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developing a species of seal based merfolk

Saproxylic

New Member
Hello! Newbie here, greetings!

I haven't been seriously writing for a good while, because life happens, but since I have been bedridden for a few days, I picked up a mental exercise of creating a fictional species of merpeople that would seem somewhat believable to me. The whole blob of text got kinda large, and as my head is fuzzy with fever, i kinda failed to shorten it,I will try a shorter version, but there are more details in the large blob

What I would like you to help me with is mostly asking questions about the said species and things related to it, so I can cover previously overlooked aspects, or pointing out possible issues that need to be adressed.

TLDR:
There is no significant magic involved.
This species is a placental mammal with all the consequences.
Resembles a seal with human like arms, hands, shoulders and some humanoid facial features.
Omnivore, but most of the calories come from fish, shellfish and other marine animals.
Nomadic, travels around the ocean following a circular current, one cycle takes a year.
Breeds in a synchronized manner, so all pups are born at the same time and geographically the same place every year.
They have a language, which is basically a hand based sign language, but they do vocalize to express emotional state or emphasis.
They make basic stone age tools, but don't know fire, however as they are nomadic, they don't accumulate a lot of belongings.
They have a male to female ratio close to 1 : 3
They live in pods of 70-90 somewhat related individuals.
They mate for life and have a polygynous family model, a male forming a family with a full set of sisters (2-4 usually).

The long and painful bit: if you really enjoy reading half baked mashup of facts

Placental mammals. They have lungs, breathe air and need to surface to breathe.

The bottom part looks like that of a Phocidae seal, the top part is more or less humanoid, but of more toddler like proportions, short chubby arms, lots of subcutaneous fat but the head isn’t as oversized as toddlers. Hands are relatively large compared to arm lenght, long fleshy fingers, opposable thumbs but instead of flat nails, short stubby dog like claws. Necks are pretty chubby as well. They have a bit of a muzzle going on instead of human protruding nose so nostrils are somewhat forward pointed, and they can close them when diving, but lips are pretty human looking. Eyes are visually similar to human eyes, and have third eyelid like some marine mammals and very long stiff eyelashes and some long hairs for eyebrows they use as sensory whiskers. They have modiefied tear glands that excrete the excess salt they consume through diet and drinking sea water. Their tail part is covered in short fur, the arms, belly and face are bare, the head, back of the neck and between shoulderblades has pretty long, rough hair. Urinary, anal and genital openings are located ventraly the same place where they would be on a seal. Male bits in the rest state retract inside the body. They have carnivore type incisors and canines, but strong chunky molars with sharp edges

They are opportunistic omnivores, main part of their diet is fish, crabs and shellfish, which explains their carnivore teeth. They will however eat certain types of seaweed like bladderwrack, ulvas and other nutritios ones, and when ashore they will eat eggs and baby birds that nest on the shore if they find any and land plants that they find palatable (though it’s a rare occasion)

They are nomadic and follow warm circular currents in the ocean, taking a year to complete a circle. For about three months in winter they take residence in warm coral atolls and tropical islands near equator, as the weather gets warmer they migrate towards pole reaching the furthest point in mid summer and heading back as the weather turns to fall side.

The pregnancy is about eleven months long, so the mating will occour around the middle of the time they are settled in the atoll and the young are born soon after arriving at the atoll. The pups are born reasonably developed physically and will grow very fast during the first three months of their life gaining a lot of blubber and swimming skills from the diet of very rich milk females secrete in their mammary glands. There will usually be just one pup in the litter, and females have two nipples.

They have intelligence compared to that of humans, but are far behind technology-wise. They are not using human type of speach, they can make a wide variety of noises using their vocal cords, but they use audiable noises only as expressions of emotions, not as words with defined meanings. For complex comunication they use a sign language using their hands similar to ones used by the deaf community.

Merfolk travel in clans of 70-90 people. The ratio or males to females is roughly 1:3 in this species. This leads to a polygynous family model. A merman after reaching complete sexual and social maturity (20-25 years of age) will leave his clan and join another one where he will be looking for mates. The Merfolk mate for life, and traditionally a merman will chose a desirable family with the eldest daughter who is sexually and socially of the right age (roughly 17-18 years old usually) and get wed to that family, meaning that he will become a husband not only to the eldest daughter but, once her younger sisters reach maturity, also to all of them.

Each merfolk female will usually give birth to 3-4 pups in her lifetime, each of them about 3 years apart (they will continue to breastfeed for about two years, that prevents them from getting pregnant earlier), as pregnancies are hard on them.

Thy will give birth once they reach the atoll, labor is easier than that of a human because of different pelvic structure, but harder than for seals as the babies have large heads and wide shoulders. The pups have some basic swimming reflexes as soon as they are born, but their hand use is comparable to a human infant. In the first three months they gain body size, weight and swimming ability really fast, so after the merfolk leave the atoll to go on their annual migration they are able to keep up with the clan with relatively little assistance, but their cognitive abilities an hand use is still very limited, they do recognize family members and do not venture away from them and express various emotions vocally, but are usually unable to sign coherently, although they might be trying to imitate adults signing (in a way human babies babble).

