Jonnie is a short shark who is light reddish-gray in color and has blonde hair. He wears a purple tank top and purple tights.
He is only seen in a flashback where Sharkface explains to SpongeBob what happened to him. Jonnie was performing a dance stunt at the Howlin Marlin, but messed up and ended up destroying the floor with his teeth and injuring himself in the process.
Jonnie is the only shark in the gang who has a hair color other than black.
Jonnie may never dance in the Sharks again.
He is a spoof on Johnny from the book The Outsiders by S. E. Hinton.