Crabs, convergence and viability.

louis · 2019-03-16 12:56:04

Interesting video from Art Alien TV...

https://www.youtube.com/watch?v=Jzlna_7n7xg

I think he is definitely on to something at 14:00 - that specimen is v. interesting.

The more I think about evolutionary convergence, the more I feel we shouldn't be surprised to find similar looking creatures as on Earth - though whether alive or as fossils is another matter of course.

But is life viable on Mars?

I was thinking about the Antarctic. The conditions there could be said to be better than on Mars and yet life struggles to get any foothold there. Leaving aside birds (penguins) it's not a v. hospitable environment for life is it? And the penguins are of course cheating - getting their nutrition from the sea not the land!

And that made me think - the problem with the Antarctic is that there is so much frozen water and little else that it makes maintenance of life extremely difficult. The six months of near darkness don't help either. Yes, we need water but we also need solar radiation, and then we need to be able to access the range of chemicals that allow us to construct and repair cells. Think about the problem that way, Mars starts to look a better prospect. In the equatorial regions (with less dramatic seasonal change) solar radiation levels are pretty much guaranteed apart from limited periods of reduced radiation due to dust storms (which Mars-based creatures could likely overcome with hibernation techniques of the sort we see on Earth.

Mars life forms have nevertheless to overcome a few challenges that are really centred on the v. thin atmosphere and absence of a magnetosphere.

I don't think pressurisation per se is an issue. Even thin-skinned humans don't immediately explode on being exposed to a near vaccuum. Obviously any life forms would have had millions of year to adapt to a low pressure atmosphere.

The high radiation lives are clearly an issue. I know some will disagree but it appears that the Mars plains are inhospitable to plant life, although there might be some fungi-style forms that survive. So Earth like food chains based on plant life won't easily form on Mars.

One response to radiation would of course to be to develop a thick, hard shell to protect vulnerable inner parts: I'm describing a "crab" there.

Another obvious response would be for life to go underground or into caves. Again we see a possible creature at a cave entrance.

We might find the food chain is really underground with bacteria extracting nutrients from the regolith directly. Mars life forms might make oxygen from processing of iron oxides or similar.

Void · 2019-03-17 18:23:41

Louis,

I am leery about responding as I have been warned that the English love to hoax. But I am 1/4 (Sort of) American English (A bit of French Huguenot, and Scotch in that), so perhaps I am vaccinated against hoaxing, and con proceed to respond.

A first likely case of survival of Martian life from a presumed earlier existing biosphere might be microbes that consume Hydrogen released from radioactive decay. This would likely be down below the surface where chances of wetness might exist. A possible limiter could be how concentrated a brine such water might be. It is possible that aquifers still exist from water that was not so salty, a long time ago. If so, I presume that Earth microbes that are fed by radioactive decay could be transplanted from Earth to the deeps of Mars and they would have chances of grafting themselves into the planet.

A second possible case would be microbes adapted to hyper arid desert conditions.
So adapted that rainfall will kill them, as per this article about that occurrence in the Atacama desert in Chile:
http://astronomy.com/news/2018/11/rainf … r-microbes
For Mars, if like those, presumed to be adapted to hyper arid conditions existed, I would be inclined to think they would consume CO and O2 from the atmosphere. That would indicate that they would exist just below the surface, shaded from U.V., and possibly getting moisture from the following: The day night cycles may allow frost to collect on thin fragments of stone, if salt also existed on the surface of those stones, then even a brine might collect. The cold of night would squeeze less salty water out of the forming ice. Correction, the cold would squeeze out the more briny liquid, leave a less salty ice. Then depending on temperatures and the saltiness of the ice it could melt with the days heat. Further, I do not imagine this process as likely on the top of the thin flat rock but rather more likely on the bottom of the rock. Upon day, then the ice might melt at a sub freezing temperature for fresh water. That is you might have salty water liquid at say 22 degF (-5.56 degC). This might not be very brutal. The salt levels may be low enough for life to tolerate, and the temperature may be high enough for microbes to have metabolic activity. And presuming that they could work with CO and Oxygen, they may have all they need in that case. So, I see this as plausible.