From here on their cognitive and motor skill development will progress a lot like that of a human. Coherent use of separate words comes at the age of one, speech with correct grammar and full sentences at three, at the age of about five or six they start to pick up most of the useful adult survival skills like basics of toolmaking and other crafts, huntin of smaller prey, gathering food and materials. The females usually hit puberty at around 14 years of age, males a bit later.

Females come in heat only once a year, usually at the time the clan resides at the atoll, however the first few times coming in heat is irregular and happens at other parts of yearly cycle. A female is considered to be of an age suitable for marriage and childbearing only when she comes in heat during the correct mating season. A baby concieved outside of the mating season would be born while the clan is in transit an therefore woul be highly unlikely to survive, therefore mating outside the atoll is considered a taboo.

They have only crude stone age technology, making tools out of flint, clamshells and bone, and are skilled in knots and braiding. Net making is especially developed as they are both used to hunt and to make all kinds of bags and packs that allow to transport what little belongings they have. They also keep their hair braided or bunned and use their hairdos to store small objects that have to be accessable fast like a knife, awl, comb and such.
 
I'm a sucker for detailed believable approach to creatures like this.

Apologies if it's in your text and I missed it - but first questions are:
How long can they stay underwater both as young and as adults? Strikes mne that this is important and could pose a great tension device if it gets near the limit.
Do they have any form of farming (even something very loose like carrying stuff to new reefs to introduce new species there for the future (much a sailors did with goats).
How do they interact with other groups and with humans?
How tied are they to the sea?
Seals can stay out of water a long time - and are tollerent of fresh water more than marine cetaceans - are these the same?
 

Saproxylic

New Member
I'm a sucker for detailed believable approach to creatures like this.

Apologies if it's in your text and I missed it - but first questions are:
How long can they stay underwater both as young and as adults? Strikes mne that this is important and could pose a great tension device if it gets near the limit.
Do they have any form of farming (even something very loose like carrying stuff to new reefs to introduce new species there for the future (much a sailors did with goats).
How do they interact with other groups and with humans?
How tied are they to the sea?
Seals can stay out of water a long time - and are tollerent of fresh water more than marine cetaceans - are these the same?

Thanks, I'm a total sucker for details as well!

About the times spent underwater:

Well, let's not make them too extreme. I would say the total upper limit might be around 45 minutes if actively moving, they might get a few additional ones if they just have to stay still underwater. Maybe there are some badasses that can make it to a hour, but that's considered both very talented and very reckless. I guess most everyday level tasks should be organized so that no one has to stay underwater for longer than 30 minutes in a row, to give it a good safety margin. And around 15-20 minutes would be a pretty relaxed dive that does not require a lot of effort.
I'm not an expert in seal psychology, but I suppose holding breath requires attention, so I assume that the breath holding potential of pups is not only determined by physiology, but also by their age appropriate attention span. Newborn pups probably are very limited , but by the time they are 3 months old and have to head into sea, they are capable of 5-7 minutes (which I would think is the instinctive limit, everything above that requires some additional willpower, therefore extended diving is a learned skill), I suppose at the age around six they are expected to be able to do the 15-20 minute dives similar to adults, that allows them to be productive members of society and participate in underwater gathering, and around the onset of puberty their diving skills are comparable to average adult.

About farming:

Shellfish are one of their favourite foods, so they do take good care of existing established shellfish beds. They have a good idea of how much they can take without depleting the stores so much that there are less shellfish the next time they come around, they will remove/kill shellfish predators like starfish and predatory gastropods from the beds, for shellfish species like mussels, that require solid substrate, they might move rocks or driftwood to create suitable habitat for them.
I guess not all clans take care about shellfish though, it might be a skill some have, while some other groups rely more on hunting pelagic fish.

Interaction with other groups or humans:

I imagine each clan having it's own travel route and maybe a little different timing of their travel, even though the general current they follow is the same, each clan having their own favourite resting stops, hunting grounds, clam beds, little traditional detours, so I guess there is an occasional squabble if two clans suddenly happen to end up in the same resource rich spot at the same time, though as I see this as a very feminine society, the conflict solving would probably be more passive agressive or based on individual arguments then outright warfare. (Think annoying members of the other group till one group decides the resources are not worth the hassle and leaves)

Regarding humans. The fact that humans exist is a general knowledge, but their contacts are getting more and more limited as humanity develops. While humans had similar technology level to seal people, (aka stone age) there would have been even some trade between them, but as human technology developed, seal people got more and more distant from humans as they had less and less to offer each other, and with development of larger scale fishing, warfare on the water, seaside settlements that polluted water and depleted resources around them, seal people started actively avoiding humanity. Over the time only a few clans still visit a few primitive human communities briefly, but most seal people have never seen humans, and aren't really sure how intelligent humans are or how they live. Many human cultures over the time have completely forgotten the existance of seal people or consider them a myth.


How tied are they to the sea?

