- Mar 8, 2004
Fujisawas Sake said:Another point; osmoregulation. Cephs don't handle freshwater. They are by their nature isosmotic with the seawater and freshwater would stun and most likely kill a ceph quickly. Their metanephridia are no where near as hardy as our kidneys, which are pretty fragile. Fish are better at taking the extremes of freshwater by highly developed kidneys. Very few molluscs are freshwater, and those that are show signs of having returned to the water from a land-based life (pulmonate gastropods).
wasn't the ocean salinity a lot lower when molluscs first arose, though? It seems more plausible that there is genetic leftover that could be reverted to as a pretty simple mutation that could allow them to live in freshwater environments...