<em><u>An estuary is a geographical entity where the salty water of ocean mixes with fresh water of river. The resulting water is known as brackish water. The brackish water is not as salty as that of ocean and also the salinity level of water rise and fall regularly.</u></em>
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<em><u>Thus, an organism that is able to live in both salty water and fresh water environment can survive in an estuary.</u></em>
The glucose and the oxygen travel out into the body through the circulatory system to reach cells that need energy. The cells use the glucose and oxygen from the circulatory system for energy production.
