#mermaid anatomy

[drferox]

Fantasy Biology: Monotreme Mermaid

The concept of a mermaid, a pretty lady up top and a fish down below, is a strange biological idea. Another bizarre biological concept in the monotreme, but these creatures are actually real. So why not combine the two?

Monotremes, of which only echidnas and platypus survive today, are so biologically unique that they defied belief when Europeans first came across them.Some of he mix of features monotremes possess include:

Reptile-like skeleton

Hair

Milk production but no nipple

Lay eggs

Toothless adults (modern species)

Electroreception

Venom spurs

That’s a lot for us to work with while making our monotreme mermaid.

Let’s start with milk, because there is a long standing question of “Why do mermaids have boobs if they don’t lactate?” that constantly needs addressing. Monotremes do produce milk, but they do not have nipples. They either sweat milk onto a bald patch of skin, or into a twisted tuft of fur that the offspring suckle on. Modern monotremes don’t have massive mammary glands, so it’s unlikely for them to have hugely developed mammary architecture. They are more likely to have a diffuse swelling in the region.

Monotremes definitely have hair, and while it’s certainly possible for hem to have the long, flowing locks mermaids are often depicted with, they are also likely to have tufts of hair as nipples or consistent, short hair all over their back and back of their arms, leaving only their underside, face and tail bare.

The most distinguishing feature of monotremes is that these hairy little critters lay eggs. These are air breathing species, so their eggs need to remain in air, not submerged. While terrestrial monotremes do have a pouch, that’s not useful at all if you’re swimming all the time. The most logical solution I can think of for this is to either have them make burrows to hide their eggs in, like the platypus, or to bury them on shorelines like sea turtles do.

Monotremes do exhibit maternal care, otherwise why bother having the milk, so they can’t reasonably produce hundreds of offspring each, but they can certainly return to care for them and may produce up to a few dozen each. Think of mumma crocs guarding and protecting their young

Living monotremes species have can have a venom spur, which is actually a modified sweat gland again. This is positioned on the hind leg of male platypus, but you could put them anywhere on your monotreme maid, especially if their hind limbs have evolved like a seal skeleton. These mermaids may have barbs, venomous or not, anywhere and everywhere, like our friend the echidna.

The modern surviving monotreme species all have electroreception in their mouth/jaw and all lack teeth as adults. These two traits are likely related. It wouldn’t bend reality any more than it’s already been bent to allow your merfolk to have teeth, but they probably don’t have eletroreceptin at the same time. This would depend on what diet you’re expecting these creatures to eat.

So with this food for thought, here are two possible variants of the monotreme mermaid you could make.

Saltwater: The is larger species spends most of its adult like in the ocean, scavenging crustaceans and molluscs. They are covered in velvet-like fur interspersed with small venomous barbs running down their sides and tail. These barbs are brightly coloured in the juveniles, but fade with age and size. This species will swim up river to lay their eggs in the banks of estuaries, but don’t wander far until their young have hatched. A social species, an adult will remain with the newly hatched young until they have enough lung capacity for longer swims, with other adults regularly returning with food or to switch positions.

Freshwater: The smaller species is usually solitary, though daughters may remain with their mothers in hard years. They are extremely reclusive and nocturnal, making them hard to discover. They dig burrows with underwater entrances on river banks to lay 2 or 3 eggs, and mostly hunt small bottom dwelling prey in the rivers using electroreception. Their bellies are bare to aid their sensitivity, and instead of teeth they have hard, rubbery gum ridges which are extremely sensitive. Their legs are better developed than their oceanic cousins, and will sometimes be seen crossing land to get to a new water source.

Species for the Fantasy Biology series are chosen by my supporters on Patreon. From as little as $1 a month gain access to polls, sneak peeks and other rewards.

[shirecorn]

Since your merpeople are descended from fish, do they have pelvises? Are they able to assume a "sitting" position?

They do not have human pelvises, but rather they have operculum and preoperculum that rest in the hip area.

This is a very old drawing so I might update it in the future.

Technically they really should not have a great deal of movement in the area (certainly not 90+ degrees) but I choose to let them bend however they want as an artistic decision. Some of my choices are "I haven't figured out the specifics of how this works but I will one day" and others are "I have figured out that this is impossible and chosen to ignore that fact"

If they do assume a sort of sitting posture, they usually use one of both arms to support their torso and not put all the weight on the hips. So they form a tripod of weight distribution and balance.

If they sat on their tail only, they would likely fall over, as it's not built for that.

