What would mermaids, underwater weaponry and underwater farming look like if they evolved naturally?

i was talking with some friends on discord about what weapons mermaid cavemen would use and the topic of using blood to attract sharks and i was reminded of how we domesticated wolves mermaids in this world are just an alternate branch of homo sapiens that decided to hunt underwater and were forced to dress up as seals and learn to swim in fake tails and therefore are hiding from us so I'd also like to know if there is a mythical creature that could be a domesticated shark also what Fantastic Livestock would they have as well as how that would change if they were allowed to integrate with homo sapiens sapiens civilizations

Edited by Wild-Starfish on Apr 6th 2023 at 8:11:12 AM

Okay, so there are a few questions there:

1) As to weapons that might be used by pre-metal-use merfolk, I'd suggest that shark teeth might provide nice edges and points for knives and spears.

I'm not sure what spear-shafts might be crafted from, offhand—perhaps someone else will have a better idea.

2) As to a mythical creature that might represent a domesticated shark, hmm... That I don't know. But I leave the question stated as I have here for the convenience of other posters.

3) As to what Fantastic Livestock they might have, perhaps they might construct fish-pens of one sort or another. I could also perhaps see them domesticating octopuses. Kelp and the like might make for useful crops.

4) As to how their complement of Fantastic Livestock might change after integration with land-based humanity, perhaps they might start incorporating creatures or plants that are of interest to land-based humans but not to mer-humans.

Well, we already know what underwater hunting technology looks like: harpoons, both the handheld spear-like and the firing variety.

Melee fighting underwater is problematic because water resistance prevents quick rapid movements (at least compared to movement in air), so grappling and knife fighting styles will probably pre-dominate in any conflicts within Merman society.

But domestication is a huge, complicated topic that whole books have been written about. To make a good domesticated animal, a species must possess a combination of traits that make them useful to humans. Since you mention wolves, I assume that you are focused on hunting companions. Bear in mind that canines are naturally social, live in packs and develop close emotional bonds with their parents and siblings. Those traits make it easy to adopt them as puppies and integrate them into the human community (they basically behave toward their owners as if they regarded them as parents). They also have to be smart enough to be trained to undertake cooperative complex tasks along with their human companions.

Sharks fail on all these criteria, so I don't think domesticated sharks work out well, sorry. However, I have an equally cool substitute for you: dolphins and whales. They fulfill all the criteria I listed above. Dolphins are already cooperative pack hunters, adding humans to the mix should be pretty straightforward. Besides, they're cool: personally, if I had to go riding into battle on the back of a sea creature, I'd prefer an Orca or a Sperm Whale to any shark.

And if you need a cattle substitute, the obvious candidate is the Manatee. Fish can work if you are careful to pick the territorial ones, otherwise they need to travel farther than most water farms could extend. Few fish have any natural disposition to manage their waste dispersal or food supply, so the Mermen will have to do that for them (this challenge is what keeps sea farms from being commercially competitive today). Otherwise shellfish might be a good option.

Octupi make good pets.

good point about them being unlikely to develop metal I didn't think about that I should reiterate that they are marine mammals in this setting and not fish and therefore can use fire and I should mention that they actually do use fire to cook fish

I am curious: How do they use fire?

(I do imagine that, as an offshoot of humanity, they may have the advantage of having known about fire before moving to the waters.)

well they are the inspiration for both mermaid and selkie myths meaning they do still go on land even in modern times, as for they'd use fire so close to the shore I haven't really thought about that too much

I like the idea of domesticated manatees since they are going to need a blubber-like substance for their sealskin/mermaid tails

Okay, that seems like it could work! Perhaps they might build loose stone structures to shelter their fires from the wind and spray of the sea; little temporary ovens, in effect.

(Or not-so-temporary ones, if they return to the same places regularly.)

by the way would there be a biological difference between freshwater mermaids and saltwater mermaids?

Yes. Saltwater requires a different kidney function than freshwater. Skin and membranes too.

And body/blood chemistry. Humans for example are a “freshwater” species in the sense we’re not capable of drinking saltwater be it from saline lakes or the sea. Nor are we capable of swimming or immersing in it for super prolonged periods of time.

Because in a nutshell it dehydrates us. Pulls the clean water out of us.

The same happens to freshwater fish that are not tolerant of exposure to the ocean. They basically have all their water pulled out.

Sounds like a particularly cruel execution method.

