Fish are cold blooded. That means that their bodies don’t need to generate heat to maintain a high body temperature. Therefore, the oxygen dissolved in water is enough to sustain them. Warm blooded sea creatures like whales and seals all need to breathe air. Air is about 20% oxygen, but water is mostly just water.
A while back, I did the math on how soluable oxygen was in water, and how much water you’d have to process to gather enough oxygen to support a human being, and it was a lot to ask for a self contained deal that you could strap on your back.
Latest Answers