The Little Mercat: Protector of the Ocean

The Little Mercat; Protector of the Sea is the 56th episode of Season 7.

Summary
The Octonauts, Jake, and Sofia are doing a checkup on a part of a reef in the Sparkle Sea to make sure it is stable and healthy, when they notice robotic parrotfish picking off pieces of coral.

Plot
Jake, Kwazii, Sofia, Captain Barnacles, and Peso dive down into the Sparkle Sea and into a coral reef to witness polypus displaying their colors while also checking on the condition of the reef. While talking about the polyps and the role in the coral reef, they see parrotfish picking at some coral to eat algae. However, while they are not looking, a parrotfish controlled by Cruella De Vil's niece, Ivy De Vil, takes a piece of coral and swims to Cruella's submarine. Accompanying Ivy is her aunt Cruella De Vil, who is planning to use the coral for jewelry. They hope to sell the jewelry so he can get rich.

While finishing up the reef checkup, Dashi notices a half cat, half fish among the coral, which Jake and Kwazii say is a mercat. They then see the mercat instantly glide in the water at fast speed and snatch a fish into its mouth, leading Kwazii to name it Sea Wings. The Octonauts are impressed, and Sofia decides to make a Mercat Creature Power Disc. Jake and Kwazii then pretend to be mercats, when they see Ivy's robot fish taking pieces of coral. Sofia finishes the discs and she teleports them to the her friends, who camouflage after activating their Magical Creature Power Suits. They manage glide in and catch a few robotic parrotfish, when Ivy and Cruella arrive to find out why the robotic fish are not returning to their submarine. While Ivy is counting the fish already under her control, Jake and Kwazii see Sea Wings swishing her tail to lure in a parrotfish, and Jake tells Sofia to install a lure attachment. Kwazii makes his first move by casting his lure – a bejeweled hair barrette, towards Ivy, while Jake casts his lure – a piece of coral jewelry, towards Cruella. Cruella and Ivy, mesmerized by the lures and not taking notice of the camouflaged pirates, move closer to them. They instantly take their underwater vehicles. Then Sea Wings takes in Ivy's controller. Sea Wings then hands it into Kwazii's fins. Kwazii deactivates the robotic suits on the parrotfish. Captain Barnacles, Sofia, and Peso head to Cruella's submarine and use a robot arm to grab the net containing the pieces of coral. After Kwazii hands Ivy her controller back, the Kratt brothers spit out Zach and Donita's underwater vehicles, propelling them away. At the end, the Kratt brothers use a special tape to reattach the broken-off corals.