Edible aquatic animals excluding mammals, but including both freshwater and ocean creatures. Seafood includes bony and cartilaginous fishes, crustaceans, mollusks, edible jellyfish, sea turtles, frogs, sea urchins, and sea cucumbers. The roe, or eggs, of some species are eaten as caviar. After cereals, seafood may be mankind's most important food, furnishing about 15% of the world's protein intake. Lean fish is equivalent to beef or poultry in its protein yield (18–25% by weight), but it is much lower in calories. Much seafood is eaten uncooked, either raw, dried, smoked, salted, pickled, or fermented. Otherwise it is cooked whole or cut into steaks, filets, or chunks. It is often used in stews or soups.