The base of marine life is a large complex group of organisms known as plankton . Although some plankton can swim, their ability to is generally less than the strength of water movement. Plankton include a wide variety of organisms such as algae, bacteria, single-celled animals.
Phytoplankton carry out photosynthesis and are the base of the food chain in the ocean.
Zooplankton are heterotrophic consumers. Bacteria decompose organic matter into its non-living constituents. Below we focus on the key phytoplankton groups that contribute to ocean color. These algae occur as single cells, chains and colonies. Cell sizes range from 5 to 1000 micrometers.