Surprising Sharks by Nicola Davies, illustrated by James Croft

From the back of the book:
What's the last word you want to hear when you're swimming in the warm blue sea? "SHAAAAAAAARK!" But most sharks aren't at all what you would expect. In fact, if you thought all sharks were giant, man-eating killers, you're in for a big surprise. Sharks come in all shapes and sizes-and probably should be more afraid of humans than we are of them.