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Alternative Biochemistries WIP by thomastapir Alternative Biochemistries WIP by thomastapir
A rough draft of a chart attempting to tabulate potential alternative biochemistries across three different dimensions: solvent systems, structural matrices, and genetic coding methods. YELLOW HIGHLIGHTING indicates terrestrial conditions. Will scrap soon, but I wanted the initial exposure for maximum feedback. This is also available as a Word doc if anybody wants a copy to edit, correct, or append themselves.

I rarely do "true" aliens not because I'm uninterested in them, but because I find the potential for creativity so vast and overwhelming that I blanch before the challenge--and, I feel, the responsibility--of creating beings that live up to the implied originality and creative promise of the term "alien." And yet the whole premise fascinates me, the challenge fascinates me; I want to somehow shrink the problem down to a manageable size, reduce it to something I can get a handle on, wrap my hands and brains around. I want a chart defining all the potential factors involved in living systems and life-supporting environments, neatly graphed and correlated and tabulated by statistical probability. I want a table ascribing the likely incidence of different alien biochemistries to various locations based on stellar type and age, planetary proximity to sun, and distribution of resources within the galaxy. I want to be able to posit with reasonable confidence that 65% of life in the Milky Way will be organic, and that 85% of such life will be found in the "zone of metallicity" occupying the central volume of the galactic disc; that of the remaining inorganic life, 15% will be based on silicon rather than carbon, with a mere 10% exploiting a fluorosilicone solvent system and the rest taking advantage of high-temperature sulfuric acid...

I know, this goal would probably take a lifetime to realize and may very well be impossible, but it's one I can't get out of my head. These paltry charts are a very tentative first attempt at this undertaking, a tiny drop in a vast bucket, and yet even they are so far incomplete and probably inaccurate and desperately lacking in more alternatives. That's where I need the help of my brilliant and creative dA friends. What are some other alternatives to carbon? To oxygen? To DNA? What kind of life-supporting substances would go into solution (yet remain stable) in methanol, or in hydrogen chloride? (Most of the blanks on that first chart represent solvents suggested in passing by Peter Ward in his book Life As We Do Not Know It.) My text references are limited, I've pretty much exhausted Wikipedia as a resource, Google searches have been frustratingly unproductive, and even academic databases are lacking. This is the kind of endeavor that requires not just raw data but informed opinions drawing on a knowledge base I lack--and that's where I'm hoping my imaginative and better-educated friends will come to the rescue.

And there are SO MANY factors I want to address, beyond mere physics and chemistry: potential alternatives not just to the known terrestrial kingdoms of life, but to the entire domain of cellular life, like Seilacher's original interpretation of the Ediacaran "vendobionts." Even given the assumption of pervasive cellularity, I want to explore the relative likelihood of independent (extraterrestrial) convergence on terrestrial body plans. Will selection factors inevitably lead to cephalization and bilateral symmetry in motile organisms, or is the apparent fitness of this design an illusion created by its prevalence on Earth through our shared origin in a default basal template established by Hox genes ([link])? What does this say for the possible emergence of truly divergent body plans on other worlds? Will we encounter ecosystems of Wheels ([link]) and Moebius Fish ([link])?, or will morphology as we know it prevail throughout the universe...? Educate me, brainstorm with me, help me fill in the gaps and expand this endeavor beyond my wildest dreams!

75% of Sun-type stars are older than our own and therefore likely to host planets with older (possibly more "highly evolved"?) life--that's one statistic I know for sure. I want to know MOAR.

7.15.09 UPDATE:

Revised to reflect ~labgnome's ([link]) incredibly helpful input. The genetics portion especially has been significantly revised and expanded, but there are additions to each section. There are still gaps and I'm sure inaccuracies, wholly my own, which are why this is still a Work In Progress.

I also hope to do a flowchart of potential morphologies reflecting my exchanges with Dan Bensen ([link]) and ~spinery ([link]) on alternative "topologies" and "geometries" as they might apply to alien body forms.
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:iconmechatherium:
Mechatherium Featured By Owner Edited Jan 28, 2017  Student Digital Artist
Water is so common in the Cosmos that "ammonia" may be more likely to be an ammonia/water solution. Ammonia/water solutions can remain liquid down to 173K (-100 deg. C, -148.270 deg. F).

