Question

are microscopic marine
plants which are vital for balancing the ecosystem.
They provide food for a wide range of sea creatures like whales, jellyfish, etc. Most of its species are single-celled marine plants that live through photosynthesis, much like terrestrial plants​

Answer 1

Plankton is the term that marine scientists use to define organisms (animals, algae or bacteria) which float in the water and drift on the oceanic currents. Usually they are microscopic, which is why we do not see them unless we have a magnifier or a microscope.