The question of plants or animals? I think plants may be unlikely. Their ability to get water would seem to be limited to me, and their ability to work directly with and tolerate U.V. Is not a thing demonstrated on Earth.

Recently it was suggested that at some cold places on Mars brines could hold a lot of Oxygen perhaps enough for sponges. This life would need to tolerate perchlorates, but actually perchlorates and CO as food might work.

But what about animals without plants? By animal I indicate life with animation. Actually sponges and a few plants have animation as well, but it is very limited on a macro scale, so by animal, I guess I would indicate a creature that can travel through a fluid or across a surface.

IanM, I see your response. That's OK. Even though I do not think multicellular life will be found on Mars, I will still express a best hope case for it. Just for fun.
I think that the Tardigrade comes close, it could even be possible that a distant relative of it could exist on Mars. Unlikely, but the model comes the closest to plausible that I can think of.

https://www.livescience.com/58309-how-t … rying.html

This version would be a very strange thing. Its food could be CO, or microbes. It might just be able to breath Oxygen from the Martian atmosphere, but would need some chemical much better than our Hemoglobin. Also Hemoglobin loves to attract CO even more than Oxygen. So, maybe the Tardigrade would breath it's food and "Eat" Perchlorates. For moisture, perhaps it could hang out under the thin stones I think might provide a less briny liquid. To be warm, it might actually crawl towards the surface, perhaps even onto the surface if it could be tolerant of U.V. In that case it's body would need to be covered in a U.V. absorbing layer that would not degrade excessively. Towards end of day, it would again crawl under the stone where it would hope to get another drink the next day. It's sensory methods may not involve eyesight, as that could be vulnerable to U.V. damage. Electric forces, maybe smell, eco-location? Something else?

So, curiously any such "Animal" would not be dependent on plants.

A planet like Mars creates disequilibrium in it's atmosphere. This leads to the question of other Mars like planets in the Universe that might have many of these factors, such as solar induced disequilibrium, but conditions more favorable to life. Take away the vicious swings in temperature and aridity, and you might have a biosphere entirely without photosynthesis. This could be down deep in water, or perhaps even on the surface. For instance the Atacama Desert has perchlorates for the critters to "Eat-Breath", even though it is on Earth.

….

A partial solution I had at one time for animals to deal with U.V. from solar flares from "M" type stars, would be that they be covered with fur entirely, and that instead of eyes they would have echo location like bats. This might help with the U.V. For radiation of course we even have organisms with circular and multiple DNA, that can deal with severe radiation conditions.

…..

I actually entertain notions of interstellar panspermia. In my version, I include rogue planets and smaller rogue objects as carriers for life.

A recent article speculates that there will be 100 to 100,000 rogue planets for every star in the universe/galaxy/whatever.

If a frozen object, then some microbes can re-animate upon warming after very long lengths of time. Sufficient in a star nursery, for one baby star system to infect another.

Many planets would have liquid water 10 miles down under the right conditions, so that allows for active life. If the planet was bombarded the infection could be expelled from it to another new planet in a star nursery. In fact with bombardments, such a planet could warm up so that the life would emerge to the surface, and be even more likely to have life spread from it by subsequent ejections of bombardment.

Some rogue planets will collect Hydrogen/Helium atmospheres so thick that they will have liquid water on them regardless, possibly a Nitrogen/Else atmosphere below that. Those could be germ carriers.

And I think that some gas worlds could spread life. I have reasoned that the Bacteria sized objects in the clouds of Venus might levitate by electrical force. Spiders do that on Earth. And on Venus, Oxygen is ejected from the atmosphere by electrical force.
A Venus would not be likely to stay that hot as a rogue planet, but I do reason that on some gas planets, electrical levitation might allow life forms to prosper in the atmospheric column.

