<p>If the planet is geologically/volcanically active <a href="https://en.wikipedia.org/wiki/Hydrothermal_vent" rel="noreferrer">hydrothermal vents</a> are a way by which nutrients, in the way of minerals and chemicals, can enter the ocean.</p>

<p>Certain types of bacteria can consume the minerals and such bacteria form the base of a food chain. Also, the heat from the hot water can provide energy to life forms.</p>

CC BY-SA 3.0
2018-02-06T01:36:05.573Z
2018-02-06T02:23:13.460Z
2018-02-06T02:23:13.460Z
Fred
<p>On an <a href="https://en.wikipedia.org/wiki/Ocean_planet" rel="nofollow noreferrer">ocean planet</a>, nutrients can come either from space or from the bottom of the ocean, where they can leak from the crust trough different processes, perhaps with the help of submarine volcanoes or hydrotermal vents if the planet is geologically active. The latter is likely to be the case, because assuming you meant water oceans, to have that much water at the right temperature to keep it liquid, the planet will most likely be a <a href="https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Habitable_super-Earths" rel="nofollow noreferrer">super earth</a> orbiting a small star, like <a href="https://en.wikipedia.org/wiki/Kepler-22b" rel="nofollow noreferrer">Kepler-22b</a>
<a href="https://i.sstatic.net/yk6KJ.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/yk6KJ.png" alt="enter image description here"></a></p>

<p>Such large planets will most likely cooldown slow enough to provide many billions of years of volcanic and tectonic activity.</p>

<p>However, from Earth's oceans, we know that the most biologically productive areas are associated to landmasses, because they force upwelling and due to the nutrients that rivers and winds carry from them.
So perhaps more than the original source of the nutrients, we should figure out how those nutrients will cycle to sustain life: In an ocean world, the productivity would be limited by the strength of the ocean vertical currents, that could bring nutrients from the bottom of the ocean to shallow waters were sunlight provides the planet's largest source of energy.</p>

<p>At some point, ocean worlds were very good candidates to host life, but now it looks it might not be the case: Due to the quick dissolution of chemical gradients on an ocean. The leading theory for the origin of life is that of the "<a href="https://blogs.scientificamerican.com/thoughtomics/did-life-evolve-in-a-warm-little-pond/" rel="nofollow noreferrer">warm little pond</a>", an environment that wouldn't exist in an ocean planet.
<a href="https://i.sstatic.net/C3ZWT.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/C3ZWT.png" alt="enter image description here"></a></p>

<p>Another problem facing life on super earth ocean worlds, is that with the pressures found at the bottom of the ocean, the ocean floor will probably get covered in <a href="https://en.wikipedia.org/wiki/Amorphous_ice#High-density_amorphous_ice" rel="nofollow noreferrer">HDA</a> a dense form of water ice. Creating a layer that would difficult the exchange of chemical compounds and heat between the crust/mantle and the ocean, hampering the formation and sustainability of life. On the bright side, if such planets orbit a small star, they will have plenty of time to form life, as small stars live much longer.</p>

<p>So in addition to ask if an ocean world can support life, it is also interesting to ask if life is likely to form in such worlds.</p>

<p>It is a possibility that in such worlds life is confined to hydrotermal vents, but from your question I assume you are pondering the possibility of an ocean full of life, like the ones on Earth.</p>

CC BY-SA 3.0
2018-03-15T07:15:02.413Z
Will shallow oceans  have better nutrient concentrations? Though they may out of luck when it comes to originating life.
Sid Datta
CC BY-SA 3.0
2018-03-15T14:00:58.270Z
@SidDatta Yes they would, and also if there is light reaching the ocean floor, life can flourish right there where the nutrients are, like in coral reefs. However, it is unlikely that and ocean world would be shallow. In such case there would most likely be dry land too.
Camilo Rada
CC BY-SA 3.0
2018-02-07T00:45:00.010Z
2018-02-12T18:26:05.343Z
2018-02-12T18:26:05.343Z
Camilo Rada
<p>On earth nutrients flow from the land to the ocean. Life on oceans need those nutrients to trive.  </p>

<p>I was trying to think how an ocean world might support life if there was no land to provide the necessary bootstapping nutrients.</p>

<p>Any thoughts?</p>

CC BY-SA 3.0
2018-02-06T08:24:17.670Z
this had been a larger problem for life on land,no evaporation of water from the ocean will make the land too dry for life to exsist.
trond hansen
<ocean><oceanography><planetary-science><biogeochemistry>
How would a world entirely covered in oceans get the nutrients to support life?
Todd Hoff
# How would a world entirely covered in oceans get the nutrients to support life?