While underwater, sitting is less about putting weight somewhere, and more about managing buoyancy. Mermaid swim bladders (and almost nothing else) are in the humanoid ribcage area, so whenever they are at rest, they will automatically bob into an upright position. So "sitting" on the ocean floor is less about propping their torso up, as it is about controlling their swim bladder to be neutrally buoyant so they don't float away.

Only mermaids without swim bladders (be it pathology or evolution) have to worry about weight while resting on the ocean floor. Above the surface, however, things get tricky.

[vampboykaz]

What’s this?? More fun species concepts??

Again this isn’t representative of this species as a whole, this is just my version of them for something I’m writing and I wanted to share it with y’all!

Merfolk and Sirens!

Merfolk and Sirens are very similar, merfolk just live in shallow water and sirens live in much deeper water! They’re the same biologically and are compatible for reproductive purposes. If they live together their territory’s tend to intersect in kelp forests! While it’s not common for them to be mates, it’s not impossible!

Their tails can mimic any marine species! Sharks, whales, fish, etc! But they aren’t actually related to these creatures, it’s just imitation! Their tails are also incredibly heavy, often weighing upwards of 200 pounds. They also aren’t mammals! Their upper half looks human but they don’t have nipples or a belly button, they also lay eggs!

Merfolk also don’t have male or female like we do, they all have both parts! They do have gender though, but it’s in presentation not related to parts at all!

Unlike angels they are not compatible with humans! In terms of making a child at least. They can absolutely have sex, it just wouldn’t produce any offspring!

Their genitalia is more similar to humans than anything else in function, but isn’t quite the same. Their penis like appendage is long and thing, sort of tentacle like, much longer than a humans, 10-12 inches, but thinner. It essentially functions like a large ovipositor. They don’t really have anything like testicles, rather something more internal that holds eggs that they lay through the tentacle bit into the “female” part of their partner. The tentacle part remains inside them unless aroused, and under it is a part similar to a pussy, since the male part is what lays eggs, they don’t have any sort of menstruation. It’s just for holding eggs. The receiving partner carries the eggs for a little while and then lays them. Merfolk don’t care for their young so that’s pretty much it- they just leave them lmfao. Fish behavior

The eggs are marble sized and tend to somewhat match the color of the tail of the merfolk laying them.

Hopefully that makes sense- trying to explain how mermaid sex works lmfao

also if the eggs were laid inside a human absolutely nothing would happen and they wouldn’t be fertilized since it’s the female part of a mermaid that does the fertilization

Mermaid skin is also a lot thicker and rougher than human skin, but their underbelly tends to be really soft. Their internal temperature is also super high, not uncomfortably so, but warmer than a humans would be

[vcreatures]

Mermaids are high complex creatures. An anatomy that seemingly incorporates aspects found in both aquatic mammals and fish. Despite this vast dimorphism, the internal anatomy is largely shared amongst the varying species with some evolutionary adaptations that may be specie specific such as the Labyrinth Organ.

Bestiary log: The term mermaid, despite it’s intrinsic feminine connotation, holds no gender specific marker when discussed or noted. The vast majority of Mermaid, or Merfolk, species have both males and females. Some with obvious sexual dimorphism, others more subtle. However there are species that are hermaphroditic and even fewer that are single gendered, such as Tritons. 

[numberonetyrantwonderland]

Mermaid Anatomy?

So look. Recently hyperfixation of mine has been mermaids. I've been writing a story with a lovely mermaid that got me thinking. In this story, my mermaid has gills on her neck like a fishy, but still has a nose and lungs.

This got me thinking a lot about mermaid anatomy. They're part human, part fish. I'd imagine with gills they'd take oxygen from the water as a fish would, but with nose and lungs breathe air. It confused me quite a bit on how both those things could work and coexist internally.

Look, this is never going to be in my story, but I'm in too deep now. I need to know.

I did some research. Fish don't have lungs. Water enters their mouth and moves through their gills, oxygen seeps into the blood vessels there and carbon dioxide follows the water back out.

If a mermaid still has a human nose and lungs, well how would the body go about separating the two? Here's what I was thinking

Gills on the neck attach to the trachea and have a flap much like how we have whatever the hell it's called that blocks one tube when we eat or breathe. Under the water the mermaid breathes in the water and that flap opens and the gills work as it does on a fish. Above the water, when they breathe air, that flap closes and they proceed to breathe just as a human would.