I find Wikipedia a useful place to start research: en.wikipedia.org/wiki/Ammonia

EDIT: Hydrogen cyanide might be too reactive to be a solvent. Hydrogen sulfide might react with metabolically active minerals like iron to form insoluble sulfides, IDK.

Just my $0.02
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:iconluka1184:
luka1184 Featured By Owner Dec 11, 2016
Very useful, thank you!!
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:iconthomastapir:
thomastapir Featured By Owner Dec 11, 2016
My pleasure, I hope it comes in handy!
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:iconpeteridish:
PeteriDish Featured By Owner May 22, 2012  Hobbyist General Artist
WOW! =O
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:iconarborine:
Arborine Featured By Owner May 17, 2012   General Artist
This is dead handy, and definite food for thought - thank you!
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:iconthomastapir:
thomastapir Featured By Owner May 17, 2012
My pleasure, I hope you get some use out of it!
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:iconmoriadne:
Moriadne Featured By Owner Apr 2, 2012  Hobbyist Digital Artist
This is fantastic!

Good luck on those flowcharts! Would love to see them as well!
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:iconthomastapir:
thomastapir Featured By Owner Apr 3, 2012
Thanks very much! Man, I need to get started on those one of these days. SO DAUNTING. D :

Appreciate the feedback, I'm glad you like this!
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:iconenigmaticworld:
enigmaticworld Featured By Owner May 22, 2011
VERY interesting... you say there is a doc version? :>
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:iconthomastapir:
thomastapir Featured By Owner May 23, 2011
There is! Just note me an e-mail addy if you'd like a copy. :)
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:iconbill-porta:
Bill-Porta Featured By Owner Jan 27, 2011
I'm working on a project about an alternative biochemistry based on phosphorus and nitrogen... That will be useful and helpful :) ... Thanks
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:iconthomastapir:
thomastapir Featured By Owner Jan 27, 2011
Sounds like an awesome project! I hope this chart does come in handy for you...Thanks for the watch and the fave! :)
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:iconbill-porta:
Bill-Porta Featured By Owner Jan 27, 2011
Anytime...:D
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:iconsaturnineoranges:
SaturnineOranges Featured By Owner Apr 28, 2010
[link]

The above link goes to the National Academy of Science of the United States of America website, to an abstract entitled, "Some implications of an alternative structure for DNA" by V Sasiekharan, N Pattabiraman, and G Gupta.

Then This Link: [link]

is to the full PDF of the article.
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:iconthomastapir:
thomastapir Featured By Owner Apr 29, 2010
VERY interesting...Thank you!

It seems like the, um, non-double-helix model would almost certainly be less compact and therefore less efficient from a biological standpoint, but the ease of strand separation would make it favorable for lab experimentation, which is I assume what they were going for. I also found it interesting that it's more energetically efficient; perhaps it's something that would be selected for under certain circumstances in nature, such as when total organism size isn't as much of a constraining factor (Jovian floaters?).

Thanks again, that's fascinating stuff!
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:iconsaturnineoranges:
SaturnineOranges Featured By Owner Apr 25, 2010
This is extremely interesting...

One other thing to ponder would be what brain/ganglia-analogus structures/systems alien life might have. If you consider it, the brain/ganglia-neuron model is rather complex (..although also rather ubiquitous), so the chances of it occuring again, far away, in a different environment...are low I think. So what other models could there be? If I think of anything good, and with science to back it up, I'll write something up...but right now I'm just going to file it.

Anyway, great job! :w00t:
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:iconthomastapir:
thomastapir Featured By Owner Apr 26, 2010
Wow, that's a damn good point on potential alternate brain structures...I wouldn't even know how to chart it! On likelihood of incidence, I tend to think that the integration and coordination of sensory input (assuming "senses" and "input") will be of such an overwhelming evolutionary advantage that it will tend to be selected for rather than not, at least in motile organisms playing a part in any kind of producer/consumer ecology resembling our own. What form that neural "complexification" might take is a whole 'nother can of worms...I've heard suggestions ranging from solid-state "bioelectronics" to tubulin molecules acting as quantum waveguides. In the organic realm, I think it would be intriguing to look at what aspects of neural complexity may have evolved independently in multiple lineages on Earth--if any. Might be a good indicator of evolutionary fitness, providing a model to apply to non-terrestrial organisms.

