not if the animal is cracking the seeds open(like squirrels) or cooking them(like the squirrels at the house i had in Florida)
all of those are mixotrophs even though one is most definitely an autotroph in its early stages of life. a plantoid would definitely have to eat but it would be specifically to acquire minerals and water. they would most likely use sunlight for the majority of their energy.
Don’t plants also eat? Plants can’t survive off of autotrophy alone, they get nutrients from the soil or from eating small animals. So doesn’t that make them mixotrophs as well?
they dont ever eat small organsims
they eat the waste of bacteria who consume the dead small organisms
so no
theyre still autotrophs
That’s just not true? There’s a whole niche of carnivorous plants. And eating waste is still not making your own food.
yes
i made a blunder there
but just so you know
those resources are the ones plants use to make their own food
heterotrophs gain energy directly from eating other organisms and stealing it from them
autotrophs make their energy through resources in the environment
carnivorous plants don’t eat to gain energy, they eat just to get minerals (they are incapalbe of producing energy from eating), which is the reason they thrive in soild with low minerals.
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I have an idea. Albeit it would break the whole organism mode of the first three and a half stages. I suggest giving sessile autotrophes or just sessile a more of strategic type of gameplay. Instead of an only one org.
I’m not sure how to make it, but it would be intresting, original and maybe fun. If that isn’t an option, then give a speed up feature simmilar to hoi4 and other paradox grandstrategies, because growing up as an plant is an endless process and it would take a long time
That’s what they were planning already lol
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Good didn’t know that. Didn’t find anything like that in the dev wiki
What would an autotroph’s culture actually be like? A big part of human culture is related to getting food, which simply isn’t a problem for autotrophs. Sure, they need nitrogen and such, but that’s easily found in pretty much any soil
Their main concern will probably be to do with getting light, which is a rather unique concern: On the one hand, light is easily availible, but on the other it is nigh-impossible to transport without electronics and modern technology. Even basic ideas like housing would be completely different for these autotrophs
We need the discuss the fact that auto evo would give every creature photosynthetic skin. Sure, that may not supply all the energy needs of the creature, but why (not have it) when you can (have it)?
Why won’t animals in real life do photosynthesis? The previous posts here said that the chloroplast is heavy. Like, heavy heavy? A leaf is pretty light, I can have myself covered with that. A reason may be camouflage, as being green may not be ideal in all environments, but also, not every animal uses camouflage.
Assuming we can play as an autotroph creature, I don’t think intelligence would evolve. You don’t have to move, or do anything really, why would you need those neurons? If it is a mobile animal that does photosynthesis a little, nothing much changes in that case, except in summer all trade and activities may stop as people sunbathe. Or there could be a cast system where the higher classes “farm” lower classes.
Intelligence can be very useful in areas other than finding food. Active camoflague, air navigation, and social connections are all useful skills that require intelligence and provide benefits beyond finding food
What trade and activities would they be stopping for the sake of sunbathing? Whatever they might need is likely going to be availible in the sun
There are also other things that may be different with autotrophs. Consider their motivations: Unlike humans and other animals, which must go out of their way to look for food, autotrophs don’t really have to do much aside from reacting to the environment. This is going to impact the way they see and interact with the world
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If you get found once, and can’t move, camouflage doesn’t work.
Sessile trees do communicate with their neighbors without having a complex language. They don’t have to run away from predetors or form tribes for cooperation.
The reactions of plants to their environment aren’t as colorful as animals. They don’t have an evolutionary arms race with herbivores which can’t be solved with “make more leaves faster, maybe higher”. Only plant/animal hybrids can be like animals.
maybe
I was thinking of a situation where they have enough sunlight to be sesssile in summer but have to move in winter to get energy another way.
I was considering an autotroph that could move, like a zoophyte or such
Sure, but a more complex communication could be helpful with a more animal-like species
Because auto-evo does mutations semi-randomly and only puts the ones that work the best, as long as there is sonething better it wont happen.
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the actual reason is actually just because earth animals became multicellular before gaining chloroplasts but there is also an animal that does have photosynthetic skin and it already sunbathed for warmth before gaining it. it is called the yellow spotted salamander
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But a photosynthetic skin is the better option. It’s just a normal skin, with the added benefit of photosynthesizing.
Let’s ask this question. Why do we humans make vitamin d from sunlight, but not glucose? I will go over 10 possible reasons.
Also I wrote the conclusions of my ramblings next to the titles.
List of animals and plants mentioned
The treeification* problem
(1) Photosynthesis makes your macroscopic creature too heavy (wrong)
Let’s start with a 5 year old misconception, which was referenced again and again.
