"Kitana, a self-proclaimed Shark Princess, and her best friend Mack go on an underwater adventure in an abandoned shipwreck" (description from publisher)
With the help of Star, Narwhal, who is now a Narwhalicorn, and Jelly embark on an out-of-this-world adventure to a planet filled with unicorns, but when Jelly wishes he were back home, Narwhal must find a way to cheer him up. - Published from Catalog
Shark Princess by 
Narwhalicorn and Jelly (a Narwhal and Jelly Book #7) by 
Super Magic Boy: I Am a Dinosaur by