Where would these life forms come from? Well, I think panspermia would allow the evolution of complex life forms that could be transferred between planets. The electrical levitation type might be hard to transfer, but what if it made spores if ejected from the planet by an impactor? Then the infection of another gas planet could be plausible.

……

The idea of stars capturing rogue planets brings information that it is considered to be very hard to capture a planet, and especially hard to capture one to a "Habitable Zone" I presume.

However I invoke the gas/dust clouds of star nurseries which have not yet formed stars. They have gravitation, and what is even more important is that they can aerobrake a rogue planet into themselves. So, if one such planet carries the infection of life, then it is possible to "Impregnate" all the baby star systems which emerge later. And since those developing star systems will spit up small and large objects including proper planets they can impregnate future star nurseries with life. Way, way in the future.

……

So, in my universe, I allow that the emergence of life does not likely happen from chemicals on suitable planets, but that could be possible that life emerged long ago in the much earlier universe. It is possible that it is only a common form in our galaxy, or some sub-part of the galaxy. It would depend on when it emerged. If it emerged early on in the universe, then it could be in all the galaxies that we can see.

…..

So, Louis asked about "evolutionary convergence". I would say it very likely, especially if life commonly has the same roots from other objects in the distant past of the universe. Having similar roots, and experiencing similar conditions, then we might expect similar outcomes.

Humanoids? Well. It happened on this planet at least once.

…..

And we have little ability to see through well prepared false realities, if the entities creating the false reality are that much more advanced then us. However, we have little choice except to have a look at the evidence we can sense. We can be aware that we may be being fed B.S. But then maybe it is better to behave as expected in our little terrarium.

Done.

Last edited by Void (2019-03-17 21:08:57)

IanM · 2019-03-17 18:43:19

I do think any life on Mars would be unicellular given the conditions. It could exist underground as chemosynthesizers, but the paucity of water is itself an issue.

Void · 2019-03-17 19:45:55

For what it is worth, I would prefer to finish my posts before responses are given. I understand that if others are posting between each other and I do one of my lengthy posts, then I am not being polite. However this topic was dormant for a period of time, and I contemplated that I could formulate the post I did in #2.

A premature response can be a problem for proper communication.

Done.

Last edited by Void (2019-03-17 19:47:25)

elderflower · 2019-03-25 11:22:22

There is an assumption that extraterrestrial life will be cellular like the familiar variety. This is likely correct, but might not be. It is an assumption!

Void · 2019-03-25 14:04:19

Actually, in a partially borrowed idea, I can see the possibility that aquifers, or wave nourished beach sand, might provide voids where subparts of cells would propagate, possibly by assisting each other. Cells though would then be the result of an assembly of these tiny caged processes graduating eventually to somehow generate their own, cell walls and then to be able to propagate in other than nurseries in the rock and sand.

But I must tell you that I am inclined to believe in a higher power. On for whom the enormous time spans speculated on are merely a afternoon tinkering in the garage. In other words, I am inclined to believe in intentional purpose of creation. But of course such a being(s) are so beyond us, that our concept of such is vague at best.

If you reply with the standard atheist reply, I may or may not choose to engage you. My option.

Done

louis · 2019-03-25 17:07:37

But what if multicellular life developed when conditions on Mars were very much more Earth-like? Once multicellular life is established I think it is quite difficult to eradicate it entirely because it is supremely adaptable (with a lot of hidden genetic "switches" that can be brought into play if the environment changes - epigenetic evolution). Even the "Dead Sea" on Earth has some organisms and fungi. The thesis that life would largely go "underground" if the surface environment changed dramatically seems reasonable to me.

Anyway, if you don't accept the possibility of multicellular life on Mars, then you have a lot of v. weird artefacts that you have to "explain away" as rocks. I should add even three years ago I was a total sceptic about macroscopic life on Mars. It is only through viewing so many remarkable artefacts on Mars, that I feel we have to open our minds to the possibility, although of course confirmation awaits humans on Mars.