The mass of the blade of a leaf, according to the maximum thickness and densities here* is 0,00042 grams for every cm2. According to hhyrylainen’s calculation,^ humans have a surface area of 19000 cm2 and need 49000 cm2 of leaves to survive just from the sunlight. The leaves for those would weigh 7,98 grams and 20,58 grams respectively. Weight turns out to be negligible.
(2) Photosynthesis makes your microscopic creature too heavy (true, but its not clear if weight discourages this lifestyle, also macroscopic creatures can gain traits their microscopic ancestors didn't have)
The source for “photosynthetic stuff is heavy” was this
A chloroplast weighs 80 to 180 million daltons compared to the 10 million daltons of mitochondria. So it is true, at least for cells. But have we ever considered weight as a variable for microbes? They are in a very viscous environment, so an extra weight may even help them move. Imagine a feather moving in air compared to a rock.
But me saying any of this amounts to nothing without getting into fluid dynamics, and I don’t want to start googling a lot of stuff.
Even if bacteria divide into two camps, those that photosynthesize and sessile and those who are heterotrophs and mobile (which is not true because euglena has both a chloroplast and a flagella, but that may be a rare case scenario, anyway, let’s move on) the macroscopic creatures that evolve from them don’t have to have the same dichotomy. An animal may get the photosynthesis gene with horizontal gene transfer like the insect acyrthosiphon pisum, a plant animal hybrid can arise with symbiosis like in photosynthetic jellyfish and the salamander, or some plants which used to be sessile may start moving and fill animal niches without losing photosynthesis. As flagellas and cilias aren’t used in the macroscopic world for movement, both animals and plants should have been able to evolve movement independently. (I’ll get back to this in (11))
Note that most of the biomass in an ecosystem is made up of plants, animals are endemic compared to them. If every plant was able to become an animal, animals would face a lot of competition. Think of how all the south american animals went extinct when it got connected to a larger biogeographic realm*. I don’t think the animals would survive the niche competition with the plants (competitive exclusion principle [1]). We’d see creatures constantly moving up the trophic level, as the apex predators go extinct and get replaced by the descendants of herbivores and later the photosynthesizers. I am surprised noone called this the “animals are still here paradox. It is a nice question to ask.
There are plants which lost photosynthesis (the parasitic plants), but there aren’t ones which started moving fast, which leads me to think there are other problems.
(3) It takes too many branches to support all those leaves, you’d essentially become a tree (true, but that doesn’t prevent mixotrophy)
How can you create enough surface area so that you can feed your warm blooded lifestyle, and the very expensive brain? Easy, you don’t.
This may come off as changing the problem, but an animal that gets only some of its energy from the sun is still an animal plant hybrid[2]
I first thought that the plant animal hybrid may have skin extensions to increase the surface area. That may have some problems. First, those extensions would need to be connected to the rest of the body with blood vessels, so you couldn’t bend it and prevent blood flow to that tissue for a long time. Also if a predator was following you, it could grab it and pull you. If it wasn’t that strong, it could tear. Being dragged on the ground could also necessitate constant regeneration. If the contribution of that cloak to the rest of the organism is very little, getting rid of that would be ideal.
But, even without a cloak, just replacing the skin with one that has chlorophyl would be useful. It doesn’t have to supply you with all the energy you need. Humans have 38% of the surface area required to feed them, assuming half of it is in the wrong side of the body, it becomes 19%. If there was a mutation that caused us to get 19% more energy from the food we eat, that mutation would definitely be selected. The same is true for photosynthetic skin. It is basically a backpack that gives sandwiches, allowing you to survive longer periods of famine.
And yes, carnivores don’t keep a very long intestine like herbivores and don’t eat grass on their spare time, but 19% sounds like a good percentage and being under the sun doesn’t interfere with other heterotrophic activities.
The ecologic consequences
(4) Reduced evolutionary pressures would make mixotrophs uncompetitive against heterortophs(i am not sure)
Here is a silly sounding idea. Photosynthesis is too good to have.
Imagine there are two patches, A and B. In patch A, the animals can do photosynthesis, if they start starving, they start hibernating and only consuming sunlight. Because of this laziness, they haven’t even evolved legs, they move like snails. In patch B, the animals can’t do photosynthesis, when they start starving, their lives are at stake, so they evolve all types of adaptations to survive. When patches A and B combine, the animals of B, having better adaptations, drive the animals of A extinct.
The problem with this line of reasoning is that it can apply to all types adaptations, not just photosynthesis. We don’t lack spleens because that would cause us to have better kidneys. Beneficial traits do get selected.
