WATER CONTENT. “The percentage of water in the protoplasm of an organism depends directly on the age, habitat and metabolic activities. For example, the cells of the embryo have 90 to 95% water which decreases progressively in the cells of adult organism. Aquatic lower animal cells possess more water than the cells of higher terrestrial animals.”
http://www.yourarticlelibrary.com/biology/protoplasm-physical-and-chemical-nature-of-protoplasm-biology/5147