Zima is a shermaid (shark + mermaid). Below is her bio:

In the expansive ecosystem that is the ocean, Zima made a life for herself doing whatever it is she wanted whenever she wanted. Raising herself, she acts on raw instinct and only has two goals in mind: filling her belly and doing something fun. Her lack of manners and complete disregard for social code makes her off-putting to most people, even other merfolk.