(5) If plant animal hybrids existed, plants would go extinct, and the hybrids would become the only plants, lowering the biomass of everyone above them, so no intelligence (depends on the planet size and how much energy plants use)
Imagine you are a photosynthetic goat. You climbed a tree, keeping it under your shadow. The difference between you is that both of you can do photosynthesis, but the energy you both get only goes to you.
Normally, you can’t cause a species to go extinct by hunting it too much, because lowering its population would cause you to starve, you would end up with lotka-volterra oscilations in population. A species can only go extinct if another species vies for the same niche and is more succesful. But if herbivores could also do photosynthesis, they would have the ability of driving plants extinct. This wouldn’t be the case for kleptoplasts, because they are still dependent on plants for photosynthesis.
In fact, you can say this already happened, as corals are more widespread than kelp or sea grass in some environments*. But corals are animals that did this while they were still sessile heterotrophs, and that isn’t what I want to talk about.
What if a mobile animal became the primary producer? First of all, there is a benefit to movement for plants, that is reproduction. We can observe this from the photosynthetic jellyfish, which has a mobile phase in its lifecycle for reproduction called the medusa and a sessile phase called the poly, oddly enough, the photosynthesis occurs in the mobile phase. I also want to limit this discussion to the seabed that is illuminated or the land.
Oher than reproduction, is there a benefit to movement? I previously thought there wouldn’t be.
Ignore the weight, it is negligible. But there is another problem with that. If you are a heterotroph trying to hunt a mixotroph, it isn’t you who has the advantage. The mixotroph can store as much energy as you (remember that plants also store oil in their seeds, which is a place that require compact energy storage), it can run as fast and as long as you. But it also has sun as a replenishing energy source. So the mixotroph can afford to keep running away from the heterotroph no matter how costly it is, because in the end, the heterotroph starves, not the mixotroph. Building a castle isn’t necessary.
But also not impossible. A tree could have arms, wielding a bony sword against a pack of violent herbivores in a scene that looks like a siege, completely different from the monotonous life of a goat. In fact this already happened.
It happened via a symbiosis between a plant and an animal. The fact that plants generate enough calories for movement, but why that movement is used against them is what I am questioning.
But let’s get back to the creatures that move all of their bodies. A mixotroph doesn’t just compete with heterotrophs. It also competes with autotrophs, because it doesn’t get all of its energy from the sun. All of the herbivores which would normally eat the mixotroph may give up and just start eating the plants, but the energy surplus of the mixotroph also gives it an advantage in foraging for plants, or just surviving famines, as I said before. The evolution of the first mixotroph may cause the extinction of both the plants and the animals!
Am I overreacting? Can mixotrophs coexist with heterotrophs just like how omnivory didn’t cause the extinction of all carnivores? I‘d say it I’m not overreacting . Adding photosynthetic skin to a heterotroph doesn’t have to change anything fundamental with it.
So what happens shortly after the extinction? Mixotrophs would be the only creatures around and they wouldn’t have a reason to move (and maybe can’t) all the time, so they would mostly be sessile. But they would be able to move. Imagine you land in an alien planet, but the forest starts running away from you.
I just noticed someone has to have roots to get water and nitrogen from the ground with roots, so the extinctions wouldn’t happen, or depend on if those stuff can be obtained another way. There would at least be decomposers or scavengers living under the ground which can’t do photosynthesis.
What would an ecosystem with more mobile primary producers be like? Since they spend more of the energy they produce, the higher trophic levels would receive less energy, and have less bimass (even if they can also do photosynthesis, because the total amount of sunlight the planet received didn’t change)
What does this say about intelligence? I still think innovation still requires a lifestyle filled with hardships. Humans were hypercarnivores for 2 million years, meanwhile the ants which had farming before us didn’t evolve intelligence.
(6) The mobility of plants would result in low genetic diversity and extinction (i am not sure)
Theoretically, only a single creature should be able to exist in a single niche, but that isn’t observed in planktons. Why?
A solution given to that is this.
If heterotrophs became mixotrophs, would they be able to invade each others locations, resulting in a single niche?
Less diversity in the primary producers could lead to less diversity in consumers (those that mostly consume). A niche that resulted in the evolution of humans may not appear. And what happens if all of that small number of species go extinct in a mass extinction, because a creature with the right adaptations didn’t evolve due to a lack of diversity? We may be lucky that earth didn’t have mobile plants.
Miscellaneous
(7) The ancestors of animals couldn’t photosynthesize (true, but what about alien worlds?)
