When crustaceans such as crabs are kept in seawater with a lower-than-normal pH, ATP-requiring pumps that maintain ion gradients in the animals' bodies significantly increase their activity in comparison with normal levels. Explain how the increased use of ATP by these pumps will most likely affect the ability of the animals to carry out other metabolic reactions such as that catalyzed by PFK. Hemolymph is the fluid in the red king crabs body that surrounds its cells and is typically slightly hypertonic to the seawater in which the crabs live. When adult crabs were removed from their native environment and placed into seawater solutions with gradually decreasing salt concentrations, their body weight increased. Explain how the crabs gained weight during this procedure.