What are plankton and why do they matter?
Plankton are microscopic organisms that live in large bodies of water, and these tiny critters have a big impact. Plankton are the foundation of almost every ecosystem in every ocean; the food chain starts with them. All plankton are classified into two types – phytoplankton and zooplankton.
Phytoplankton, or microalgae, are plant-like organisms that live in the upper layers of almost every body of water on the planet. They photosynthesize just like terrestrial plants by absorbing carbon dioxide from their environment and expelling oxygen. Phytoplankton are responsible for half of all photosynthetic activity on the planet. Different species of phytoplankton require different conditions to live, requiring particular nutrients or temperatures to thrive. When conditions are ideal, phytoplankton can multiply rapidly, creating a bloom. These blooms can be small patches on ocean surfaces or huge streaks stretching hundreds of miles.
A photosynthetic bloom that formed off the coast of New Zealand. Photo credit: NASA MODIS, image by Robert Simmon and Jesse Allen