Caulerpa taxifolia, an algae species popular with aquarium owners, is the largest single-celled organism known to us as of today. It is notable for being able to regenerate from any part of the body and shows structures mirroring normal plant organs, with RNA differing throughout different parts of the organism. It is an invasive species.

In my story, the (zero-G and centrifugal) STL habitats and colony ships of a giant settlement fleet as well surface stations on inhospitable planets extensively farm C. taxifolia for the purpose of human nutrition and feeding cattle.

My question is:

  • Why should C. taxifolia be utilized as the primary nourishing plant in a hard sci-fi, outer-space environment? Which advantages does its macromonocellular structure encompass?
  • $\begingroup$ "Which advantages does its macromonocellular structure encompass?" Advantages with respect to what? There is no such thing as the best crop for ll uses. If all they have is C. taxifolia then they will grow C. taxifolia. If they have multiple choices they will grow multiple crops, each suitable for its intended purpose. $\endgroup$ – AlexP Jan 26 '19 at 20:11

Ease of genetic engineering.

Production of genetically and developmentally modified seaweeds: exploiting the potential of artificial selection techniques

Macroalgal stocks with altered morphological traits can either be continuously collected from the wild or generated on demand in culture facilities using a combination of techniques likely to modify the developmental traits in a stable way.

As opposed to vascular plants, which must be engineered to breed true and then cultivated/sustained from seed through their life cycles, an alga like Caulerpa can have a somatic cell engineered and then be maintained indefinitely from that single cell - much as is the case for engineered bacteria. In theory it is much, much easier. That can be the rationale - various Caulerpa stock have been made with different flavors, vitamin and protein characteristics etc. Your near future astronauts are master engineers of the Caulerpa and just tweak it to be whatever they need.

  • $\begingroup$ From the linked reference: "Cellular biotechnology in seaweeds… lags far behind that of terrestrial plants". AFAIK there have been no green seaweed successfully genetically transformed. Although you make a good point about the somatic cell, I'm not sure how easy it is to maintain Caulerpa cells. In comparison, plant seeds are often fairly robust. $\endgroup$ – Sparhawk Jan 27 '19 at 2:45
  • $\begingroup$ @Sparhawk - my guess about that is that the plants are established and productive crops, and so a GMO plant would have a ready market. As regards C.taxifola it is one of the worst weeds ever and practically unkillable - check the wikipedia article. $\endgroup$ – Willk Jan 27 '19 at 3:09
  • $\begingroup$ Yes, I agree that funding is almost certainly the major factor here. Regarding robustness, I'm not 100% how either organism would survive long-term transport, e.g. perhaps dried seeds might work better. $\endgroup$ – Sparhawk Jan 27 '19 at 3:51

Not knowing anything about this species except what you've given us, I would go with...

It's easier to genetically engineer than anything else

Genetics is complicated. Although we can now sequence DNA, the chain of interactions between all the moving parts of a complete organism are too complicated to work out on a chalkboard or even in a powerful simulation. Re-engineering a species like a human, or even like a honeybee, is something that an entire society can work on for decades and still only make breakthroughs by trial and error.

But with this one species, the system is much simpler. Not simple, but much simpler, with a more direct link between the gene and its expression. We could say that (in your near-future sci-fi story) it has proven within the grasp of genetic engineers to do quite a lot of interesting things with this species. Since they're a "settlement fleet" spreading out to all kinds of different locations, including "inhospitable planets", the practical application is that they can re-engineer variants of the plant to grow in very different environments, and even create varieties that might help to terraform those environments.



It is notable for being able to regenerate from any part of the body

This leaps out at me as a reason to grow it. You can harvest just the amount that you want, when you want. The only restriction is that you need to retain some portion of the plant (ignoring whether this is technically a plant). So you may have to harvest from multiple plants.

This flexibility seems key if you are stuck with relatively few plants. Contrast with a tomato. With tomato plants, you only eat the fruits. You need to harvest the entire fruit, even if you only want half of it at the moment. You have to harvest on a particular schedule. Too early and it's not ripe yet. Too late and it's rotten. You'd have to plan for usage months in advance. And if you grow too little, there's no fix. If you grow too much, you could turn it into sauce and freeze it. But you can't really substitute sauce for sliced tomato the next time you're short.

Assuming this is far enough forward that you can have the plant genetically engineered for nutrition and flavor, this flexibility may make it the plant of choice for long term harvesting. And next door you can have the cultured chicken heart. Or some more modern cultured meat.

I'm thinking that the plant may come in multiple flavors so that chefs (possibly robotic) could mix the flavors so as to make a delightful repast. Or at least that's what the advertising would say.

  • $\begingroup$ So basically like a Minecraft cactus or sugar cane farm? $\endgroup$ – MedwedianPresident Jan 27 '19 at 9:07

It's hardy and can clean sewage

Caulerpa taxifolia is a very hardy organism that thrives in cold water, which makes it both popular for aquariums and a problematic invasive species. It is also resistant to many toxins as well as ultraviolet radiation that would kill other algae and plants, and can live in sewage (and actually absorbs it, helping to clean the water). These make it useful for prospective space travelers, since it can live in many environments and can help with water purification.

...but it's poisonous!

C. taxifolia produces caulerpicin, which is poisonous to eat (although it does not poison the water around it) - this is the other reason why it's an invasive species, it's inedible. Only a handful of animals can eat it and these animals accumulate its toxins in their body to the point where they become toxic themselves. So you're going to have to make a genetically engineered non-toxic strain if you want to use it as a food source. Nevertheless, it may be worthwhile, since it only really has one toxin and it's a lot easier to genetically engineer an organism to not produce a single toxin than to breed a non-toxic species to live in completely different environments.


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