What is the fastest animal in the world? What can dive as deep as a whale or make a submarine disappear in the ocean? The answer is zooplankton! The ocean is teeming with these small, drifting animals that come in all shapes ands sizes, from tiny zippy copepods to large, brilliantly colored jellyfish (that you don't want to bump into). There are some very strange zooplankton, like the arrow worm -- you can see what it had for lunch inside...