Thanks for the great feedback and the fave! :thumbsup:
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:iconwhalewithlegs:
whalewithlegs Featured By Owner Jul 29, 2009
Wah, once again I'm trying to look at this seriously and can feel the valves in my brain shutting down in rapid succession. I tend to approach things from the, "If it exists, we can explain it" platform, which is basically what I think good half of 'real' science is anyway :p

Biology does open some of the canal locks though ... DNA varieties & alternatives! I hadn't looked into that sort of thing before!
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:iconthomastapir:
thomastapir Featured By Owner Jul 30, 2009
Hey, no pressure or obligation to master the nuances of molecular biochemistry in the week before you move to Taiwan! Or ever, for that matter. Like I say, I just put this out there for people to take whatever they can get from it, and also from the selfish perspective that I was fishing for knowledgeable friends to fill in some blanks and correct some mistakes. Which several people did. :)

Oh man, I totally hear you on the "if it exists, we can explain it" model of scientific exploration. I think it's the basis of all good science--letting the natural world explain itself to us, and finding means to understand what it's saying. Unfortunately the public perception of science has been distorted into this Frakenstein monster where people tend to believe that Scientists sit around all day dreaming up obscene, half-baked theories to further corrupt the moral fiber of our youth. The state of scientific ignorance in our country especially is absolutely appalling...But I guess that's a rant for another day. :)
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:iconwhalewithlegs:
whalewithlegs Featured By Owner Aug 14, 2009
Haha, oh man, spending a week in Rural Nebraska was pretty eye-opening ... no, scratch that, it wasn't even a week. I took the baby and went home with Ruth's sister who couldn't stand it either. :p

Living on the West Coast allows one a very privileged perspective, i think.
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:iconthomastapir:
thomastapir Featured By Owner Aug 14, 2009
We are typical West Coast elitists! Time for some more Starbucks coffee and smooove jazz.
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:iconwhalewithlegs:
whalewithlegs Featured By Owner Jul 27, 2009
arggh, the proverbial ... doodoo just hit the fan here ... I'll have to look at this in detail later. I've been 'saving' your pieces to look at last (to end the wading through the inbox on a high note) but Don;t think I'm realistically going to get to this for another week here. Mostly my brain just goes, "Oh no, math!" and hides.
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:iconthomastapir:
thomastapir Featured By Owner Jul 27, 2009
Hah, my brain does the same thing! Honestly, it's not that much math. And the chemistry stuff I tried to make as accessible as possible--the idea was just to split it up into a few basic tables where the viewer can, at a glance, get a sense of some different possible alternatives to water, carbon, and DNA.
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:iconwhalewithlegs:
whalewithlegs Featured By Owner Jul 27, 2009
I do love the taste of DNA alternative ... I didn't even notice that aspect to it! This has been just a horrible day for lucidity, though.
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:iconthomastapir:
thomastapir Featured By Owner Jul 27, 2009
Gad, I'm such a heel I forgot to even ask what went wrong earlier...So...What went wrong earlier??
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:iconwhalewithlegs:
whalewithlegs Featured By Owner Jul 28, 2009
Ha, I forgot to even mention, myself ... scattered brain! We found out that our flight was leaving a day earlier than we had been thinking!! Had to cancel a bunch of plans and rush a bunch of ohers. Ended up getting the kids' shots yesterday, but we had to wait for almost 2 hours while we tried to get our provider to fax in our meical records (we couldn't find ours). 3 shots for the 4-year oold, 6 for the baby. ETC!!!
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:iconthomastapir:
thomastapir Featured By Owner Jul 28, 2009
Oh wow, I bet the kids loved that! :ohnoes:

That's a bummer, man...I hope everything worked out okay. Well, even if it did, that's additional stress you don't need on top of an already stressful transition.

Cancelled plans suck, though. :( Hope you still get a chance to say goodbye to old friends and such.

Still, I have to be selfish--it's gonna rock hearing your firsthand reports from Taiwan!
:boogie:
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:iconwhalewithlegs:
whalewithlegs Featured By Owner Jul 28, 2009
Yep! Ruth and I are going to create a blog and try to alternate posts, so hopefully it will be interesting! Still trying to think up names, much less agree on one, ha!

