How do fish survive in deep sea and why do they die when you take them to water higher up?
In: Biology
Fish have what is known as swim bladders. These are the same in principle as the ballast tanks on submarines. They fill these with water to control their buoyancy. But unlike submarines they cannot just blow all the water out so a deep sea (deep water, probably applies to deep lakes too) fish that is pulled rapidly up has the water in these bladders expand to the point that they burst. Besides it probably being painful the fish cannot regulate its buoyancy and will flay and flounder in the water till it dies or is eaten.
As for survival they are simply made to be able to withstand the greater pressures. It helps to be filled with water and cartilage instead of giant gas bags and rigid bones like we have, we simply don’t compress very well. That is why for a while the navy was experimenting with an oxygen emulsion for deep divers to breath, similar to the amniotic fluid that we all breathe for 9 months.
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