being a comics fan is like i could give you some general information abt any given character but i'm not necessarily a scholar of theirs you would have to see a specialist to be sure. the same way like in a pinch a pediatrist could tell you you were having a heart attack but you probably want to follow up with a cardiologist
i will speak my incomprehensible truth for you my friend. bear with me here
im just saying its a huge missed opportunity to have a marine species and not take advantage of all the cool sex traits that exist there!!
With sequential gonosimulists, they start off as one sex then later transition to another. Sex that changes based on social role vacancies (clown fish, MtF) or size (asian sheepshead wrasse, FtM) or just whenever they want, however many times they want (broad barred goby, MtF or FtM) are all naturally occurring in marine life. And these are just a few examples. There are also synchronous gonosimulists, which have the ability to be both male and female at the same time (hamlet).
And applying these really cool systems to Atlanteans, you get to think about how this then creates gender within their society, and with that how society itself is shaped. The politics of Atlantis!!
I'll do an example. Let’s go the clown fish route. Stay with me here.
If the queen always transitions to a female to fulfill that role, what does that say about that given sex and their implications in society?
So let’s say Atlantas is run by a queen--and I’ll go off of prime earth lore here. If you’re queen, you've been a female or you’ve transitioned physiologically [maybe in this fantasy case, those in leadership/important roles (very lenient definition) become female, so its not a society of all males and then the queen]. Atlanna is queen. Cool and typical. Aquaman comics are about being an outsider and different, though. So then we have Arthur.
Ik with his prime earth origin, he’s half atlantean and raised on land, so maybe he just stays male even when being brought into leadership roles as a royal. This can be because his parents are so physiologically different, there could have been an impact that would effect this transitional trait, or maybe his time on land and being raised within a human culture has strengthened his own perceptions about his identity and what it means to be a leader, regardless of sex and gender. What would that mean for their society then, being ruled by a king? Could also have really interesting implications for Mera too, and can give her a lot of political power.
And if you want to stray from bloodline royalty and really lean into the clown fish model, that makes royal succession 100% identity-based. You don’t inherit the throne, you are biologically called to it by your social environment.
As for the case of both sexes being synchronous, that means maybe gender is based on something completely different (and I’m using gender here as like. Default pronoun-determiner. APAB,, assigned pronoun at birth lmao). The gender-determiner could be a different aspect of the body, like markings/colorings, or maybe echolocation frequencies/vocalizations. These can behave as secondary sex characteristic equivalents or as a mindful presentation choice. If it is a purposeful way of presenting oneself (having the ability to change colors or pitch/frequency to any of the genders and choosing a specific one), that would make gender in this society so incredibly fluid.
Maybe gender is removed from the body completely, with it being determined by the environment which you were born into. If a civilization is close enough to the surface for vegetation, light, tides, moon phases, etc., then maybe it’s determined by light phase, season, or what have you when you were born. And if you really want to stray from human classifications, maybe it’s a ton of different factors that make up gender. Season + day/night period + moon phase + tides, and some calculus is done to assign you a gender LMAOO. Social constructs can have whatever rules you make up <3
It’s also a real kicker for their infanticide survivors, given they wouldn’t know information about their birth and thus culturally removed from gender itself if they returned to Atlantis.
Also, given the variations in environments between different atlantean cities, its free world building—every city state is gonna have some variation of gender based on their sea, elevation levels, etc. Because factors like tide, moon phases, algae blooms, etc simply do not have significance for a city state in the deepest of ocean trenches. It gives Atlanteans all the more reason to not get along and be the isolationists they love to be LMAO
And there are cases where sex is decided by the environment, aka environmental sex determination (very literal name). Some reptiles are known for this one, where the sex of offspring is determined by environmental factors like temperature during development.
This has some interesting societal implications, because the parents (or maybe the government.. we know Atlanteans are weird about babies) would choose the sex of the child. Lots can be done with that premise.
And if sex doesn’t change, but instead Atlanteans have a make up like marine mammals where everything is internal, there would also be implications on gender and the body in their society! Sex assignment at birth would be more complex (if done at all), and regardless, no one would be able to tell by eye what a young child is just by seeing them out and about, so there’s a neutral gender for children prior to puberty.
With this, there’s an entire phase of childhood where everyone is treated the same regardless of sex, which definitely would have its impacts on gender and discrimination and perceived roles to grow into. There could be a stronger decoupling of sex and gender, and children would be raised with shared expectations and access. Or perhaps the opposite happens, where there is an increased pressure to abide by secondary traits once they present.
I just think it’s neat when different societies with entirely different physiologies are unknowable to one another and alien-feeling!!