Space Invaders (Shark School, Bk. 10)

Harry Hammer's latest hero, terranaut Buzz Sharkfin, is planning a mission to outer space, which to a shark is planet Earth! Harry and his lifelong frenemy Rick Reef are chosen for Buzz's daring mission, but daring turns dangerous when the guys come fin-to-fin with dogs, cars, and - yikes! - humans in this strange and wacky new world.