IanM wrote:

I do think any life on Mars would be unicellular given the conditions. It could exist underground as chemosynthesizers, but the paucity of water is itself an issue.

louis · 2019-03-25 17:40:35

I think things are very open at the moment. Panspermia seems more likely now than it did a few years ago.

Since first learning about rogue planets, I've always been attracted to the notion of such planets passing through huge distances over hundreds of millions, perhaps billions of years, with self-sustained life support systems (e.g. through gravity induced heat production etc). Again not something to be discounted until we locate and investigate a big rogue planet at some as yet far off date.

On Earth there isn't the evolutionary pressure for macro life forms to do the basic nutrition extraction if that is being performed by much smaller organism down the food chain. But in a disrupted world where perhaps lots of food chains broke down either because of a catastrophic event or big planet-wide changes over millions of years, large organisms might develop the ability to extract nutrients directly.

Void wrote:

Louis,
I am leery about responding as I have been warned that the English love to hoax. But I am 1/4 (Sort of) American English (A bit of French Huguenot, and Scotch in that), so perhaps I am vaccinated against hoaxing, and con proceed to respond.
A first likely case of survival of Martian life from a presumed earlier existing biosphere might be microbes that consume Hydrogen released from radioactive decay. This would likely be down below the surface where chances of wetness might exist. A possible limiter could be how concentrated a brine such water might be. It is possible that aquifers still exist from water that was not so salty, a long time ago. If so, I presume that Earth microbes that are fed by radioactive decay could be transplanted from Earth to the deeps of Mars and they would have chances of grafting themselves into the planet.
A second possible case would be microbes adapted to hyper arid desert conditions.
So adapted that rainfall will kill them, as per this article about that occurrence in the Atacama desert in Chile:
http://astronomy.com/news/2018/11/rainf … r-microbes
For Mars, if like those, presumed to be adapted to hyper arid conditions existed, I would be inclined to think they would consume CO and O2 from the atmosphere. That would indicate that they would exist just below the surface, shaded from U.V., and possibly getting moisture from the following: The day night cycles may allow frost to collect on thin fragments of stone, if salt also existed on the surface of those stones, then even a brine might collect. The cold of night would squeeze less salty water out of the forming ice. Correction, the cold would squeeze out the more briny liquid, leave a less salty ice. Then depending on temperatures and the saltiness of the ice it could melt with the days heat. Further, I do not imagine this process as likely on the top of the thin flat rock but rather more likely on the bottom of the rock. Upon day, then the ice might melt at a sub freezing temperature for fresh water. That is you might have salty water liquid at say 22 degF (-5.56 degC). This might not be very brutal. The salt levels may be low enough for life to tolerate, and the temperature may be high enough for microbes to have metabolic activity. And presuming that they could work with CO and Oxygen, they may have all they need in that case. So, I see this as plausible.
The question of plants or animals? I think plants may be unlikely. Their ability to get water would seem to be limited to me, and their ability to work directly with and tolerate U.V. Is not a thing demonstrated on Earth.
Recently it was suggested that at some cold places on Mars brines could hold a lot of Oxygen perhaps enough for sponges. This life would need to tolerate perchlorates, but actually perchlorates and CO as food might work.
But what about animals without plants? By animal I indicate life with animation. Actually sponges and a few plants have animation as well, but it is very limited on a macro scale, so by animal, I guess I would indicate a creature that can travel through a fluid or across a surface.
IanM, I see your response. That's OK. Even though I do not think multicellular life will be found on Mars, I will still express a best hope case for it. Just for fun.
I think that the Tardigrade comes close, it could even be possible that a distant relative of it could exist on Mars. Unlikely, but the model comes the closest to plausible that I can think of.
https://www.livescience.com/58309-how-t … rying.html
This version would be a very strange thing. Its food could be CO, or microbes. It might just be able to breath Oxygen from the Martian atmosphere, but would need some chemical much better than our Hemoglobin. Also Hemoglobin loves to attract CO even more than Oxygen. So, maybe the Tardigrade would breath it's food and "Eat" Perchlorates. For moisture, perhaps it could hang out under the thin stones I think might provide a less briny liquid. To be warm, it might actually crawl towards the surface, perhaps even onto the surface if it could be tolerant of U.V. In that case it's body would need to be covered in a U.V. absorbing layer that would not degrade excessively. Towards end of day, it would again crawl under the stone where it would hope to get another drink the next day. It's sensory methods may not involve eyesight, as that could be vulnerable to U.V. damage. Electric forces, maybe smell, eco-location? Something else?
So, curiously any such "Animal" would not be dependent on plants.
A planet like Mars creates disequilibrium in it's atmosphere. This leads to the question of other Mars like planets in the Universe that might have many of these factors, such as solar induced disequilibrium, but conditions more favorable to life. Take away the vicious swings in temperature and aridity, and you might have a biosphere entirely without photosynthesis. This could be down deep in water, or perhaps even on the surface. For instance the Atacama Desert has perchlorates for the critters to "Eat-Breath", even though it is on Earth.
….
A partial solution I had at one time for animals to deal with U.V. from solar flares from "M" type stars, would be that they be covered with fur entirely, and that instead of eyes they would have echo location like bats. This might help with the U.V. For radiation of course we even have organisms with circular and multiple DNA, that can deal with severe radiation conditions.
…..
I actually entertain notions of interstellar panspermia. In my version, I include rogue planets and smaller rogue objects as carriers for life.
A recent article speculates that there will be 100 to 100,000 rogue planets for every star in the universe/galaxy/whatever.
If a frozen object, then some microbes can re-animate upon warming after very long lengths of time. Sufficient in a star nursery, for one baby star system to infect another.
Many planets would have liquid water 10 miles down under the right conditions, so that allows for active life. If the planet was bombarded the infection could be expelled from it to another new planet in a star nursery. In fact with bombardments, such a planet could warm up so that the life would emerge to the surface, and be even more likely to have life spread from it by subsequent ejections of bombardment.
Some rogue planets will collect Hydrogen/Helium atmospheres so thick that they will have liquid water on them regardless, possibly a Nitrogen/Else atmosphere below that. Those could be germ carriers.
And I think that some gas worlds could spread life. I have reasoned that the Bacteria sized objects in the clouds of Venus might levitate by electrical force. Spiders do that on Earth. And on Venus, Oxygen is ejected from the atmosphere by electrical force.
A Venus would not be likely to stay that hot as a rogue planet, but I do reason that on some gas planets, electrical levitation might allow life forms to prosper in the atmospheric column.
Where would these life forms come from? Well, I think panspermia would allow the evolution of complex life forms that could be transferred between planets. The electrical levitation type might be hard to transfer, but what if it made spores if ejected from the planet by an impactor? Then the infection of another gas planet could be plausible.
……