They would look like sharks with laser beams on their heads.

so does that mean that saltwater mermaids would be able to drink saltwater? Also what would be a good reason for mermaids to have human like-hair and would they have blubber?

For the former, sexual selection might work—just as in a peacock's tail, the fact that it might be a disadvantage to survival may yet be outweighed if it's a sufficiently significant advantage to reproduction.

Otherwise, perhaps their hair is coloured in such a way as to provide camouflage?

For the latter, that might depend somewhat on where they live: the colder the waters, the more blubber they'd likely have, I daresay.

(Alternatively, they could be furred, which might speak to both questions.)

Actually, on second thought I don't think mermaids would have blubber because I just remembered that mermaids would wear clothes made of manatee hide. As for fur I don't like that idea for 2 reasons:

1. They're meant to be a Human Subspecies^note or i guess two since there'd have to be a dinstinction between saltwater and freshwater mermaids so they'd have to have reevolved fur.

2. I'd like to keep them true to Mermaid/Selkie myths which obviously didn't have fur.

That's fair!

Although to point 1, there is I think potential for past evolutionary traits to re-emerge should environmental pressure push for them—and it's not like humans have lost all of their fur.

But yes, if they have sufficient insulation by clothing, then that may obviate blubber or fur.

I'm not sure that clothing works well in cold water, but they might use it for their forays on land.

can you please explain the problems with clothes in cold water

Clothes provide warmth by creating a layer of warm air next to your skin, which insulates the body from the cold air outside the clothing. In water, the water will permeate the clothing (unless it is waterproof, like a scuba diver's wetsuit) and the cold water will end up in direct contact with the skin, eliminating most (though not all) of the insulating effect.

How Merpeople could best protect themselves in cold water is an interesting puzzle. Anyone got ideas?

Edited by DeMarquis on May 14th 2023 at 2:16:19 PM

It seems to me that there's also the potential issue that waterlogged clothing may become heavy, and a hindrance to movement.

That said, if the clothing could be made largely watertight—enough to significantly restrict waterflow, if not prevent it entirely—then I imagine that it might still serve as insulation: just as with air, the layer of water in contact with the skin would be warmed by body-heat. And if the water can't flow away and be replaced by new, still-cold water, might serve to insulate.

(If Wikipedia is to be believed, at least some type of wetsuit exists that employs a layer of warmed water rather than air.)

That said again, it occurs to me that if water-temperature is an issue for these merfolk, then what do to they do in situations that would make clothing problematic? Do they never take off their clothes...?

[edit] A thought: Might these merfolk circumvent (so to speak :P) the issue by living near relatively-shallow geothermal locations, which I imagine would somewhat heat the surrounding water...?

Edited by ArsThaumaturgis on May 14th 2023 at 10:26:48 AM

I suppose a layer of treated blubber might serve in place of a wetsuit. But living long term in cold conditions is still a challenge unless they have some sort of underwater heat source. There might be a way to design a furnace that works underwater, if you could connect it to above surface air and smoke venting pipes. Or maybe place the furnace on a floating platform, and pipe the heat underwater?

This is unrealated to the current issue but since Underwater Kiss requires Super Not-Drowning Skills which marine mammals do not have, would mermaids still evolve to find kissing romantic? Also how would mermaids communicate underwater?

I mean, could they not simply prefer shorter kisses...?

[edit] In any case, marine mammals can generally hold their breath for a very long time, as I recall—I think that they have "super not-drowning skills", at least as called for in most kissing.

Edited by ArsThaumaturgis on May 14th 2023 at 11:33:51 AM

Thanks I misunderstood the trope description and thought that kissing itself required you to breathe as in like you couldn't hold your breath while kissing. Now about the communication I was thinking about them having advanced humming, but I wasn't aware of how muffled sound would be underwater and how loud they'd have to be to communicate underwater.

Edited by Wild-Starfish on May 14th 2023 at 9:37:03 AM

Hmm... Well, I have two thoughts:

First, they could potentially use sign-language, which naturally doesn't rely on sound-propagation.

Now, sight does tend to be somewhat-restricted underwater—but at the ranges at which sign-language tends to be useful I'd expect this to not usually be a huge problem.

And second, if they have the means of producing and detecting ultrasound (perhaps by developing specialised organs), then that might work, I would think.

(Although I don't know offhand whether that is feasible in a human-sized creature; more research—or input!—might be required there!)

Of course, this presumes that they don't have access to even-more-specialised means, like producing light.