My travels, documentation, and theories of the world

You've happened upon a tiny cecaelia! The quiet beige creature suddenly comes alive with pulsing blue eyes on a sea of glittering gold. It seem you've startled her! Best back away so she has a chance to calm down before you approach. You wouldn't want her to bite.

Cecaeliae are sentient mollusks, unrelated to mermaids, which are fish. Instead of being descended from them, cacaelia mimic the mermaid body plan, using their color-shifting chromatophors to form a pseudoface on what is actually the creature's main body. The mouth, nose, and eyes are all carefully controlled markings, while the eyes are set on the side of the head.

This Blue Ringed Octopus cacaelia has the same body plan as other octopus and cuttlefish "mermaids." Those cute shiny "cheeks" are actually her complex eyes, and the "eyes" on her face mere mimicry. Hopefully it works to warn you off of a surprise hug! That could end very badly for one of you. You see, those beautiful blue rings warn of a deadly tetrodotoxin venom she possesses, but would really rather not use. Why don't you get to know her first?

The Hadal Snailfish mermaid is one of the deepest mermaids ever recorded. The cold, high pressure waters allow her to keep her adorable shape as she hunts for tiny sea bugs in the muck of the darkest part of the ocean.

This is one of the many mermaid species humans have never seen in person. Instead, information and illustrations are ferried to the surface by vertical migrant mermaids. Scholars, mermosologists, and diplomats bring communication through the different zones of the ocean. But those who travel the furthest vertically must know the most languages.

Humans who wish to learn mermaid languages will usually stop at Pelagic, since most mermaids they encounter will be surface-dwellers. They may be able to parse Mesopelagic as well, as it is closely related. But as one travels deeper, the languages of the oceans change and twist until they are formed of sounds a human can barely comprehend, much less speak.

Mermaid beauty standards vary from species to species, some populations focus on color, others on form, fins, or function.

The Flowerhead Cichlids are a society that selected for large lumpy foreheads and contrasting colors. These individuals chase forms that seem so strange to us, but are irresistible to their fellow Flowerheads.

In addition to this feature, some will enhance their natural markings with ink injected into their scales. This one wraps her arms with pictures of snails, fish, and sharks.

Frilled Shark mermaid, celebrating the depths. These creatures have strange clusters of tri-pointed teeth, perfect for snagging the soft bodies of squid and drawing them in for the kill.

Many fish species make excellent pets, given proper enrichment and attention to water parameters. Acquire a sounding vessel from your local alchemist to see if there are any demons or angels haunting your water. You can add demons to angelic water to balance it back out and vise versa. Each species has an ideal water alignment, and after letting the entities fight it out and settle, you can safely add inhabitants to your pond or tank. I recommend a small school of neon tetras, with plenty of plants in which they can hide. You will enjoy watching this species school around, as they do quite well in captivity with the proper care.

There is no proper care for mermaids.

There is no proper tank size, or water parameters, or enrichment or plants or anything.

Mermaids cannot be kept as pets. But some people do keep them confined, and traded like livestock. This, of course, is slavery. Just as we are descended from apes and mermaids are descended from fish; we are both still people.

Of course there are those who disagree with this categorization; and there are those who do believe, but do not care.

The black market is a lucrative and deadly operation, crawling in the underbelly of most major human cities. They trade in mundane humans on occasion, but usually it is creatures and artifacts with some magical component: mermaids, fairies, even magic-touched humans such as werewolves, selkies, and ogres. The latter being very difficult to contain as a live specimen, so often their pelts are sold instead. These are marketed alongside unicorn horns, kelpie manes, basilisk fangs, and all else forbidden from trade by anyone with a heart.

Apologies.

These topics often distract me from the professionalism of my calling. Suffice it to say, if this series has inspired you to fantasize about pet mermaids, do not. Consider a mundane fish, and seek friendship with mermaids at your local outreach dock.

Mermaids rescued from market and the homes of decadent aristocrats have a long journey of healing ahead of them. Many cannot speak their own species' language, but pick up the language of their captors with ease. For this reason, rehabilitation is a joint effort between humans and mermaids, before returning them fully to seas and waterways.

Success is difficult, but rewarding. Much moreso than any value they could possibly have as "pets." Please be careful, and respectful of your fellow sentient creature.

There are many creatures in this world that earn the definition of "people." Their paths to sentience are as diverse as the shapes and sizes in which they come. For mermaids, mimicking humans and hunting them in packs led to intelligence, language, and society.