The idea of stars capturing rogue planets brings information that it is considered to be very hard to capture a planet, and especially hard to capture one to a "Habitable Zone" I presume.
However I invoke the gas/dust clouds of star nurseries which have not yet formed stars. They have gravitation, and what is even more important is that they can aerobrake a rogue planet into themselves. So, if one such planet carries the infection of life, then it is possible to "Impregnate" all the baby star systems which emerge later. And since those developing star systems will spit up small and large objects including proper planets they can impregnate future star nurseries with life. Way, way in the future.
……
So, in my universe, I allow that the emergence of life does not likely happen from chemicals on suitable planets, but that could be possible that life emerged long ago in the much earlier universe. It is possible that it is only a common form in our galaxy, or some sub-part of the galaxy. It would depend on when it emerged. If it emerged early on in the universe, then it could be in all the galaxies that we can see.
…..
So, Louis asked about "evolutionary convergence". I would say it very likely, especially if life commonly has the same roots from other objects in the distant past of the universe. Having similar roots, and experiencing similar conditions, then we might expect similar outcomes.
Humanoids? Well. It happened on this planet at least once.
…..
And we have little ability to see through well prepared false realities, if the entities creating the false reality are that much more advanced then us. However, we have little choice except to have a look at the evidence we can sense. We can be aware that we may be being fed B.S. But then maybe it is better to behave as expected in our little terrarium.
Done.