Thanks for your well-wishing! In a lot of ways I am STOKED to get out of Sacramento, but I know I'll miss it. Researching culture shock has been an interesting endeavor ... i read an account of somebody who said that you should always give yourself time to say goodbye to a place, even if you're ready to go right away.
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:iconthomastapir:
thomastapir Featured By Owner Jul 28, 2009
Huh, that's an interesting point...Reminds me of the old "eustress/distress" dichotomy--even "good stress" is still stress!

Well, Ben and Ruth are both biblical names, are they not? Not that I'm a believer myself, but just in terms of synchronicity, maybe you should let the Good Book be your guide. Just please don't settle for something like Benifer! =P
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:iconart5ec:
ART5EC Featured By Owner Jul 21, 2009  Hobbyist Digital Artist
I see that it's a WIP. So for the future might I suggest you add analogs to Adenosine triphosphate (ATP)? I find that I'm in need of one for a project of mine but I can't find much information anywhere...
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:iconthomastapir:
thomastapir Featured By Owner Jul 22, 2009
That's a damn good suggestion! I have to be honest with you, I know very little about the underlying processes behind cellular energy transfer, so it would be hard for me to even research this topic adequately. But I'll keep it in mind, especially now that I know you are looking for alternatives. :)
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:iconpiatnitskysaurus:
Piatnitskysaurus Featured By Owner Jul 16, 2009
Alot of this goes flying over my head, unfortunately. The physiology charts and stuff will be excellent, I anticipate.

Have you looked at the Fuhara website? It's about a worldbuilding project that has created some very impressive alien critters, there are some good alternative bodyforms there. I'll get the link for you.
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:iconthomastapir:
thomastapir Featured By Owner Jul 17, 2009
A lot of this goes over my head too, frankly. I get the basic concepts, but if you asked me to explain the chemistry behind it I would be at a total loss.

That Furaha site is awesome, I've seen it before but when I looked at it way back it had hardly any art or anything. I checked it out again last night after you mentioned it and it looks like they've really expanded it. Do you know who does the art for it?? I couldn't find any credits, except for the name of the site's creator. Maybe he does it all.
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:iconpiatnitskysaurus:
Piatnitskysaurus Featured By Owner Jul 18, 2009
It occured to me when you talked about different bodyplans, and that brought to mind their radially symmetric spidery things.
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:icondracontes:
dracontes Featured By Owner Jul 15, 2009  Hobbyist General Artist
I think I'll filch this *saves* Just for inspiration and as platform for further research ;)
I have nothing more to say (bit wearied from a college exam) except strontium isn't any more potentially radioactive than calcium is. Some of it is radiogenic* but so is some of the calcium.

*Not the same thing: this means "isotope originated from radioactive decay". Some radiogenic isotopes are radioactive themselves but others are stable as is the case for 87Sr and 40Ca.
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:iconsphenacodon:
Sphenacodon Featured By Owner Jul 14, 2009
Argh, chemistry! I'm melting!

Funny, I could never do the chemistry bit for any of my aliens. Never was my strong suit. Now I'm going to have to go sulk in the corner. :)
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:iconthomastapir:
thomastapir Featured By Owner Jul 14, 2009
Sulk in your tent, it's more classically dramatic that way! :nod:

Believe me, I know VERY little about chemistry. I'm intrigued by the concepts but clueless about the mechanics. It was my weakest subject in school--followed closely by math! I got a C in college algebra and haven't taken a single math class since. : P
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:iconsphenacodon:
Sphenacodon Featured By Owner Jul 14, 2009
Chemistry, math, certain aspects of physics... arrrrgh! Now I'm worrying about whether or not they're required in graduate school. :fear:
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:iconbensen-daniel:
bensen-daniel Featured By Owner Jul 13, 2009
Lots of fun!
I'll leave the biochemistry to other people, since I don't know much about the subject, and more importantly, since the overall shape of the organism might not have much to do with its chemical makeup (prove me wrong?)

But what about the general form? Stephen J. Gould said that mobile life-forms are probably always going to look like worms, since it is advantageous to put your mouth and sensory organs in front of you, facing possible food, and put your anus in the back so you leave your waste behind as you move. It looks like bilateral symmetry evolved very far down the metazoan family tree (nearly as soon as cells started to form colonies defined shapes), although it has been secondarily converted back into radiality a couple of times. That suggests to me that we can expect something worm-shaped to evolve on other planets.

