Physiology of Finfish and Shellfish (2+1)

1.2.6. The Biological importance of water as a solvent and as a medium for living organisms

Water is possibly, the most important substance to life in order to survive; it also provides an environment for many species. All cells contain a minimum of 85% of water, with most fluids inside and outside of the cell likely to have at least 90% water. Both transportation of molecules and chemical reactions take place in dissolved water. In chemical terms, the water molecule is strongly dipolar, this property makes water a very effective solvent, particularly for crystalline salts .So, water is the solvent of the body & it regulates all functions, including the activity of everything it dissolves & circulates.

Water is the medium in which all chemical reactions in the body take place. blood, which contains 80% water, is vital in transporting oxygen to the tissues and carbon dioxide from the tissues as well as being the life support system for the body. In its major functions, water acts as:

• an ideal lubricant to transport feed;
• an aid in excretion;
• a regulator of body temperature; and
• A buffering agent to regulate pH of body fluids.