Extraterrestrial life; what could it look like?

[ProtoJeb21]

Life would look like whatever it needs to survive and to fill in all the niches of its environment. I expect the general types of organism structures to be dependent on the type of planet they live on. 

Let's take LHS 1140b as an example. It's a true heavyweight Super-Earth of 6.65 M_E, but only around 1.43 R_E. As a result this planet is incredibly dense at a whopping 12.54 g/cm³ - over 2.2 times as dense as Earth - with a gravitational pull of 3.25 gees. That force is great enough to possibly make a full grown man black out. On such a hefty planet like this, legs would be incredibly inefficient. Gravity would crush the body of the creature closer and closer to the ground, and the amount of energy to even move a SINGLE foot would be too much for a creature to collect on a daily basis. But how about slithering? Most life on a high-gee habitable zone planet like LHS 1140b would probably be similar to worms or snakes, with long, slithery bodies for easier locomotion and likely some other appendages for separate purposes. Some could be used for moving soil out of the way, others for sensing chemicals, and probably some for feeling an organism's physical environment. Sea creatures would probably have to be rather flat, on the other hand, if they would be able to collect enough water beneath them to counter the force of gravity and keep them aloft in the ocean. They would also be small and compact in order to survive the extreme pressures, similar to deep sea fish here on Earth.

Other conditions would impact the appearances of extrasolar biology. Let's keep using LHS 1140b for our example planet. Along with high gravity, this massive planet is constantly bathed in low-energy (but friendly) red light and also has a much higher abundance of metals in its crust. Also, such a dense planet in this orbit around a red dwarf would likely have extreme volcanism pumping out noxious gases, smooshed-down continents that would basically be giant island chains, a thick warm atmosphere distributing heat all around the planet, and rather long days caused by an orbit-spin resonance. This would give life on LHS 1140b many advantages and challenges. The abundance of heavier elements would also mean a surplus of the building blocks for life, and the structure of the planet's "continents" would allow for many of Darwin's small warm ponds. Life could have started up quite easily here. Once it got more complex, things like very long days and low sunlight would begin to drive evolution. Plants would evolve to be black in color and mainly a giant bulb, which would collect as much sunlight as possible during the days to drive chemical reactions during the night. Over the course of days of darkness, these bulb-plants would use excess energy to create a goo of nutrients in which they can survive on for many Earth days at a time. Animals may not use regular vision, but instead may "see" their world through chemical reactions. Some predatory species could still evolve eyes - maybe multiple pairs that see in different wavelengths, like infrared and UV. There may also be creatures that don't move at all and just wait for something to move past before latching onto and devouring it. 

So, in conclusion, what exobiology would look like depends on two broad categories: the traits/conditions of the host planet, and the limits of one's imagination. I can go on all day about fictional species of...things...on LHS 1140b but if I would then I may risk boring you guys to death!  

[Spaceception]

@ProtoJeb21 What's the verdict for GJ 3323b? That's pretty Earthlike in terms of size, receives 20% more light than Earth, and has a really short orbital period. 

Or, even K2 3 d? That's even bigger than LHS 1140b.

Edited August 4, 2017 by Spaceception

[ProtoJeb21]

9 hours ago, Spaceception said:

@ProtoJeb21 What's the verdict for GJ 3323b? That's pretty Earthlike in terms of size, receives 20% more light than Earth, and has a really short orbital period. 

Or, even K2 3 d? That's even bigger than LHS 1140b.

GJ 3323b may actually be uninhabitable. Using the stellar luminosity provided by the planet's discoverers, it would have an equilibrium temperature of around 320*K. That would make it a Venus analogue. The super-high ESI was calculated using the PHL's planetary calculator, which predicted a lower luminosity for GJ 3323.

K2-3d is even worse. While LHS 1140b would likely resist a runaway greenhouse effect due to its low stellar flux, the former is too close to its star and too dense to avoid catastrophe. K2-3d is an 11 Earth mass planet stuck inside an object only 50% larger than Earth. This gives it an incredible density of 18.135 g/cm^3, suggesting a composition of over 90% iron (which makes no sense because its star is metal-poor). Its gravitational pull is even higher than LHS 1140b, at a whopping 4.93 gees. That's enough to put people unconscious and probably crush any water into Ice-VII. So no life here, but it may have a Mars-sized moon that could support life. I believe that the only way K2-3d (Galene) could build up a huge iron content is by smashing into and eating up many other planets. These collisions could've formed a moon large enough to maybe be habitable.

[magnemoe]

2 hours ago, ProtoJeb21 said:

GJ 3323b may actually be uninhabitable. Using the stellar luminosity provided by the planet's discoverers, it would have an equilibrium temperature of around 320*K. That would make it a Venus analogue. The super-high ESI was calculated using the PHL's planetary calculator, which predicted a lower luminosity for GJ 3323.