Well, theoretically provided food and drinking water they could survive out of water for a very long time, but they would not be comfortable. First of all, they aren't very good at cooling down in warm temperatures, so they would get uncomfortable in warm weather, indoors. Also efficient locomotion is an issue, so joint pain is possible, as well as bedsores on the tail part from constant sitting/laying on it. Also hygiene might pose a problem. For example their salt excreting tear glands might not drain as successfully as tears quickly evaporate creating crystals and gunk and irritation, also they would probably find it awkward to deal with bodily waste on land.

About fresh and salt water:

I think as they have salt excreting glands they do have a strong preference to oceanic salinity, living in freshwater environment would lead to them requiring a lot of extra salt in their diet to maintain normal blood sodium levels. It could have interesting ramifications, like ''estuary sickness''. Also, I suppose they would find freshwater disturbingly foul tasting (like humans find distilled water gross).

Huh, this was fun! Keep throwing questions at me!
 
It's unlikely there'd be a biological reason for a birth difference in the ratio of males to females (if we're following the believability route - I can't think of any that do this - differences in ratios are usually very minor).
Therefore a male to female ratio of 1:3 implies some form of combat between males. So either the excess males are killed in combat, are driven from the group (in which case they either live solitary lives, or form all male groups - both are common in mammal species).
Which is it?
 
Is there a monetary/resource reason for humans hunting seal people?
Of course they'd have blubber - all marine mammals do. It's even been suggested that human subcutaneous fat (along with other marine adaptations such as diving reflex, hair directions etc. c.f Aquatic ape theory) is the result of a semi-aquatic period of evolution.
But is there anything else about them other than their meet and blubber/oil that's a potential commodity for hunters?

You might also want to look at the 'theory' that the ancient god-like being from Babylonnia 'Oannes' was an aquatic alien very much on the lines you're describing.
(If you don't already know about him)
 

Ban

Troglodytic Trouvère
Article Team
Great, as if I wasn't already too focused on my own worldbuilding, here I find a compelling species made by someone else :) . Anyways, I see that you have gone in great detail on their physiology, but have you thought about their culture/cultures yet?

-Do they believe in something divine, such as a god, gods, ancestors, spirits? If so, in what form do they practise this.
-Does class distinction/hierarchy exist in their clans? If so, who holds the power and how are different classes distinguished from eachother. What rights do the leaders hold.
-Do they have names? Who names who and when.
-Are there rites of passage?
-Do they wear clothes or decorate themselves in any way?
-What is considered taboo and what is sacred?
-Do they appreciate stories and legends like we humans do?
 

Ban

Troglodytic Trouvère
Article Team
It's unlikely there'd be a biological reason for a birth difference in the ratio of males to females (if we're following the believability route - I can't think of any that do this - differences in ratios are usually very minor).
Therefore a male to female ratio of 1:3 implies some form of combat between males. So either the excess males are killed in combat, are driven from the group (in which case they either live solitary lives, or form all male groups - both are common in mammal species).
Which is it?

Maybe half the embryos suffer from a recessive gene tied to the X-chromosomes which has the potential to kill the embryo if it becomes the dominant genotype? So half the male embryos die, but only a fourth of the females. I haven't had biology in a while though so I wouldn't know how this gene could potentially survive in a species if all the carriers die.
 
Maybe half the embryos suffer from a recessive gene tied to the X-chromosomes which has the potential to kill the embryo if it becomes the dominant genotype? So half the male embryos die, but only a fourth of the females. I haven't had biology in a while though so I wouldn't know how this gene could potentially survive in a species if all the carriers die.

An interesting thought. Recessives just hang around and can remain in the population forever really as they're only expressed when an individual has two copies of the recessive gene (or 1 if it's on the x chromosome).

That 2/3 of males die means that the gene would have to have roughly that chance of occuring in the female population. Which is high, but not unreasonable.
But what would the selection pressure be to maintain a clearly deleterious gene in such a high percentage? Perhaps it confers some other advantage (especially in the female) - such as that for sickle cell anemia which confers protection against malaria. The affect on males is a side product?
 
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Hi,

No need to involve killing of embryos in vitro to explain sexual gender ratios. There are many animal species that have less males than females and vice versa simply through genetic sex determination systems.

The selkies question Butterfly asked interests me. Mostly because they are a were species - seal / human.

My thought would be that interactions between your species and humans would be problematic without such a concept - simply because your merfolk areadapted to living at sea. That means why should they know how to make a fire? - fire doesn't burn in water. Why should they understand speech? - their ears / hearing and vocal apparatus should be designed for underwater communication. Ever tried to understand what people are saying when you're under water? It doesn't work well. And you can't speak at all. If you're going to have them capable to interacting with humans then I think you need to have some reason why they spend a lot of time out of the water.

Cheers, Greg.
 
Hi,

No need to involve killing of embryos in vitro to explain sexual gender ratios. There are many animal species that have less males than females and vice versa simply through genetic sex determination systems.

There are - but they're not mammals and then it's often down to temperature of incubation (its quite frequent with reptiles and birds).
There are some studies on mammals (and some on seals - in particular elephant seals) that show some variation in sex ratios - but it's tied to water temperature - so probably has the same biological root cause.
Normally the change is relatively small - and can make either sex more numerous not just one.
 
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