Marine biology is defined as the study of living organisms present in the sea along. It includes their interaction with nature and their behavior.
R.H. Whittaker classified all the living organisms in five kingdoms in 1969. He called Protists to the organisms that were eukaryotic but were made up of single cell only. Protists are considered to be the first ever eukaryotic forms of life on Earth. Eukaryotes have the cells which contain membrane bound organelles.