Living Continents

[JoanDrake]

What would living things the size of terrestrial continents be like? I'm assuming they're on something like a Dyson Sphere or Ringworld

 

[Salvelinus]

I imagine our largest organisms on earth might provide a model.

Our largest organisms are plants or fungi species that have the potential to vegetatively reproce via root (or in the case of fungus, hyphae) networks. For example, the largest organism known now is a large patch (around 100 acres I believe) of aspen trees, all of which are individual ramets of the same organism which has reproduced by sprouting off new trees from its root system. Theoretically, there is NO LIMIT to the size such organisms can reach.

So what do you need to get so large? First of all, you need time! The example above is not only the largest organism, it is the oldest (80,000 yrs). Second, you need stability. By that I mean uniform, favorable conditions in which to grow over a long time. This would be why such organisms grow in soil, as this is a stable environment which is buffered from cataclysmic surface events, such as global temperature swings, wildfires, windstorms etc. Third, you need minimal biotic resistance, so a lack of predators/competitors.

So in answer to your question, something like that whose biomass is largely hidden in some sort of stable matrix.

 

[Nik]

Um, IIRC, there's a 'looks like sea-weed' that is a form of multi-nucleate algae, can grow to immense size.

Then there's the humble slime-mould, which is an 'animal' of sorts...

As Salvelinus says, you need a sufficiently stable environment...

An aquatic 'super-Earth' around a 'brown dwarf' sub-star might do-- No red-dwarf flares, just modest tides and deep time...

 

[chrispenycate]

Actually, the surface of a planet might not be the optimal The largest 'organism' that comes to mind is Fred Hoyle's "Black Cloud", a sentient interstellar dust cloud several times larger than planet Earth. A baby one might be merely continent size.
Of course, sentience on this scale would be very slow, due to light-speed limitations between (nowhere is this problem addressed in the "Powers that be" series' sentient planet) Not stable as in unchanging, but as in 'the problems are always the same'.

Another environment that could possibly support organisms of this size might be floating in the atmosphere of a gas giant planet.

Of course, neither of these environments would give organisms quite as we recognise them…

 

[The Ace]

I notice nobody's mentioned Great A'Tuin yet.

 

[Ursa major]

What worries me is that something this size could be incontinent.



Sorry.

 

[the smiling weirwood]

Have any of you read Orson Scott Card's Homecoming series? This thread reminded me of those books. Card describes the Earth itself as a giant sentient chemo-organic computer of some sort. The premise was that the interior of the continental plates acted as a sort of constantly deposited and renewed silicate matrix along which the electrical currents of the planet's interior made merry and gave rise to a literal Mother Earth. Not hard science fiction, mind you, but interesting all the same.