Mermaids

The mermaids are five teenage girls who used to live in the Bikini Bottom Triangle. They used their singing voices to summon many objects from Bikini Bottom. They all first appear in the episode "Welcome to the Bikini Bottom Triangle," and the purple-haired mermaid and the blue-haired one also appear in "Mermaid Man Begins."

Ginnifer Goodwin voices the lead purple mermaid, Lori Alan voices the red-haired yellow mermaid, Jill Talley voices the light blue and dark blue mermaids, and Sirena Irwin voices the dark purple-haired mermaid.

Description
There are five mermaids in total. They all look similar to each other, apart from their hair and tails. There is a red-haired mermaid with a teal-colored tail, a blue-haired mermaid with an aqua colored tail, a black-haired mermaid with a green colored tail, a purple-haired mermaid with a lime-green colored tail, and lastly a blonde-haired mermaid with a lighter green tail.

Personality
They have personalities of stereotypical bratty teenage girls and feel no obligation in returning stolen items.

"Welcome to the Bikini Bottom Triangle"
The mermaids are first seen stealing in Bikini Bottom from their singing. Their reason for stealing the objects is so they can find something "cool" to wear. is revealed to have a crush on the mermaids but they are somewhat confused seeing Patrick when he wants to hang out with them.

Later on, they reject him by throwing him onto for annoying them. They are then confused by 's rants of wanting to go to the mall and asks her what a mall is before getting excited over her explanation of it. They then decide to go with her to see it for themselves and sing their song backwards, after suggests it. Doing so returns the enormous pile of the stolen objects back to Bikini Bottom.

Once the items are back, they become friends with Pearl and go to the mall with her.

"Mermaid Man Begins"
Mermaid Man's version of his backstory includes the lead mermaid. She saves him from drowning and gives him a magic sea star that allows him to breathe underwater. The blue-haired mermaid helps too.

Legends of Bikini Bottom (game)
The mermaids are the main focus of the mini-game "Suction Destruction." They prepare their giant vacuum to take everything in their path. SpongeBob dodges the vacuum's debris and throws TNT barrels at it. At the end of each level, SpongeBob has to dodge the mermaids' music notes.

SpongeBob Comics No. 16
In the story The Treasure of Captain Goldfish, the blue and blonde-haired mermaids appear along with a green mermaid on a rock near Goo Lagoon.

SpongeBob Comics No. 23
The purple mermaid appears on the included poster.

Trivia

 * Like Princess Mindy, Patrick has a crush on them because he loves mermaids.
 * They are also seen on the cover of the Legends of Bikini Bottom DVD.
 * One poster shows SpongeBob and Patrick going into a cave where they find a picture of the purple lead mermaid, Madame Hagfish, and Ma Angler on the cave walls.
 * The dark blue mermaid resembles Queen Amphitrite.