If the first animals evolved below the photic zone, they couldn’t do photosynthesis. But there may be planets in the galaxy with only shallow seas.
(8) It takes too much space in the genome (probably not)
Dna requires compounds to build too. A cell with a larger dna may need more time to divide, which means slower growth and tissue repair. On earth, polyploidy seems to be common in plants*, 30 to 80% of the current plant species are polyploid. Does this suggest a preference for smaller genomes in animals?
But also, there is the g value paradox*, organisms tend to carry a way longer dna than they have to. I don’t think “trying to have too many things all at once” is the real reason for not having photosynthesis. And also, acyrthosiphon pisum is still around.
(9) Life is too short (wrong)
Building the photosynthesizing tissue could pay off in the long run, but if you just want to grow as fast as possible and reproduce as fast as possible, why even bother to build photosynthetic tissue?
This seems to explain the lack of mixotrophs without being an explanation that would make it seem like kleptoplasty shouldn’t exist. But not all animals live fast die young.
This explanation would also not work for any creature that looks after its young.
But maybe there isn’t a single reason mixotrophy isn’t common. Maybe it’s the little reasons that add up.
(10) What are the chances of photosynthesis and mobility evolving on the same organism? (depends on the probabilities, also horizontal gene transfer exists)
The oriental hornet is able to do some amount of photosynthesis, without the help of a plant species like kleptoplasts, photosyntetic jellyfish and the spotted salamander . Maybe this could be considered more similar to how we make vitamin d.
But the efficiency of the molecule it uses for photosynthesis, xanthopterin, is less than chlorophy*.
Maybe, instead of “why can’t animals photosynthesize”, we should ask the questions “why are there animals” and “why is there photosynthesis?”. The plants on earth may have not discovered chlorophyl and they would never have a high enough biomass for supporting a species like humans. Animals are also rare.
Maybe the real reason behind a lack of moving plants is because of bad luck. Maybe every branch of life experimented with photosynthesis, but one which succeeding in it was sessile. Any branch of life could have become mobile, but it wasn’t the plants.
But they can still end up in the same creature, as in the case of acyrthosiphon pisum.
The skin question
(11) You can’t make it into a skin (speculative)
Cnidarians are simple creatures, some of them have a mobile phase in their lifecycle and carry symbiont algae. Maybe, our ancestors also had a similar bodyplan, but they didn’t turn their symbiotic algae, if they had any, into a photosynthetic skin.
Animal/plant cooperation has evolved again though. The spotted salamanders take the algae inside their cells, while the kleptoplasts kill the cells, only take the chloroplasts. Chloroplasts on their own can only survive 9 months, but taking the cell as a whole may last as long as it needs
The spotted salamander lays its eggs on low oxygen ponds and uses the algae for the oxygen it generates. But it could have also used it as a “chloroplast that works” and used it for generating some energy.
There is a theory that different species can become a single species
If what’s theorised in wikipedia is true and the reproductive issue can be solved, then I think the photosynthetic jellyfish and salamander (they started later than the first life, but earth is habitable for one more billion year) could incorporate the photosynthetic species into their bodies and modify it into different tissues like a new germ layer.
But having some algae swimming between your cells or a plant spreading roots inside your body (you plant it on every egg) can also work.
Also, acyrthosiphon pisum exists.
(12) Chlorophyl/plast is often lost, and not gained back (could be the real issue)
If there were forest earth events in the past, like snowball earth, photosynthesis may have made less sense for animals (it is shadow everywhere). Mobile mixotrophy would normally be selected, but when chlorophyl is lost, it takes a very long time to evolve again, and maybe it doesn’t.
Other reasons for losing photosynthesis could be, constantly diving deep or going into the caves, lack of sunlight after impact or volcanism events, going nocturnal, evolving opaque body covering and entering environments the camouflage in which requires a color other than the color of the photosynthetic molecule. These reasons don’t make mixotrophy impossible. And if photosynthesis (or mobility) is lost, it can also be regained with atavism. But if it is completely gone, then that may stuck. It is known that ecosystems without mixotrophy can exist.
Related: But radiotrophy takes a shorter time to reevolve. All mushrooms used to have a radiotrophic ancestor.
Maybe they were using the more abundant UV light before the great oxidation created the ozone layer. When humans came with their nuclear reactors a short time ago, the mushrooms increased their melanin and started doing radiosynthesis again. There aren’t mobile radiotrophs around right now, but animals have melanin too, so who knows. Excited for Mars, anybody?
(13) Exoskeletons or fur is common, preventing photosynthetic skin (inconclusive)
Fun fact: sloths grow algae in their fur.
