Mermaids (Mammals)

Mammalian mermaids have no relation to the species of fish nor to humans. They were discovered well after the species of fish was and were given the same common name due to their slight visual resemblance to their appearance (similar to how in the real world, American robins are named after European robins despite having very little in common). Their morphological similarities to humans are the result of convergent evolution.

Habitat:
This species of mermaid is a marine mammal native to that world's equivalent of the Arctic Circle. They have a similar niche to arctic seals in that they spend most of their time in the water but part of their time on land and their primary food is fish. Mermaids are obligate carnivores, and this type eats only fish and shellfish. Like seals, they absolutely rely on sea ice to reproduce.

Evolutionary History:
Despite their many similarities to seals, it is actually not known if mammalian mermaids' closest common ancestor is shared with seals or whales, because Curi never decided.

Physiology:
From the point where a normal aquatic mammal would have flippers down, mammalian mermaids have a completely ordinary anatomy for an aquatic mammal adapted for freezing water. Specifically, their anatomy is similar to a seal, but that could be the result of convergent evolution. Their tails end in flukes like a whale's rather than flippers like a seal. However, where a seal would have anterior flippers, mammalian mermaids have evolved arms similar in proportion to humans' arms, and ending in hands also similar to human hands (but with longer fingerbones so that they tend to remind people of a rodent's forepaws). They also evolved heads on an articulated neck similar to a human's, though shorter, which helps them look out for predators while on land. Underwater, they tuck their heads against their shoulders to be more streamlined while they swim.

Mammalian mermaids have excellent vision and hearing, both out of and underwater. They have a proportionally larger brain than other aquatic mammals, likely originally adapted to help them process sensory cues. This larger brain allowed them to evolve a human-like intelligence, and the structure of their necks and of their mouths allows them to speak the languages of humans (although their natural communication takes the form of squeaks, barks, and noises that sound like humans coughing). Despite the humanoid shape of their heads, they do not have outer ears or hair. They do have fur covering their entire bodies, and like arctic seals it is off-white when they are juveniles and darkens when they mature. A mature mammalian mermaid is primarily grey in color, ranging from pale grey to medium gray. They have black spots that look like freckles over the entirety of their bodies, and black marks on the inner corners of their eyes that look like tear tracks. Their eyes are significantly higher on their heads than a human's eyes, and are able to rotate farther in all directions than a human's eyes. Like all aquatic mammals adapted to freezing water, they have a thick layer of blubber for thermoregulation and ease of movement underwater.

Society:
Mammalian mermaids are social creatures that live together in small villages. Each dwelling in the villages contains a family group called a pod. Daily life centers around the pod, as each pod hunts separately from each other pod. For most of the year, most of the day is taken up by the pod diving into the water to hunt fish and shellfish. While swimming, they hold their arms against their sides and propel themselves forward with their powerful tails. To turn, they bend an arm at the elbow and use their forearm as a rudder.

After collecting food, they return to their villages and add what they caught to the communal food supply. The rest of the day is spent socializing. The adults in the village teach the children their lessons, and when they aren't in lessons the children play together. Mermaids don't have formal meals or predetermined meal times like humans do, but rather take freely from the communal food supply whenever they are hungry. Mermaids who for whatever reason can't leave their homes have food periodically brought to them by podmates.

At the end of each day, any food that had not been eaten is divided into two categories. A small amount is dried and kept in the village in case there is a day where not enough fish are caught. The rest is traded with the humans for the few supplies humans make that mammalian mermaids have use for. These are primarily medical supplies and materials to make fishing nets. Although they can catch fish without a net, it is a much more efficient way to fish.

Mammalian mermaids are literate and have their own written languages in addition to their spoken languages. (Because mating regions are so large, villages tend to communicate almost exclusively with other villages that belong to the same mating region, and as a result each mating region and its associated villages have a distinct language. Each village has its own dialect, but dialectic variations are subtle so that villages that are next to each other have nearly imperceptible dialectic differences. On the other hand mermaids from villages at opposite ends of a region may have some slight difficulty understanding each other.) Their traders and doctors also learn the written languages of humans. However, as a race they seem largely uninterested in books and written stories. They much prefer socializing to reading and aren't particularly interested in the kinds of stories humans write. Their own writing system is used solely for communication, mostly between villages. Mammalian mermaids who have a job other than just hunting typically work during the "socialization" part of the day, out in the open where they can chat while they work. The exceptions to this are those whose jobs require them to be available at all hours of the day (such as doctors) and those who work with humans - these are exempt from hunting and the latter only work during the "hunting" part of the day.

At night, pods sleep in cuddlepiles in their homes. Their homes resemble igloos, but maintain a temperature comfortable to them which is very cold by human standards. Throughout the year, mammalian mermaids celebrate several festivals. They are not capable of comprehending religion, and their festivals are entirely temporal in nature. They have festivals to celebrate the beginning of a new year, the beginning and end of the Days of Endless Sun (the part of the year where the sun never sets that far north), temporal markers in the migration patterns of their prey, the beginning of their mating season, and the end of their breeding season.

Reproduction:
The annual mammalian mermaid mating season is preceded by a festival held in each village, followed by a period in which all merfolk of reproductive age who do not have fully dependent children leave their villages to migrate to a single point in their region. Mating regions for this species are huge; the smallest "arctic" continent on that world constitutes a single mating region. The location chosen for mating is always out by the water so that the merfolk there can fish. On the journeys to and from that location they don't eat. Instead they rely on fat reserves built up by feasting during the festival and restocked during and after mating season proper.

Mating season proper lasts about two weeks. During this time, merfolk will mate with any merfolk from other villages (who they aren't related to) that they find attractive. Attractiveness is judged primarily by how much blubber they have (fatter merfolk are considered more desirable) and the appearance of their fur. Matings do not occur exclusively between merfolk that could feasibly conceive offspring (they have no concept of gender so the term "same gender mating" is meaningless in this context), and each merfolk will mate with several others over the course of a given season. Merfolk do not have "social" mates or a concept of couples or indeed of romantic attachment. Pods consist of gestational parents and their offspring, containing as many generations as are currently alive at any given time. After mating season ends, they spend three days hunting and feasting to replenish their fat reserves for the journey home.

Mermaids cannot hunt for themselves just before giving birth or while nursing their babies, so they live off the surplus food in the communal food supply. Baby mermaids nurse for about a year, and even after being weaned remain fully dependent on the parent that birthed them for three months. Therefore, mermaids capable of giving birth only mate every other year. Mermaids take about fifteen years to sexually mature, and remain reproductively viable for about twenty years. Mermaids past that age are responsible for maintaining the villages and keeping an eye on the children who are no longer fully dependent but not yet fully independent during mating season.