Phytoplankton blooms in the Barents Sea, shown in natural color from NASA's Aqua satellite on July 10, 2014. The solid white area in the top right corner is cloud cover. Credit: NASA's Earth Observatory

What are plankton?

The word “plankton” comes from the Greek for “drifter” or “wanderer.” An organism is considered plankton if it is carried by tides and currents, and cannot swim well enough to move against these forces. Some plankton drift this way for their entire life cycle. Others are only classified as plankton when they are young, but they eventually grow large enough to swim against the currents.

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