Mermaid Echo is doing tail flips because she's going to see her favorite under-the-sea band, the Rays. They're performing for Pearl's birthday party and everyone at Trident Academy is invited except Echo's best friend Shelly.

A shark has been spotted in Trident City! Pearl Swamp is so scared, she needs a shark Guard to escort her to and from school. She doesn't trust anyone who likes these terrifying creatures, especially Kiki Coral, who isn't nearly as frightened as Pearl. And to make matters worse, Pearl accuses Kiki of stealing her precious pearl necklace! Will the sharks destroy the peace of their sparking city? Or will the mergirls have to swim in dangerous deep-sea...

Of all the creatures in the ocean, sea horses are Echo Reef's favorite. They're sweet and gentle and they glide through the water so gracefully. When Echo discovers that Rocky Ridge, one of her Trident Academy classmates, has his own pet sea horse, she wants one right away. Not everyone agrees sea horses should be pets, however. Perhaps they are happiest when swimming freely. But Echo thinks that if Rocky can make a sea horse happy, she can too! Can't...

While preparing for a unit on storytelling, the mermaids of Trident Academy learn of a legendary pirate treasure in their own city and Pearl decides to find it, despite a warning that it is guarded by a ghost.

When Echo's big sister Crystal takes the sparkling human object that Echo found near her shell, Echo is one mad mermaid. How far is Echo willing to go to get her find back, and can the sisters set aside their squabbles and learn to be friends?

"Pearl has always dreamed of being famous: the star-studded stage, the sea flowers, the applause! So when she finds out that her third grade class is performing The Little Human, she just knows she ll get the leading role. Especially since world-renowned merstar Angelfish Molie is judging the tryouts! But in a shocking turn of events, Pearl s best friend, Wanda, gets cast as the little human instead and Pearl is stuck playing the stinky sea witch....

When Echo injures her tail, she can't compete in the Poseidon Tail Flippers team competition. Will Echo find a way to help her team win from the sidelines?

Unable to comprehend a beloved librarian's imminent marriage to a cafeteria worker who seems to be perpetually grouchy, Pearl becomes jealous when Echo, Shelly, and Kiki are all asked to be flower girls.

Listening to her aunt's story about a fairy that visits mermaids while they sleep to purposely tangle their hair, Echo resolves to catch the fairy in the act before her skeptical friends ask her to figure out whether or not fairies are even real.

Pearl Swamp is not happy when her selection as the next winter princess is overshadowed by her family's decision to adopt a baby boy

Echo's third grade class visit the Titanic and figure out a way of including their new classmate, Anita, who is confined to a wheeled chair.