Void · 2019-03-26 11:28:43

Louis,

Nice response. I will agree that panspermia is "More likely". I also of course could have my opinion changed by evidence in the future, and would not be very disappointed by being wrong. But I believe that suspecting it's existence is appropriate, so that we will be aware to look for evidence to support the idea. So going to Mars and checking Venus, and also ocean moons will be important to calibrate our notions of reality.

I do mention that radioactivity will also be a source of heat for objects, either circling stars, or migratory Rogue objects that might get captured to a star nursery when it is quite young, and so might infect such a star nursery. The presence of super nova seem to be necessary for Aluminum 26 to be included in small objects which it can heat up for millions of years to make muddy objects in a star nursery. For objects as large as Earth, other more long lived radioactive substances are needed.

One very interesting thing to consider, is the migration of gas giant and ice giant planets towards a star, or the proposed capture of a rogue planet into a star nursery when it is quite young. Jupiter's proposed early history suggests the possibility of life bearing capability in it's infancy.

Quote:

I think things are very open at the moment. Panspermia seems more likely now than it did a few years ago.
Since first learning about rogue planets, I've always been attracted to the notion of such planets passing through huge distances over hundreds of millions, perhaps billions of years, with self-sustained life support systems (e.g. through gravity induced heat production etc). Again not something to be discounted until we locate and investigate a big rogue planet at some as yet far off date.
On Earth there isn't the evolutionary pressure for macro life forms to do the basic nutrition extraction if that is being performed by much smaller organism down the food chain. But in a disrupted world where perhaps lots of food chains broke down either because of a catastrophic event or big planet-wide changes over millions of years, large organisms might develop the ability to extract nutrients directly.

https://phys.org/news/2019-03-jupiter-u … solar.html
The article suggests that Jupiter formed 4 times further out than it is now, and that it was at that time no bigger than the Earth.

This then suggests that as it migrated towards the sun, of course the solar flux increased, but during that migration it accreted much more mass. Of course eventually it became a young version of the Jupiter we see, and would not appear to be so hospitable to life. But in between those points it could have been a ~Earth sized object more composed of solids, but still potentially having an extensive very greenhouse effective atmosphere, high in things like Methane, and yet with other life supporting gasses. In other words, its surface could have been warm even at distances further from the sun than Mars, or even further out than Jupiter is now. And it appears that there could have been other such warm objects, which later collided or were tossed out of the solar system. If one star system in a star nursery were infected with life and was tossing it about, objects such as Jupiter might have been available to receive the infection even if the inner planets were not yet ready. It is a possibility which makes the spread of life's infections a bit more plausible.

We can also add that the activity of accretion which would be going on would also add heat to an embryonic Jupiter. That could be favorable or hostile to life depending on the nature of the accretion. But we also have embryonic other outer planets which might have hosted life before they acquired their present natures. (And their moons, if those were wet inside).

Done.

Last edited by Void (2019-03-26 19:00:14)

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#1 2019-03-16 12:56:04

Crabs, convergence and viability.

#2 2019-03-17 18:23:41

Re: Crabs, convergence and viability.

#3 2019-03-17 18:43:19

Re: Crabs, convergence and viability.

#4 2019-03-17 19:45:55

Re: Crabs, convergence and viability.

#5 2019-03-25 11:22:22

Re: Crabs, convergence and viability.

#6 2019-03-25 14:04:19

Re: Crabs, convergence and viability.

#7 2019-03-25 17:07:37

Re: Crabs, convergence and viability.

#8 2019-03-25 17:40:35

Re: Crabs, convergence and viability.

#9 2019-03-26 11:28:43

Re: Crabs, convergence and viability.

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