#not the “i gave birth to you!!” talk | Explore Tumblr Posts and Blogs

rxttenfish · 2 months

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Pardon the question, but how do the reimagined merfolk reproduce? In MP I recall them saying that merfolk reproduce in a similar way to seahorses (may be a throwaway joke, but in any case) but the reimagined merfolk are obviously different from how they are in MP in many ways.

ah yes, one of those things that i've had worked out fully for forever but never made a dedicated post on it over here... at least partially because im suspicious of tumblr and its ability to nuke anything even frankly talking about sexual selection and reproductive methods of various animals, oops.

which is why this is going under a cut, oops. like i said, lots of frank discussion of sexual selection and the processes of it. im a nerd when it comes to this.

the first thing most humans would notice when looking upon a group of merfolk (of the same species), is a notable lack of dimorphism. there's no dramatic color shifts, no difference in size beyond usual distribution among a population, no odd behaviors, nothing to really sort them out from each other. this is a consistent theme among merfolk in general — while they continually get larger as they age (at a much slower rate than they did growing up, certainly, and not as dramatic as pop media might suggest this to be), it's still fairly close along the existing curve of height distribution, and usually the only real "tells" for an adult merfolk's age is that they get pitted and worn, a little like a statue slowly wearing down, or similar to the age of crocodilians.

which might be a little odd for these hypothetical humans looking onwards, even if they were already familiar enough to be able to tell merfolk facial features apart. even moreso because as frank as merfolk cultures usually are about sex and nudity taboos seem rare, all of their applicable anatomy is internal, so even seeing one entirely in the nude isn't enough to sex them.

the truth has to do with merfolk as a secondarily aquatic tetrapod. i've mentioned before that the early ancestors of merfolk were temnospondyls that responded to environmental stressors in their freshwater environments by being able to take advantage of a wide variety of environments. they have lungs and gills, meaning they can breathe on land very well if they need to move between pools and ponds, and they have gills to optimize their time spent underwater and not have to surface if the going is good underwater. even more than that, they developed both external gills and internal gills, meaning they could reap the benefits of both fast-moving and slow-moving water.

all of this is relevant, because to be exposed to all of these different environments and to be able to move between them when the going gets tough in one, means they had to make longer and longer treks over land. some were dependent on specific vernal pools that they would travel to to raise their young, but this also limited the areas in which they could live, and if those vernal pools dried up then they could not reproduce.

so these early-line temnospondyls made the same switch that other tetrapods have made, and switched to internal fertilization. this meant that, if they were to find another one of their species during their land-travels, they could mate and continue onwards, even being ready to lay eggs right at the moment they found the vernal pool, limiting the amount of time the offspring needed in the water.

however, they did still need vernal pools and water, and were very vulnerable in these stages. and with the existing push towards shorter and shorter time spent in the vernal pools, well, what if they just didn't bother with them at all? it'd put more stress on the parents, but they were already primed to be able to survive through these periods of stress, so it wouldn't be such a huge jump.

so the line that would eventually lead to merfolk and the leviathans both made the switch to live birth fairly early on in their history.

the rest that happens from there varies. this was a more diverse group, back in the day! there were many different species with many different methods for that live birth. some would continue just carrying the fertilized eggs to be dropped off in the next suitable pool they found, some developed them into tadpoles, some went through metamorphosis in the womb and popped out into the world as mini adults, some left spermatophores for others of their species to pick up, some developed evertable genitalia and went at it that way.

but another shift also happened early on in their evolutionary history. them being able to spread out so far and wide meant that there was a very low density of them in any given area, and these low numbers made them vulnerable. if there was high disparity in the proportion of sexes in any given area, they'd feel the effects of that quicker, and when they were already in competition over the same niches as other temnospondyls, crocodylomorphs, marine reptiles, and later early cetaceans, etc who dominated these niches, they were often kept at these lower population numbers.

which was about when these early-line temnospondyls also made the switch to a trioecious mating system.

this happened because sex determination in amphibians is already weird, so it wasn't too far of a leap for a mutation to arise which created fertile dual-sexed individuals. and these dual-sexed individuals had a lot of success under the niche they had already carved out! now, whenever they did find another member of their same species, it was guaranteed that they could mate with them, which meant that their populations were self-sustaining and stable on much lower numbers. due to how their dispersal already worked, inbreeding wasn't as much of a negative factor, and they were even more capable of making it through the disasters and ecological strain that had the other non-lissamphibia temnospondyls going extinct. they could eke out a living wherever they found it, make long traversals over land if they needed to seek out greener pastures, and they were able to sustain themselves in the background without needing as high of a density of themselves in any given spot.

