WHAT ARE PLANKTON?
Drifting through the world’s waters are tiny organisms that feed fish and trap carbon
In seawater worldwide, microscopic organisms called plankton are bobbing along with the current. Plankton are vital for maintaining balance, not only in marine ecosystems, but also in regulating the global climate. Plankton can be divided into two different categories: phytoplankton and zooplankton. Phytoplankton, also known as microalgae, are chlorophyll-packed organisms that operate in the ocean in a similar way to how plants live on land. To obtain their food and energy, phytoplankton perform photosynthesis. These tiny invertebrates convert sunlight and carbon dioxide dissolved in the water into energy, releasing oxygen as a byproduct.
Their requirement for sunlight means that plumes of phytoplankton are found drifting near the surface, moving around the world at the mercy of ocean currents.
Zooplankton, on the other hand, are microscopic organisms made up of many different animals, including fish larvae, worms and even snails. One of the best-known creatures categorised under the zooplankton umbrella is krill. As the preferred meal of many penguin and fish species, along with the world’s largest animal, the blue whale
(Balaenoptera musculus), krill, and all other zooplankton, serve as an important food source in marine ecosystems.
Another way that plankton play a vital ecological role is within Earth’s global carbon cycle. As a carbon sink, the ocean is one of the many places where carbon is plucked from the atmosphere and stored. Plankton act as a kind of carbon conveyor belt, moving different forms of this chemical element from the surface and transforming it through various means, such as by defecating or dying, in a process known as the biological carbon pump. Phytoplankton transform carbon dioxide that has dissolved into seawater through photosynthesis into organic carbon to build their bodies and