(Asked by: username_0 on 2018-02-06)

On earth nutrients flow from the land to the ocean. Life on oceans need those nutrients to trive.

I was trying to think how an ocean world might support life if there was no land to provide the necessary bootstapping nutrients.

Any thoughts?

**Tags:** ocean, oceanography, planetary-science, biogeochemistry

> **Comments:**
> **username_1**: this had been a larger problem for life on land,no evaporation of water from the ocean will make the land too dry for life to exsist.  

---

## 2 answers

### Answer by username_2 on 2018-02-06. Score: 7

If the planet is geologically/volcanically active [hydrothermal vents](https://en.wikipedia.org/wiki/Hydrothermal_vent) are a way by which nutrients, in the way of minerals and chemicals, can enter the ocean.

Certain types of bacteria can consume the minerals and such bacteria form the base of a food chain. Also, the heat from the hot water can provide energy to life forms.


---

### Answer by username_3 on 2018-02-07. Score: 6

On an [ocean planet](https://en.wikipedia.org/wiki/Ocean_planet), nutrients can come either from space or from the bottom of the ocean, where they can leak from the crust trough different processes, perhaps with the help of submarine volcanoes or hydrotermal vents if the planet is geologically active. The latter is likely to be the case, because assuming you meant water oceans, to have that much water at the right temperature to keep it liquid, the planet will most likely be a [super earth](https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Habitable_super-Earths) orbiting a small star, like [Kepler-22b](https://en.wikipedia.org/wiki/Kepler-22b)
[![enter image description here](https://i.sstatic.net/yk6KJ.png)](https://i.sstatic.net/yk6KJ.png)

Such large planets will most likely cooldown slow enough to provide many billions of years of volcanic and tectonic activity.

However, from Earth's oceans, we know that the most biologically productive areas are associated to landmasses, because they force upwelling and due to the nutrients that rivers and winds carry from them.
So perhaps more than the original source of the nutrients, we should figure out how those nutrients will cycle to sustain life: In an ocean world, the productivity would be limited by the strength of the ocean vertical currents, that could bring nutrients from the bottom of the ocean to shallow waters were sunlight provides the planet's largest source of energy.

At some point, ocean worlds were very good candidates to host life, but now it looks it might not be the case: Due to the quick dissolution of chemical gradients on an ocean. The leading theory for the origin of life is that of the "[warm little pond](https://blogs.scientificamerican.com/thoughtomics/did-life-evolve-in-a-warm-little-pond/)", an environment that wouldn't exist in an ocean planet.
[![enter image description here](https://i.sstatic.net/C3ZWT.png)](https://i.sstatic.net/C3ZWT.png)

Another problem facing life on super earth ocean worlds, is that with the pressures found at the bottom of the ocean, the ocean floor will probably get covered in [HDA](https://en.wikipedia.org/wiki/Amorphous_ice#High-density_amorphous_ice) a dense form of water ice. Creating a layer that would difficult the exchange of chemical compounds and heat between the crust/mantle and the ocean, hampering the formation and sustainability of life. On the bright side, if such planets orbit a small star, they will have plenty of time to form life, as small stars live much longer.

So in addition to ask if an ocean world can support life, it is also interesting to ask if life is likely to form in such worlds.

It is a possibility that in such worlds life is confined to hydrotermal vents, but from your question I assume you are pondering the possibility of an ocean full of life, like the ones on Earth.

> **Comments:**
> **username_4**: Will shallow oceans  have better nutrient concentrations? Though they may out of luck when it comes to originating life.  
> **username_3**: @username_4 Yes they would, and also if there is light reaching the ocean floor, life can flourish right there where the nutrients are, like in coral reefs. However, it is unlikely that and ocean world would be shallow. In such case there would most likely be dry land too.  

---