like i said too - this was a diverse clade back in the day! and you ended up getting different variations on this. some species didn't have any dual-sexed individuals. some species had only dual-sexed individuals. some had only males and dual-sexed individuals, and some only females and the dual-sexed individuals, and all in various different proportions and numbers.

what matters here is that merfolk were a part of the line who had evertable internal genitalia, and who ended up entirely composed of these dual-sexed members, making them an entirely unisex species in the modern day.

(this is also where i butt in, to explain from an authorial perspective, this is me kinda... being sneaky with canon and how it tends to phrase things. yes, technically it is the male who gets pregnant with merfolk! but, also, so would females. because they don't have "male" or "female" in these strict terms, and any given individual to them has the potential to do both. this is something that i do a lot with the usual facts given to me by canon, where it's technically true, just because i like to be contrary about it and not take things in the most literal way. it's just what i find fun, i know some other people do it differently, and that's fine with me!)

what this means is that merfolk don't have a conception of "gender". it checks out with their social structure too, because if a merfolk's miivt'ia have a child, then it doesn't matter who actually physically created that child, said merfolk would still consider themselves their parent all the same. the reproductive unit is larger than a singular merfolk or even two merfolk, and at that point, even if they were bisex, then each grouping still has the same reproductive potential as any other.

what this means is that, when miranda describes herself as a princess or a girl or that the king is her dad or she has sisters — these are best seen as translation errors. to a merfolk, the concepts at play aren't gendered. they would not immediately identify themselves as male, they would not immediately identify themselves as female, they'd be very confused and would only get more confused as you tried to explain it to them. miranda describes herself as a princess and uses she/her because she was told that, for landfolk, everyone had to pick one of two and she had to just choose one. she picked "princess" and "girl" because one of the first things given to her as a way to learn english were fairytales, and she really ended up latching onto the princess characters in them.

in fact, this is why merfolk seem to be a little... reductive? when it comes to gender? as in, if you do take the time to explain it to them, you will have to explain it all. which means starting with gender relating to the different genitalia, and you have just told this hypothetical merfolk that it is important to landfolk, who will now operate under that assumption. they will not innately understand why landfolk care about this or all the distinctions thereof and certainly not the nuance of it, so they end up just going "okay, when this landfolk tells me this person is a girl, that must mean she is like this", and potentially getting frustrated when you tell them that that's wrong.

it can't even really work for royals, who do simplify parentage down to two people, and care a whole lot about who is related to whom. for royals in the current merkingdom, its primarily about attempting to preserve a specific lineage. because merfolk lineage is its own can of worms, they simplify - they take the current heir (one who has been groomed and taught how to behave as though emblematic of that lineage and has been guaranteed to have the strongest claim to it), and will find a suitable non-heir of another royal house, for whom they will forbid either of them to make kids with any other merfolk. this agreement is less like a marriage in the traditional sense, and more like the heir's house is briefly sponsoring the non-heir's house, sending extended political and economic benefits to the latter through this connection, in exchange for reinforcing the lineage of the heir and making it more potent, reinforcing their political ties.

this is to ensure that absolutely no other genetics can be involved and to contain the process. because this occurs by who-was-born-where, it also means that only the heir really matters in this ordeal. if the heir dies while the non-heir of the couple lives, and they already have had children, then the non-heir is "locked in" and cannot remarry, obliged to stay within the heir's house in their current position to ensure the current holders of the lineage are brought up and cared for properly. if the heir dies while the non-heir lives, and they have no children, then the non-heir is sent back to their prior family with no benefits, and the next heir is named as though the marriage never happened. if the non-heir dies while the heir lives, then they can remarry as they please, existing children or not. this is not especially popular, as the non-heir's family can accuse the heir's family of being unfair or snubbing them, but it is still perfectly legal and accepted.

for instance: the king, miranda's father, had to marry into the royal family. it was the queen, miranda's mother, who was the crown princess before miranda, and who is seen as passing her inheritance down onto miranda and the other three sisters. when the queen died, the king could not remarry. he was secure in his position as king, but any other marriages would not carry the lineage of the royal family, and at best he would be seen as trying to "dilute" that lineage.

