Water in living things and food

Water content varies widely across species and depends on which tissue is measured. For fish flesh, FAO gives typical values of about 80% for lean fish and 70% for fatty fish; that should not be generalized to all animals. Jellyfish are about 95% water. For raw produce, USDA data per 100 g give 85.56 g for an apple with skin, 94.52 g for a red tomato, and about 79 g for a potato with skin. Thus the frequently repeated figures of 99%, 76%, and 90% for these examples need correction, and exact values vary by sample and variety. [1–4]