Trouble at Sea

 is the thirty-sixth episode of the first season of Star Teens Unite!.

Summary
The Star Teens head off to sea at Arco Iris to save Nemo's older sisters from a mutant crab pirate named Captain Birgus and his mutant pirates.

Debuts

 * Captain Birgus and his mutant pirates
 * Nemo's sisters

Characters

 * Ella
 * Inidra
 * Sandra
 * Felicia
 * Lisa
 * Tanya
 * Sheila
 * Bella
 * Veronica
 * Ms. Diana Apple
 * Principal George Thompson
 * Nemo
 * Mermaids
 * Captain Birgus and his Mutant Pirates

Voice Cast

 * Aimee Carrero - Tanya
 * Ariel Winter - Nemo
 * Candi Milo - Ms. Diana Apple, Nemo's Sister #6
 * Cree Summer - Nemo's Sister #7
 * Dee Bradley Baker - Lobster Mutant Pirate
 * Grey Griffin - Sandra, Nemo's Sister #1
 * Jeff Bennett - Shark Mutant Pirate
 * Jennifer Hale - Veronica, Nemo's Sister #2
 * Kari Wahlgren - Ella, Nemo's Sister #4
 * Kate Micucci - Inidra
 * Kath Soucie - Nemo's Sister #3
 * Keith Ferguson - Walrus Mutant Pirate
 * Kimberly Brooks - Sheila
 * Mark Hamill - Captain Birgus
 * Rob Paulsen - Octopus Mutant Pirate
 * Ron Perlman - Principal George Thompson
 * Susanne Blakeslee - Bella
 * Tara Strong - Felicia, Nemo's Sister #5
 * Vyvan Pham - Lisa

Trivia

 * Captain Birgus is a reference of Birgus latro, the scientific name for coconut crab, one of the largest living terrestrial arthropods.
 * Although unnamed, other mutant pirates include a great white shark, a walrus, an American lobster, and a giant Pacific octopus.
 * Unlike Nemo, her mermaid sisters are 16 years old and they are voiced by Grey Delisle Griffin, Jennifer Hale, Kath Soucie, Kari Wahlgren, Tara Strong, Candi Milo, and Cree Summer, whom these mermaids resemble teen versions of.