That's how I imagine it would work anyways. I don't know if that's even physically possible, but blah who cares. It would have killed me if I hadn't figured out some way for it to work XD

[strawberico]

I've recently fallen back in love with merpeople mostly cuz I've been rewatching my favorite Barbie movies!!! 💋💋💋

This betta fish mermaid

Ik the pretty ones are male but I don't care I wanted to draw a pretty mermaid so ig she's trans💋

[walk-the-plank-the-what]

Would mermaids live like animals or do they have more structured society like humans? So maybe they live in underwater houses and stay “inside” more than they go outside? Bc they’re basically sentient people, and humans eventually went towards living inside and having societal structure, so if a merperson were captured and put in an aquarium with fish, that would be like putting a human in a forest enclosure with bugs and mice and stuff instead of a house with plumbing. And by the logic that they treat the rest of the ocean like ppl treat the earth, would they have pets? Bc they probably wouldn’t just have a slew of fish friends unless they were some kind of conservationist or something.

Also, I feel like merppl would definitely need plumbing bc otherwise they just breathe in their own nastiness all day

And maybe they prepare their food in a way comparable but different to how we cook food, so just throwing a few fish into their enclosure for them to eat is like if your captors handed you a live bird and expected you to swallow it whole

And if they do live in societies, idk if they would wear clothes or anything like that, but they would have to manufacture materials that don’t degrade underwater as easily, for both clothing and for buildings and tools, and would human captors be prepared to provide more of those if needed? Or they might just have blubber, or be cold blooded and so it’s meaningless for them to have heat insulation

Also, would they have copper-based blood instead of iron based blood like horseshoe crabs? Bc most fish have iron based blood anyway and bleed red, but idk the specific conditions that allowed for some animals to have copper-based blue blood

But maybe land is the only place sentient life like humans could form due to it being important to survival, bc in the ocean sentient life is mostly octopi or dolphins, and they didn’t need to evolve past that for survival so they didn’t, and so all these questions about if they would have inherited a need for societal structure and houses and clothes are meaningless.

[sadclownvibez]

gay mermaids cause i still can't focus on school

[albanenechi]

Drawing bases & pose references pt 83 🫶🌿💕

3 extra drawings for patrons!

[revretch]

I saw a post where someone interpreted a mermaid's lower half as being 100% accurate to fish anatomy and that bothered me because like

But if that's where you want your mermaid's butt to be, go on ahead

[gomzdrawfr]

cw: sea animal death

okok, I've never ran walked home this quick just for some doodles inspired by this and this (if you haven't already, go check it out)

tags u...@on-a-lucky-tide

[koifishanonymous]

@havanillas’s rtrn mermaid au has been giving me brainworms chat

[shirecorn]

@lux-lumen Mermaids don't need top surgery because they don't have any breast tissue!

The physical features that mimics human breasts are stretchy empty sacks that can be filled with water. They are deflated when swimming for better hydrodynamics, and can be flat or filled with water when at rest, depending on the mermaid's preference. All sexes of mermaids possess the pouches, their use has nothing to do with the mermaid's gender, nor their reproductive sex.

To learn more about this world, follow @worldofvonder

Originally, mermaids evolved to mimic the beauty standards of humans in their regions. But now, mermaids look however they want without caring how humans think they "should."

Some mermaids happen to fit modern human preferences, to the chagrin of insecure people everywhere. Though many humans and mermaids have successfully courted each other... They are still formidable predators with endless defense systems, should you overstep.

While not human, mermaids are still people. Treat them as such.

Now, do stop laughing.

[vikcacao]

Mergumi being a little shit bc Yuuji's and ass guy lmao

[bastart13]

How do you imagine hybrids work in love and legends? We've seen elf/humans.

So there are 6 different species and aside from the mermaids, they're all compatable to have children.

I headcanon life expectancy, colouration, and the shape of facial or body features to be gradient traits, so they pretty much randomly combine between the two parents like any other child

Magical traits are probably more binary. So a fairy hybrid child could inherit the eyes, wings, and/or sparkles, or none, with no middle ground. A demon hybrid will usually inherit a faded form of the markings, but they won't always be able to transform or earn horns. Dwarf hybrids might inherit the ability to echolocate vs just having larger ears.

If two species with strong magic have a child, they're more likely to inherit magical traits (e.g. elves and fairies with strong magic vs humans and dwarves with low magic)

Considering the domains are all friendly with each other, I imagine it's fairly common to have mixed ancestry and there's no real taboo aside from the grief of lifespan differences

[dangerdazee]

me wanting to do a full in-order rewatch

vs

my list of favorite episodes