Those would be similar to space whales, which, oddly, Star Wars seems to be unusually lacking in. (Apart from a few odd and obscure things in the Extended Universe.)

Transcript

{opening splash graphic of Obi-Wan's ship arriving}
GM: You're greeted at the landing platform by Taun We, a native of Kamino.
Sally: Ooh, a giraffe alien! I'm playing her!
GM: Uh, okay Sally.
Taun We: Welcome to Kamino, Master Jedi.
Obi-Wan: Nice planet you have here.
Taun We: Yes, the ocean covers everything.
GM: It does?
Taun We: All our cities are on stilts.
GM: Er...
Taun We: Be careful of the flying whales.