Your approach of looking at topology is probably the most fruitful. What other topologies are out there aside from the tube-within-a-tube? Well, I've read books with toroidal life-forms ([link]), life based on (presumably---it's never well-explained) concentric shells of fluids of different viscosity rolling over each other ([link]), and (again, maybe I'm just making this up myself) a sphere that buds off smaller spheres on both inside and outside surfaces ([link]). Maybe another table would be useful :)
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:iconthomastapir:
thomastapir Featured By Owner Jul 13, 2009
:wow: Your comments on "topology" were exactly the kind of conceptual curveball I needed to get me looking at this from a different perspective...And you're absolutely right, body form should be determiend by selection factors acting on relative environmental fitness, rather than on underlying chemistry. Viruses look roughly similar to sea spiders, after all, due entirely to functional demands rather than to any shared evolutionary heritage (to the best of my knowledge). Truly, form follows from function.

So yeah, got me going in all kinds of directions...I'd like to suggest that we further subdivide the issue into "geometry" as well as "topology." Meaning that topology would relate to how an entity orients or defines itself relative to its environment, whether it is a discrete geometric "unit" or whether it is somehow a reversible or partially exposed system with indistinct boundaries, like the Moeibus strip I keep referring back to (only because it's the best example I can think of offhand, please feel free to chime in with others). The geometry aspect would then be the next category "down" from topology, referring to the fundamental form of the organism--i.e., an "orientable" ("non-Moebius") being with defined topological boundary surfaces could fall into a basic geometric category of cylindrical, spherical, toroidal, etc. And then symmetry would be the next level down from there--most macro-scale metazoan life as we know it being cylindrical, but further delineated by symmetry type; radial, bilateral, biradial, etc.

This just opens up so many more possibilities and directions for "going alien" with body plans in a very systematic and methodical way. Gaaah, thanks a lot, now I have to do a whole 'nother chart! :lol:

Seriously though, thanks for the infusion of fresh perspective here, it was just the creative boost I needed!
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:iconbensen-daniel:
bensen-daniel Featured By Owner Oct 22, 2009
Also, from the perspective of an illustrator, it's of course more interesting to draw a picture of something that LOOKS strange. :) Look who I'm talking to.
It might be interesting to make a sort of alien design-tree. Or flow chart? :)
You're welcome. And sorry for the very late reply.
Now back at you:
I've been thinking about plants. What are some alternative light-catching topologies? We have round bush, we have hairy tuft, we have tall central trunks (around which, light gathering structures could be arranged in a ball, a cone, a cylindar, or flat horizontal plates). Oh and if you add algae and kelp, we have amorphous blob, flat sheet against the ground, and horizontal ribbon (vertical if its under water) What else is there?
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:iconthomastapir:
thomastapir Featured By Owner Nov 19, 2009
...Speaking of late replies! :omg:

re: <I've been thinking about plants. What are some alternative light-catching topologies? We have round bush, we have hairy tuft, we have tall central trunks (around which, light gathering structures could be arranged in a ball, a cone, a cylindar, or flat horizontal plates). Oh and if you add algae and kelp, we have amorphous blob, flat sheet against the ground, and horizontal ribbon (vertical if its under water) What else is there?>

You know, it's a really good question, and one to which I've given a lot of consideration. The main problem I run into in terms of alternate plant forms is that their body designs seem more limited by the necessity of having the greatest possible surface area for light exposure. That, to me, appears to limit the options for crazy alternative morphologies, which I often think of as in some way connected to alternate means of environment negotiation anyway (less of an issue for a static, stationary organism).

I mean, I *can* imagine other unusual body designs for plants, but at that point they seem to get more into the realm of alternate energy sources (i.e. chemosynthesis) or begin to blur the lines between what we think of as plants and other kingdoms of life. I like the idea of a "plant" composed of nothing but rubbery tubes, for example, something like vines or liana, but how would that design aid photosynthesis? It seems more appropriate for a vegetable parasite, and nature has already beat me there with the strangler fig.

I was going to mention that ~labgnome posted an interesting journal topic on this subject recently, but I just checked it out and saw that you're way ahead of me. :)

[link]
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:iconbensen-daniel:
bensen-daniel Featured By Owner Nov 24, 2009
Okay, thinking of alternate light-catching morphologies...