in this setup, it's not all that important who is the donor party and who is the carrying party. either the inheritor or their partner can be the one carrying, so long as it's certain and guaranteed who the baby comes from and that this can be assured with certainty. usually it's agreed between the two of them for whatever reason, though the carrying partner does have a benefit in being a surefire way to prove that they are one of the parents, with zero doubt. inheritors will do this mostly to make their kids look the most "100% royal line, no doubts", but this can also go the opposite way, to cement it down to it being a specific line who carried them and to reinforce the political benefits their prior family enjoys from this arrangement.

which brings me back to merfolk genetics, and why this is so important for the royals to ensure they know exactly who made what!

which is to say, merfolk never opted for traditional sexual competition, and instead erred towards sperm competition.

early on in their lineage, they didn't have a lot of sexual dimorphism to begin with. they were already fairly widespread, and while gatherings around early vernal pools were a pressure towards sexual competition, after they stopped relying on vernal pools, the differences between the sexes became more of a hinderance than a benefit. why would they bother with any colorful spots or being extra big and bulky when you're not even around enough of your species for choice to be an issue? if you can find another one to begin with, then that's really all either of you need, and challenging each other just puts another bind on that low-population issue. they were all function, minimal fuss, beyond some general traits that were seen as markers of health.

even when the ancestors of merfolk first started forming their colonies along the coasts, they didn't change this. there wasn't an initial hierarchy laid out, they were just a large group of the same species arranged in the same area for the same purpose, and also maybe some protection by numbers. they did start to form the early groups that would later lead to the modern miivt'ia, and they started to primarily associate with those groups and socialize with them, which meant that when they wanted to find someone to mate with, that hunting group was always the first and the easiest to access.

why fight over mates in that situation? why compete? the health of the group starts to become directly correlated to the health of the individual, and you've already determined they all have good genes, or else they wouldn't be this beneficial to helping you hunt and survive and evade predation.

but this isn't to say competition isn't happening. there is still the slight edge that natural selection adds in, and with multiple matings between different individuals, the thing that gets selected upon is the sperm itself. faster sperm, ways to kill competetor's sperm, ways to suppress the immune system of the mating partner to ensure that sperm will take, more output, ways to remove competetor's sperm to begin with, etc etc etc. their internal genitals start to get bizarre, both for the sake of excluding saltwater intrusion as they get more and more aquatic, but also for the sake of this sperm competition. this system also means, not only do more matings occur right after each other, but more partners involved. the "default" evolutionary position for merfolk starts to look more and more like a clump of noodles, writhing around and over each other. sexual contact becomes a way to bond and to connect with someone primarily, and a means to reproduce secondarily. it's an easy way to solve problems and to get merfolk to make up, by them simply fucking it out and everyone feeling better for it.

which is where i can get into the actual mechanics of it all!

unfortunately this is also where i run out of steam (also am sick. that will do it too), so i'll absolutely have to make a part 2 to this... and also i'll make another post sharing a few old writings of mine on this topic.

someday i'll make like. a masterpost on merfolk reproduction and what's going on there, but like i said. sexual selection is one of those things my brain goes ham for and i looooove talking about all these additional little facts. like how merfolk pregnancies last 2 years (to match with other large marine predators), and that they're based off of both tiger sharks and the alpine salamander, the latter of which has the record for the longest pregnancy on the planet at up to five years :3

also read Bitch: On the Female of the Species by Lucy Cooke if this sounds interesting to you! and maybe listen to the episodes the Common Descent Podcast did on Live Birth and Milk!!!

#all the care guide says is 'biomass'#asks #fishyfishyfishtimes #pregnancy tw #reproduction tw #SO MUCH REPRODUCTION TALK #theres more too. ofc theres more. theres so much more.#im a freak about this. do you want to hear about the protein layers on their eggs.#do you want to hear about their regulatory genes regarding their gills #do you want to hear about how all of this ties into their culture and why their god of children and childbirth #is also the god of war and violence #i have too much of this. i need to be stopped.#also i thought it was funny if the non-mammalian species gave live birth #just because its so overlooked despite being remarkably common?#ill admit merfolk all being unisex and having no gender is the hand of god #just really wanting them to not have gender for Obvious Trans Reasons #but im having fun with it. im making it work. theyre getting weirder with it.#im having this not just be the author's fantasy and create problems too #(many problems. in fact. this might even be a theme of my writing or something)

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