Drifting ocean animals - from teeny specks to big drifters like jellyfish and salps. “Plankton” means drifter, so they ride the currents more than they swim. Some are babies of bigger animals (like crab or fish larvae); many are see-through or spiky to stay safe. They snack on phytoplankton and smaller zooplankton.

Why it matters: Zooplankton are in the middle of the ocean's food web - they feed fish, seabirds, turtles, and whales. As they eat and poop (and when they sink), they send carbon down to the deep sea, which helps Earth’s climate.

Fun fact: They migrate up at night and down by day, the biggest daily commute on Earth.

Say it like this: ZOH-uh-PLANK-tuhn

Your turn: Play “Zooplankton Tag”: crouch (day, deep), then pop up and “drift” (night, surface)!

To find out more, download our infographic about plankton sizes