K2-3d is even worse. While LHS 1140b would likely resist a runaway greenhouse effect due to its low stellar flux, the former is too close to its star and too dense to avoid catastrophe. K2-3d is an 11 Earth mass planet stuck inside an object only 50% larger than Earth. This gives it an incredible density of 18.135 g/cm^3, suggesting a composition of over 90% iron (which makes no sense because its star is metal-poor). Its gravitational pull is even higher than LHS 1140b, at a whopping 4.93 gees. That's enough to put people unconscious and probably crush any water into Ice-VII. So no life here, but it may have a Mars-sized moon that could support life. I believe that the only way K2-3d (Galene) could build up a huge iron content is by smashing into and eating up many other planets. These collisions could've formed a moon large enough to maybe be habitable.

K2-3d is weird, how could it be so dense, its so large it should also have lots of rock and probably water and gasses too. 
It could be the naked core, perhaps two cores with the rest thrown off in an planet collision like the one created the Moon. 
I say its an very puzzling object 

[ProtoJeb21]

21 minutes ago, magnemoe said:

K2-3d is weird, how could it be so dense, its so large it should also have lots of rock and probably water and gasses too. 
It could be the naked core, perhaps two cores with the rest thrown off in an planet collision like the one created the Moon. 
I say its an very puzzling object 

A collision hypothesis is quite likely, considering that the two inner planets are rich in water and gas. K2-3b/Phorcys is about 50% water, and K2-3c/Brigid is a gas dwarf. This proves that these two planets, and possibly Galene, migrated closer to their star. Such orbital mayhem would most definitely result in planets smashing together, especially since the space around the host star is much smaller than that of the Sun.

[YNM]

Algae.

Microbes.

Bacteria.

Viruses.

All these four are true wherever you are. They are niches, and they fill all niches.

Complex life, on the other hand, takes much longer process to "make". You'd also need precise historical environtment data to be sure. I mean, we had massive reptiles and massive insects, but nowadays those aren't as rewarding anymore.

Edited August 4, 2017 by YNM

[StupidAndy]

aliens would look like ME!

[Xemina]

As @ProtoJeb21 suggested it would look however it needs to to survive in its niche. But another true thing, as @YNM said, algae, bacteria, microbes and unicellular life are probably more common. Multicellular life, on the other hand, would be lot rarer as it takes Mas* to evolve.
It also depends on the mass, size, gravity and atmosphere of an object, as these are the reasons that life could evolve so well on our planet, Terra (Earth). Furthermore where it is in its system, tidal heating and other aspects play a big part too.
As you know a planet with life needs water (or something like it) in order to survive, the way that scientists think that Earth got it water is from the LHB* about 4 Gas* ago, where asteroids and meteoroids containing water, impacted Earth's surface. Along with the water, scientists think that those asteroids and meteoroids, could have also contained very important ingredients for life, that is why Ceres is so very popular at this moment of time.
If we did find life it would either be on Enceladus or Titan, as  those may have the ingredients of life. If not in the solar system, It could either be unicellular life, using Retin to photosynthesize, or minuscule bugs; It is very, very unlikely we will find life like here on Earth.
Again, as @ProtoJeb21 said, on higher gravity planets, such as LHS 1140b, with a high gravity to suppress, they would evolve a skeletal and muscular structure similar to deep sea fish. Also life would probably not see the same as us, maybe in Ultraviolet or Infared, or maybe they have 16 cones in there eyes; they may not even have eyes, they use there nose, or tongue to find food and guide them.
Temperature, also plays a factor in evolution, pores or tongue, fur or scales?

Let's just be glad Earth is how it is, and we are how we are!

-Ma: Millions of years
-Ga: Billions of years
-LHB: Late Heavy Bombardment
 

Edited August 8, 2017 by Xemina

[YNM]

2 hours ago, DeltaVerb said:

As ProtoJeb suggested it would look however it needs to to survive in its niche. But another true thing, as YNM said, algae, bacteria, microbes and unicellular life are probably more common. Multicellular life, on the other hand, would be lot rarer as it takes Mas* to evolve. ...

I don't say it's rare - multicellular-ism can easily start off an interdependent colony variation, as portuguese man-o-war shows - but predicting their form is very hard. You need historical data. It's not like dinosaurs would immediately die if it was to be alive today on Earth, but the fact that most major organism evolved to become smaller esp. after hoomans means that while the conditions may allow it, life might just push their way wherever it wants. The reverse occurs in specimens such as this.

Intelligent life... well, we haven't been able to fill in Drake Equation to any measure...

Edited August 8, 2017 by YNM

[Xemina]

19 minutes ago, YNM said:

I don't say it's rare - multicellular-ism can easily start off an interdependent colony variation, as portuguese man-o-war shows - but predicting their form is very hard. You need historical data. It's not like dinosaurs would immediately die if it was to be alive today on Earth, but the fact that most major organism evolved to become smaller esp. after hoomans means that while the conditions may allow it, life might just push their way wherever it wants. The reverse occurs in specimens such as this.

Intelligent life... well, we haven't been able to fill in Drake Equation to any measure...

Oh, yes. I'll change it! 

From: Multicellular life, on the other hand, would be a lot rarer as it takes Mas* to evolve.

Now:  Multicellular life, on the other hand, would be rarer as it takes longer to evolve.

Edited August 8, 2017 by Xemina