Krusty," he wears a blue suit, and a light brown tie and hat with a black stripe. In "Slimy Dancing" and "What Ever Happened to SpongeBob?," he appears as a female character. The female version of Frank is a ballerina who wears a pink tutu and light green shorts.

"Ripped Pants"
After rips his pants off and realizes the mistakes he made, he asks himself if he is the bigger loser on the beach. Frank pops up from underneath the sand and reveals that he was buried in the sand and forgotten to prove him wrong out of sympathy. He, along with Incidental 22 and the loser, sing the "Ripped Pants" song with SpongeBob. Frank plays the drums during the song. At the end, he and the other band members rip their pants just like SpongeBob.

"Slimy Dancing"
Appears as a female. She is one of the contestants in the Bikini Bottom Dance-A-Thon, where her act is balancing a beach ball on her head while balancing on her right flipper. She gets a total score of 23.5 from the judges.

"What Ever Happened to SpongeBob?"
Appears as a female. She briefly appears in the crowd when SpongeBob is elected mayor of New Kelp City.

"You Don't Know Sponge"
When he hears making whale sounds, he thinks it is his ex-wife, Martha, calling him until his friend assures him it is not.

"Mutiny on the Krusty"
He is one of the things in the severe rip current.

"SpongeBob's Big Birthday Blowout"
He is one of the many guests seen at SpongeBob's birthday party. He is later seen singing "happy birthday" at the end with SpongeBob's friends and family.

Trivia

 * He and his ex-wife, Martha, are the only known blue whales in the series.