Mollusks never hunted humans. They stayed in the depths and communed amongst themselves and eventually with the mermaids who shared their habitat. Long before humans knew of their existence, mollusk and cephalopod people were part of many bustling mermaid societies.

Small wonder, then, that humans referred to as mermaids on every occasion in which we encountered them. As far as sailors knew, things that swim are fish, and thus octopus are fish, and thus octopus people are mermaids.

In truth, mermaids evolved from fully formed fish, which had long split off from the ancestor of mollusks. The other phylum was forging a new path without bones. Thus, sentient creatures who arose from mollusks could not be mermaids any more than they could be fish.

But the name has stuck around. "Octopus mermaid" is more easily parsed than "Octopus person," despite the scientific community's insistence on the latter. Those that make a distinction have coined the term Cecaelia for them, but this has yet to catch on. Beneath the waves, mermaids refer to them by a variety of names, depending on the language. In sea common, the term they use directly translates to "Mirror."

This arose because cephalopods have skin made of chromatophores; cells that flex to reveal and hide their color. These "mermaids" use this trick to create a pseudo face on the top of their mantle, with which they interface with actual fish-mermaids. Their real eyes are held on either side of their head, in the place where our ears would be. To further the illusion, the arms branch and split in a simulacrum of mermaid form: head accessories, two arms, a chest, waist, and tail. So creatures that evolved to mimic humans were in turn imitated, though for different reasons.

There are none more talented at disguise than the mirror known as the Mimic Octopus. This creature is able to stretch its form and change its colors to look like a variety of animals to hide, intimidate, or entertain.

This specimen is seen conversing with a lionfish mermaid on a peaceful coral reef. At first, the colors and shape shift only gently, as the mimic is relaxed in its natural form. Suddenly, it stretches out its spiraled tentacles, the subtle stripes growing into thick bands to match the venomous spines of its lionfish companion.

The two of them continue their conversation, punctuated by the cecaelia's kaleidoscope of shifting skin. Perhaps this is how they laugh.

The royal dottyback is a bicolored fish, where the front half is deep purple and the back half is bright yellow. On the fish, there are no stray markings; the purple is purple and the yellow is yellow with no extra spots.

But Royal Dottyback mermaids, like all other mermaids, can have extra colors, patterns and even fins. It is not a one to one equivalence. All markings can vary per individual, with the greatest differences occurring on the upper half.

A kid came on my stream from the mermay tag on twitch, saw the word "requests" and immediately asked for Luffy One Piece.

Now, normally you have to buy a request, and you submit a fish, not a person. But it was so sudden and so far removed from my mermaids, that the funniest thing to do would be to draw it.

Mermaids come in all shapes, not all of them humanoid. Still, some traits persist and propagate more than others. Fins adapted into eyelashes, brows, lids, and hair; other structures molded and emphasized, all of these come and go to different species of mermaids. Markings, including facial markings, can come in many shades and styles, Including those that happen to resemble human makeup ideas.

Some have it more intense than others.

Phantom Angler

We already know what a female anglerfish looks like.

A distinguished sponsor has asked to see a male anglerfish, of one of those species that attaches to the female and then atrophies into nothingness in the name of love.

Often mistaken for the much more dangerous sea serpents, massive oarfish mermaids are peaceful but imposing mirror-skinned figures who hang vertically in the open ocean. Their red fins appear colorless and invisible in deeper water, as red light wavelengths cannot penetrate the depths at which they rest and feed.

Just like humans, mermaids come in a variety of body types, proportions, musculature, and fat distribution. In academia, documented mermaids of each species tends to match the appearance of their fish counterpart. But individuals can look like anything.

This oarfish mermaid is a gorgeous example of the principle. The humanoid torso and the start of the fish body have rolls of fatty tissue, but it diminishes as the long tail stretches downward. Inside the torso, the swim bladders will be flexed to account for the extra buoyancy.

Mundane oarfish use their flat bodies reflect the sea around them like a smooth mirror. In order to be seen by other oarfish, they hold their long pelvic fins horizontally out to their sides, forming a cross with their body.

While this individual's shape is less useful for camouflage, the behavior remains. Many modern mermaids use community to fill their needs, and wits to avoid predators. So while different body types can affect hunting fitness, it does not diminishes their functioning within society.

The Longspine Porcupinefish isn't the only pufferfish in the sea.

The Guineafowl Pufferfish tends to come in two color morphs: dark with light spots, and gold. This individual is a rare third morph: a combination of the two colors in a single person. Combined with the lovely frilled fins and warm personality, this mermaid is the winner of much undersea fame.