1) A hydrogen-filled sack supports a long vertical leaf, like kelp---a kite-tree.

2) Light is collected by colonial organisms rather than single plants. Rather than a single central trunk with branches, you get a mound, which merges with nearby mounds as its diameter increases. At a certain height, horizontal panels are built out from the main mass (perhaps supported by flying buttresses) to trap sunlight---land corals, architect-shrubs

3) Photosynthetic structures are not in vascular communication with the plant's body. Rather, green threads are extruded, left to photosynthesize, then reclaimed when they are full of sugar---hair-plants, web-plants

4)A large, single leaf that moves.

5) A bunch of colonial amimals with photosynthesizing structures that arrange themselves over the walls of their hive.

...
And that's it.
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:iconthomastapir:
thomastapir Featured By Owner Nov 24, 2009
I especially like 3), the photosynthetic threads! It strikes me as the most "alien." 2) has appeal for its resembleance to coral reefs....1) I can see as a Jovian primary producer. I was thinking that one indicator of feasibility for these various hypothetical morphologies would be to look at plant and related photosynthesizing forms that have evolved indepedently on Earth, the extent to which their forms overlap and converge.

Hmm, it's interesting...You've hit on some intriguing possibilities here--certainly more imaginative than anything I've come up with--but it still seems to me that there's a kind of conceptual "brick wall" one runs into when contemplating alien plant forms. And I wonder if that's a matter of our own bias about what constitutes vegetable life, or if it's due to the practical limitations of a functional organism meeting our terrestrial definition of "plant." Do I find myself limited in coming up with ideas out of some zoocentric prejudice or lack of imagination? Or is it the telepathic suppression of my creativity on the part of the plants?

I've always suspected there's something they don't want me to know. :omg:
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:iconbensen-daniel:
bensen-daniel Featured By Owner Nov 29, 2009
I've been thinking about the threads. Perhaps they are spun by something mobile (like spiders or caterpillars) then ingested later after they have collected enough sugar. Or they are extruded out of pores in the wood in loops. One end comes out with fresh fibers, another goes in for the sugars to be re-absorbed.
This system might be less efficient than leaf-based photosynthesis, since the fibers must be continuously manufactured. On the other hand, they don't require water or repair once extruded.


(I think information helps the creative process---I took a plant physiology course in college, which is where most of these ideas come from.)
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:iconlabgnome:
labgnome Featured By Owner Jul 12, 2009
One suggestion I have for an alternative to carbon is boron, when paired with nitrogen it is capable of forming stable benzine-analogue ring molecules. Boron-hydrogen compounds naturally form somewhat complex three-dimensional structures, that could easily for the basis of protein analogue compounds under the right circumstances. It's compounds have a wide variety of functional uses similar to carbon.

Other alternatives, even more exotic include using plasma "cells", at ultra-high temperatures or gas-filled "bubbles" as opposed to fluid filled "cells" as structural alternatives to familiar cell-like or virus-like structures.

Notes:

Silane and silanol compounds wold also be functional in liquid methane environments.

(AGCT) based DNA is not the only possible configuration, and their are other possible "bases" that could be used.

DNA Quadruple-form is also possible resulting in a genetic code that could possibly support even more amino acids.

Also Terrestrial life has used up to 22 amino acids and more are possible, but reduced redundancy, and increased potential for fatal mutation in the organism.

HNA "Hexose Nucleic Acid" is also possible based on a six-carbon rather then five carbon sugar.

"LNA" isn't really a "DNA alternative" from my understanding of it and its functions.

I hope this post is helpful
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:iconthomastapir:
thomastapir Featured By Owner Jul 12, 2009
:wow: WOW, thank you SO MUCH!
What a goldmine...This is exactly the kind of response I was hoping for!

I'd like to follow up on a couple of things, if you don't mind.

Do you think the rarity of boron might pose a problem? I see that it's quite rare on Earth (.001% in the planet's crust) but that there's also some debate about its abundance on a universal scale ([link]). Do you have any particular opinion on this? Might it be much more abundant in certain types of non-terrestrial environments?

What are those other potential alternatives to A-G-C-T as DNA nucleotide bases? Would they fall under the category of the "novel bases" mentioned in this article ([link])?

That "quadruple-form DNA"--would that mean a "quadruplicate nucleotide" sequence? Do you know how many amino acids it would theoretically code for?

