what is the evolutionary way leading to gemulated sponges in fresh waters?why?

Question

gemulated sponges are mainly found in fresh waters,but there are some in seas.what is the evolutionary pathway leading to this:
\1)there were sponges became gemulated in fresh waters,then migrated to the seas./or
2)there were sponges gemulated in the seas and only this kind of sponges could live in freshwaters,so fresh waters just contain this kind.
p.s.the spelling of gemul may be wrong.sorry

Answer 1

Way 2.
What was most likely to have happened is the sponges were living near a fresh water river that emptied into the ocean and over time adapted to being able to live in less and less salty conditions and eventually were able to survive in fresh water.