But they don’t have an Obligate symbiosis. The algae doesn’t get minarels and nutrients from the sloths body, and the sloth doesn’t receive calories from its skin.
Exoskeletons evolved before the endoskeleton. Trilobites couldn’t have been mixotrophic unless they had a long tongue. Can moss grow on a moving surface? I don’t know I am gonna call this inconclusive. Most fur doesn’t have algae.
Promising thoughts
(14) Plant cells weren’t flexible (if this is a trend, it could be the real issue)
If endosymbiosis is rare, not all branches of life may develop photosynthesis. But why didn’t any plant on earth became mobile? The reason may be because they can’t.
Venus fly trappers don’t have a free moving life stage, because they can’t evolve a tissue like muscles even if they wanted to.
Maybe it is a coincidence that earth doesn’t have photosynthetic animals, or maybe the photosynthesizers tend to have high HP cell walls, and can’t get rid of it to become mobile.
(15) If a drawback didn’t exist, acyrthosiphon pisum would be more successful (probably true)
It is exactly the creature that I am saying should exist, and be the norm. And it doesn’t suffer from the problem with plant cells. Granted, it is still soft locked to small sizes, because it doesn’t have lungs. But photosynthesis should give its descendants the advantage to fill all the other insect niches.
It also doesn’t suffer from the musclelessness problem of plants.
It is currently only 4 mm’s long. It has symbiont bacteria, but doesn’t need that to make its photosynthetic pigment. Wiki says
but this* website says there are also green versions of this insect, which I assume means chlorophyl, the best pigment known to nature. The endosymbiont bacteria of this insect is associated with plant viruses
they had this symbiosis for 160 to 280 million years. So anytime now. Mixotrophic insects can invade the planet.
Voting time
Whats your favorite solution to the lack of abundance of plant-animal hybrids observed by humans?
- Its too heavy
- 19% isn’t worth it
- One of the ecologic theories
- It just didn’t evolve, due to luck
- It’s the little reasons that add up
- You can’t incorporate a photosynthetic species into your body
- Chlorophyl often lost, not gained back
- Slippery fur syndrome
- Plant cells aren’t flexible
- Something else
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voters
Which replaces which?
- Plants become mobile and replace animals
- Animals gain photosenthesis and replace plants
- Both can happen, neither one would be fully replaced
- First, the animals replace because they had an arms race forcing them too evolve better tissues, but after that, it is a numbers game so plants start replacing
- Nothing replaces anything
0
voters
You imagine the most common sight in the galaxy to be
- A segregation between plants and animals
- Trees with bony swords
- Most common trophy is mixotroph
0
voters
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Not when you could instead evolve something that allows you to better escape predators or that allows you to acquire a more energy dense resource.
That’s just the weight of the leaves, but the leaves will also need a structure that supports them and that spreads them so that each leave will be able to acquire sunlight.
But I do agree that the “chloroplasts weights too much” is wrong.
Is not a paradox, animals already have all the adaptations for mobility while plants don’t, it is impossible for a plant to evolve mobility because animals would outcompete it from the start.
The type of mixotroph you are proposing would be unable to outcompete either plants or animals so it’s irrelevant, therefore also going against point 5.
They wouldn’t, because again, your mixotroph would be unable to use photosyntesis to sustain itself.
The photosynthesis would just slightly increase the time it can go without eating but nothing more, it still depends on plants as a form of primary energy source.
Also, you are forgetting about the materials that the herbivore needs to actually grow which they need to take from plants.
That’s not how it works thought, again, the mixotroph would not be able to sustain itselft using photosynthesis alone.
Also, your point completely ignores how endurance actually works, energy only makes a small part in it, endurance is mainly about your capability of preventing overheating.
No, your mixotroph would be unable to survive a famine that is long enough to kill a significant portion of other herbivore populations.
They wouldn’t be able to compete with plants (completely different niches) and if plants were to go extinct they would go extinct too.
They also would be unable to compete with heterotrophs and even if they were predation exists.
This makes no sense.
Irrelevant, in real life it isn’t about the presence of light or not, it’s about endosymbiosis.
Plants evolved after animals, they inherited mitochondria from their heterotrophic ancestors and then did endosymbiosis with proto-chloroplasts.
And no, Horizontal Gene Transfer won’t do anything since it’s endosymbiosis, the organism itself is incapable of creating chloroplasts because choloroplasts are technically another organism and you cant produce them on your own.
No it wouldn’t, and that they had the symbiosis for more than 100 million years is evidence of that.
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