At first glance, Rita seems to be the totally normal land person. But she has a secret: she's actually a mermaid. When she was younger, Rita swam with the pod off Mako Island. But she fell in love with a land person, Harry. She used to sneak off and get legs to spend time with him- until the pod discovered what she was up to. She became a pariah. So Rita made the decision to leave the pod and forged a life for herself with Harry among the land people.
Although Harry passed away, Rita has been successful on land and is now the principal of the local high school. She has survived and protected her true identity by keeping a somewhat cool and distant outer image.
Although a bit lonely sometimes, Rita has more or less adapted to her life.
That is until three young mermaids turn up and ask for help. Rita is torn- she gave up mermaid life, and she doesn't want three reckless young mermaids blowing her cover, but Rita can't turn them away. As she becomes their mermaid mentor and guide, Rita discovers that although there are complications, the mermaids bring companionship and laughter back into her life. Though she truly loved being a mermaid, she still refused Lyla's offer to return home and become one of the pod again, stating that her life now was on land.
Rita's usual role is to provide knowledge and wisdom on magic whenever the merpeople need it and does not usually get involved in their adventures. The one exception is in "Reunion" when her ex friend at the time Verida, reveals her intentions to deal with Zac personally when she learns he has unlocked a merman chamber. Fearing for Zac's life, Rita follows her and threatens Veridia with her own powers when she nearly attacks Zac. Rita and Veridia make amends after Veridia realizes that Rita was right about Zac being a friend and that some land people can be trusted, even agreeing with her when Rita expresses hope that one day the world of land and sea will become one.
In season 3, Rita quit her job as Principal of Suncoast High and decided to go back to the pod. Now Rita teaches at mermaid school, replacing Ondina in her position while maintaining residence on land.
Rita possesses the ability to transform into a mermaid ten seconds after direct physical contact with water. She turns back into a human a few minutes after she is out of the water and when the water on her has fully dried. Once her body is completely dry, her human form reverts back to what she appeared to be before her mermaid transformation. As a mermaid, Rita has the ability to swim at super speed of 600km/h, hold her breath for more than fifteen minutes, and dive at a depth lower than any ordinary human being.
Aside from these abilities, she is vastly skilled with magic, and has even invented methods of her own.
Rita used this ability to make herself invisible to avoid any of her students learning that she was a mermaid.
When teaching the girls how to control and manipulate various elemental aspects of the weather in "Battlelines", she uses this power to make a miniature tornado in a jar. This indicates that she may be able to control the elements of water, air and electricity in unison.
When teaching the girls how to control the weather in "Battlelines", she uses this extremely powerful and dangerous ability when she made a lightning storm in a jar.
Rita once used this ability to shrink a lemon by draining out the remaining liquids inside.
Rita used this ability to form a water ball while teaching a group of four mermaids to tap into their powers. She also manipulated the water ball to make it explode and produce fireworks.
Rita speaks Dolphin.
- Rita is a shortened version of the name "Margarita", meaning "pearl" in several languages including Persian, Sanskrit, and Latin.
- She has a pet cat named Poseidon.
- Harry died before they got married as revealed in "Lyla Alone", although it is unknown how Harry died.
- Rita is the only mermaid seen using the power to reveal invisible merpeople.
- Rita wears tortoiseshell jewelry as revealed in "Close Call."
- Rita loves lobster and seafood.
- Rita doesn't want to go back to the pod, however, by the end of season 3 she quits her job and goes back to the pod, while also maintaining her residence on land.
- Rita becomes the teacher of the hatchlings in Mermaid School after Ondina gave up her job.
- Rita is often seen wearing a seahorse necklace.
- Rita was in mermaid school with Veridia and was top of the class.
- Rita wrote a thesis on dolphins.
- It seemed that she and Veridia were very close before Rita left the pod, as stated in the episode "Stay or Go."
- She seemed have made her own potion for mermaids to cure the common cold.
- She is the only mermaid present on the entire show.
- Main article: Rita Santos/Gallery