Illustrating a Map

I am working on sketches for an old fashioned world map that I'll be painting on a client's wall.  These are the basic drawings that I've done for some of the decorative elements.  It's curious...I've had it pounded into me by some artist friends that I NEED a reference pic for all my drawings and paintings, but getting a reference pic of a sea serpent is...a stretch!  Basically you can draw from a snake...or you can copy another artist's work (which is really un-cool)...or you end up just drawing from your imagination.  Which is what I did.  It's the same story with the North Wind and the sun.

After all, if a reference pic isn't available, what is one to do?