A question about the origin of earths water

[JaredCBell]

This doesnt really relate too much to aquariums but in a way it does and I am trying to prove a point to my brother and I believe you people, with your extensive knowledge of both marine and freshwater fish, will help with that.

He (along with many Scientists) believe that the earth was once all freshwater. I believe this to be impossible because of the certain species of fish (and mammals) that could basically only live in marine water and by evidence thats what they were designed for.

Now, without getting into a creation and evolution debate, he is on the side of creation so to him, there is no possibility of evolution, just adaptation. Which I also believe but I want to prove a single point that marine fish were designed for marine water and vise versa....It couldnt have been all freshwater and then slowly they starting adapting to where they could only live in salt water.

Make sense? I tried using examples of fish and inverts that are ONLY found in freshwater so to say that they came from nowhere would then start supporting evolution and would then debunk his whole argument. I just dont have too much knowledge on marine fish.

Sorry my argument points are all over the place I just want to know what I can throw at him to help support my theory.

Now if you all believe that the earth was all freshwater, then I am screwed... thumbs2:

*Other reason I am doing this is because he is going to try and prove that a GSP can live fully in freshwater. Thats how this whole argument started. Im trying to tell him, it wont.*

[Fishguy2727]

Honestly (without being rude) if you do not believe in evolution (the unifying theory of all sciences) I can't really give you any scientific facts that you could believe while denying evolution and the sciences that support it. I will give you the general basic explanation, if you do not believe it that is your business. (Please don't take this the wrong way.)

The salt from the oceans was put there slowly over time by freshwater running off the continents and into the ocean. On their way they dissolve minerals (in rocks and soils) which then made their way to the oceans with that freshwater. So yes, the oceans were once all freshwater. Some support for this is found in land-locked lakes (that do not drain into the ocean) that have water much harder than freshwater and very low salinities (like the Great Rift lakes in Africa). Since they are much younger than the oceans (hundreds of thousands of years as opposed to billions) it makes since that the salinity is so low in them, but still notably higher than 'normal' freshwater.

With the salinity of the oceans increasing so slowly its inhabitants would evolve adaptations to deal with this.

If the animals he wants to keep are naturally found in brackish, he needs to keep them in brackish. They may do 'very well' or 'fine' for a while, but you can pretty much guarantee they won't thrive long-term.

[JaredCBell]

no you proved my point. im trying to show him that his theory supports evolution. which he doesnt believe in.... it also supports old earth theory. we both believe in creation he is just trying to explain the flood and why it didnt kill off all the fresh water fish by having the ocean mixed with lakes and vice versa. thank you!

[Lady Hobbs]

Interesting topic. According to this article, saltwater fish learned to live as freshwater fish, as well, with changing of the earth and oceans being blocked.

Not your original question but interesting.

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[gourami*girl]

Very interesting article Lady Hobbs, thank you for posting it!

As far as the GSP living happily in fresh water because they evolved from freshwater fish, the reasoning isn't quite sound. If each individual went from brackish to fresh on a regular basis, it might be possible, but as far as I know GSP are from an entirely brackish environment. By the same reasoning, since I evolved from a fish, I might be happy to live in an entirely underwater environment, but this is surely not the case, lol!

[Gemini]

Wow Jared dinner time at your place must consist of some interesting debates!