I'm having troubles with developing my ocean world. Same size as Earth, same atmosphere and gravity.

The idea is that on a planet with an endless ocean with no continental landmass. The only form of dry land is floating islands. Heres what they could look like. enter image description here

They're mostly made of a concrete type of material. Probably enchanted. (This is a fantasy world btw.)

Their origins are mysterious. But I was wondering what life could evolve from it. I was thinking of life was connected to the ocean. The marine life in this world is similar to the Cambrian, Ordovician and Silurian period.

Maybe a Devonian period had happened. Also if some organism develope intelligence, how would that affect them?

All ideas and suggestions are welcome.


closed as too broad by Renan, Don Qualm, RonJohn, Alex2006, L.Dutch Mar 10 at 11:30

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ Remove the question about civilizations and narrow it down to intelligent life. As it's stated now all life is simply to broad for this format. If you have additional questions remaining ask them in new questions. Posting multiple separate questions is fine in this format. Also additional questions, do we get an ozone layer? Any plantlife? Gravity is earthlike? $\endgroup$ – Mormacil Mar 9 at 21:28
  • $\begingroup$ Welcome to the site Borbman, please take the tour and read up in our help centre about how we work: How to Ask You pre-empted the rest of my comment with your edit. That being said We need to be able to identify a single best answer to aim for, you've lefti it very open - perhaps specifying a single organism and it's specific environment and the pressures it's subject to to adapt over evolutionary time ... We need more info. $\endgroup$ – Don Qualm Mar 9 at 21:41
  • $\begingroup$ Why couldn't the islands be natural? If animals like the chambered nautilus formed colonies, their shells could aggregate into a thing somewhat like a floating reef. $\endgroup$ – A. I. Breveleri Mar 10 at 1:37
  • $\begingroup$ That's not a bad idea! $\endgroup$ – Borbman Mar 10 at 1:50

Could sapient life evolve on an ocean world? Sure

So long as your ocean is rich in organic life, has heat sources (such as volcanic vents) and mineral access, it's completely believable that sapient life would evolve on an ocean world. Such a creature would develop the ability to move freely in water, breathe and see in water and low-light conditions, and evolve the ability to manipulate its world.

Could sapient life evolve to take advantage of artificial floating islands? Well...

The problem with artificial floating islands is the word artificial. Evolution takes a honking long time — and those islands need to be there and be maintained during all that time. Like, millions of years worth of time.

Worse, sapience comes before artificial, not the other way around. This means if you do have AFIs (Artificial Floating....), someone else not of that world built them and is maintaining them.

But could sapient life evolve on an ocean world and then build AFIs?

Yes, but think about that. We evolved away from oceans onto land. We're no longer engineered to go back. That means we must construct artificial environments (think "domed underwater cities") to live in the water again. Your ocean-evolved creatures, having never had land to evolve onto, would face the same problem. No water to breathe. That makes this explanation kind of a tough nut to swallow, so to speak. What's the point of building a floating fish tank? Now, if there was dry land, building an fish tank on that dry land just as we would a terrarium underwater, that would make sense.


You're developing a fantasy world with magic. You have the privilege of simply declaring the situation to be true. I'd stick with that, because unless you are bringing a third party into the story (the AFI builders) and then allowing magic to change your ocean-evolved dwellers such that they can breathe air (in a way superior to whales and dolphins1), there is no science-worthy explanation for what you want to do.

1Seals, walruses, etc., don't count in this analysis. Think of them as half-way through the process of evolving away from the ocean. They had land to begin evolving onto. Yes, you could do that — but as I explained, that requires a third party building and maintaining the AFIs for millions of years while your ocean-evolved folks figure out how to breathe air and manipulate rocks and trees long-term.

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    $\begingroup$ Well, I was thinking maybe the original inhabitants of the AFI's died out or just left. The AFI's are just left abandoned, maybe some of the plant life could and animals, which most likely be bugs (ants, beetles, worms, etc) could evolve. Maybe crustaceans and cephalopods find them as a food source? $\endgroup$ – Borbman Mar 9 at 22:53
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    $\begingroup$ @Borbman, From a story perspective, sure! You're simply declaring that the artificial nature of the islands is indestructible (capable of lasting millions of years). Frankly, you could have some fun with that idea. AFIs may not come in sight of one another for a bazzillion years, which means some have unique ecosystems, others have surprising similarities, and some were destroyed when an intruding something destroyed the ecosystem. If they're around that long, then seals, etc., do have the chance to evolve onto them. Why not? $\endgroup$ – JBH Mar 9 at 23:25
  • $\begingroup$ Actually there are strong suspect that an ocean world would be a terrible place for life: lacking phosphorus washed away from dry land, plants would have a hard time developing. And without plants goodbye life. $\endgroup$ – L.Dutch Mar 10 at 5:08
  • $\begingroup$ @Borbman, while I'm honored to have my answer accepted, let me recommend that you uncheck it and let it ride for a day. We have participants all over the world and human nature is to skip questions that have an accepted answer. $\endgroup$ – JBH Mar 10 at 5:29
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    $\begingroup$ @L.Dutch, yes and no. Phosphorus isn't unique to dry land. An ocean planet would need a fair amount of underwater volcanism to make up the difference. I'll grant you that it would seem to be less likely (although that'll probably change the first Goldilocks ocean planet we discover, science is funny that way). $\endgroup$ – JBH Mar 10 at 5:31

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