I'm fascinated by that "HNA" concept but can find very little about it aside from tantalizing abstracts and fragments of articles related to the "fitness of pentose over hexose nucleic acids." They all look very technical and beyond my comprehension. Do you have any suggestions for something more accessible I could read? (Is there a short answer to the question, "Why would pentose nucleic acids be selected for over hexose"??)

Do you know how many naturally-occurring amino acids have been identified? Is there some place I can find a list of them?

Hope you don't mind me picking your brain...Even if you could point me in the right direction to do my own research, if you don't have the time or inclination to educate me, that would be great.

Any help at all would be much appreciated!

Thanks again for a fantastic response! :wave:
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:iconlabgnome:
labgnome Featured By Owner Jul 14, 2009
The low abundance of boron is an issue, but silicon also has a low, but not as low, abundance doesn't seem to be quite as chemically versatile as boron or carbon. Honestly I think it's a trade off, I've also read that ammonia, rather than water may make an ideal solvent for "boron-organics" rather than water, due to boron's affinity for nitrogen over oxygen. I do remember an article stating that born may actually be significantly more abundant in so-called "dark galaxies" from spectroscopic analysis, so it may simply be that such life is rare or unknown in "normal" galaxies like our own, but more common in "dark galaxies".

The article you linked to is right on the spot, you may want to include the "modified bases" in your speculations.

I'm not sure how many amino acids that would allow, but an initial guess would be, using four bases, four to the fourth power minus one disregarding redundancy, and having only one stop codon, resulting in 255 potential amino acids one 145 more than are known to exist in nature. In theory our codon system could support four to the third power minus one, or 63 amino acids. Our genetic code uses three stop codons and has redundancy reducing the potential amino acids used dramatically. Redundancy is helpful to prevent damaging mutations, by allowing more than one possible codon to produce the necessary amino acid. So in theory a quadruplet-codon DNA (or analogue) could actually harness all naturally occurring amino acids. A quintuplet-codon genetic code could definitely use all 110 naturally occurring amino acids.

I have also seen very little myself, but it has been mentioned. I see it as a possible further step in biochemical evolution bast five-carbon sugars. However if fiver carbon sugars have adavntages they may be less common, but certainly not compleatly excluded from possibility. Even though there is very little I woudl still include it in case more research turns up later.

I don't know of any place that lists and I'm using 110 naturally ocuring amino acids from memory so that may not be relaible. I tried to look it up online but couln't find anythign definitive, so I'll go with what I remeber until somone gives a better supported answer.

I'm more than glad to be of help. I'm actually going to be posting some more from my own attempt at worldbuilding, so feel free to take apart whatever I try to put up. It will contain exobiology speculations, including an outline for abiogenisis, from PNA to HNA.
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:iconthomastapir:
thomastapir Featured By Owner Jul 14, 2009
This is absolutely fascinating, but approaching the limits of my comprehension, so let me just double-check a couple of things here to make sure I'm interpreting them correctly...So assuming quadruplicate-codon DNA can code for 255 amino acids, with 110 the maximum number available, would it be able to code for all 110 amino acids but still allow the same degree of redundancy (and stop codons) as our own (triplicate) coding system? Or would redundancy be compromised? (I'm fuzzy on how the math breaks down here.)

Also, the quintuplicate-codon DNA could obviously take advantage of all 110 amino acids with room to spare for redundancy and stop codons (correct?). But would there be any potential benefit in using all 110 amino acids, or even in using significantly more than the 22 used on Earth? Is there any way to predict with any confidence whether this might be advantageous, and what the advantage(s) might be...?

Thanks again, I REALLY appreciate your input. I'm watching you now and will definitely be following your future postings...I'm sure I'll find them illuminating, even if I don't have much to contribute to the science! :)
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:iconlabgnome:
labgnome Featured By Owner Jul 14, 2009
There would be reduced redundancy, terrestrial life has about triple redundancy in most cases, while quadruple, using all 110 amino acids, would have only double redundancy.

I can't think of a direct natural advantage for using all 110 amino acids, but in an environment dealing with multiple sets of amino acids, something that could use all of them would have an advantage. So I could see an intelligent species that has to deal with many others from different biochemistries either taking advantage of some such life-form that happened to evolve naturally or engineering one for themselves.
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