A millibar is a unit of pressure which is most commonly seen in the context of meteorology, where atmospheric pressure is sometimes given in millibars. As the name would suggest, a millibar is equal to one thousandth of a bar.
User: The microscopic organisms at the base of the marine food chain are known as A. plant life. B. terrestrial animals. C. primitive life. D. phytoplankton. Weegy: The microscopic organisms at the base of the marine food chain are known as Phytoplankton. User: In addition to being necessary for respiration, _______ also provides UV radiation protection. A. water B. hydrogen C. oxygen D. carbon dioxide.
At both poles, tiny animals, called zooplankton, are near the base of the food chain. They eat the photosynthesizing phytoplankton and in turn are food for fish, seabirds and marine mammals. In the Southern Ocean, Antarctic krill swim in dense schools of 20,000 animals per cubic yard (540,000 cubic feet).