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Your ancestor lost his mind, obsessed. He and his shipmen slaughtered these beautiful creatures in cold blood. Genocide — That's your legacy.
Helen Hawkins to Ben Pownall

Merfolk (or Merpeople) are an aquatic race of half-human, half-fish predators who have existed for hundreds of years in secret under the depths of the oceans of the world, including Bristol Cove, Washington.



Bristol Cove was once home to mermaids. Thousands of years ago, ancient human tribes and merfolk tribes were at peace with each other and lived together in harmony, as depicted by the cave paintings in a cave near Bristol Cove. Then over a hundred and fifty years ago, a Siren enchanted the men of Bristol Cove and a Captain, Charles H. Pownall, heard her Siren Song. She emerged from the sea to greet him and he fell in love with her. The Siren and Charles H. Pownall had a daughter that was born in transition and appeared deformed. He took his daughter to the Haida, people who weren't afraid, and had them cure her of her deformity. The Siren left, going back to her home in the sea, believed that her daughter was killed, lost her senses, and never returned. The Captain was so bitter and heartbroken by her absence and infected by her song that he and his men sought vengeance on the mermaids and slaughtered most of them in cold blood. As the genocide occurred even mothers were forced to watch as their babies were killed right in front of them. The survivors then decreed that the land is no longer a good place for them and that humans and merfolk must never again come in contact with each other.

Season 1

Ryn and Donna were racing in the sea one night when Donna was captured by one of the fishermen and brought aboard the ship. She attacked Chris and began to sing her siren song. The military then arrived in helicopters and took her to their military base, where she was placed in a tank and experimented on. Scientists took a sample of her DNA and placed it into fully paralyzed rats which caused it to be cured and healed.

Donna escaped the military facility with Chris, and at Libbey Beach is where Ryn and Donna finally reunited and returned home to their colony.

Levi and Donna attacked Ben and the other fisherman board the ship in "Dead in the Water". They got hurt but escaped.

Donna, Katrina, and Levi came onshore to Bristol Cove. Donna wanted to bring Ryn back to the colony with them, and Katrina and Levi wanted to kill Ryn. Katrina and Ryn fought and Ryn usurped her position as Alpha leader of the colony. After Donna got shot by Xander, Ryn, Levi, and Katrina took her to Helen's home. Ryn then told Levi and Katrina to leave and never return. Unfortunately, Donna died the next morning from the infection in the wound, and her body was buried in a special cemetery commemorated for merfolk who died in human form in Bristol Cove and Helen's ancestors. Ryn, feeling saddened by Donna's death and guilty for ruining Ben and Maddie's relationship, left Bristol Cove for some time.

Season 2

Months afterward, Ryn returned and decided to stay in Bristol Cove, but then something happened out in the water driving away all the marine animals and forcing them out. She later investigated some beached whales with Ben and Maddie and found one of them alive. She then went out to explore where the source of the problem was and found a shipwreck. There, she discovered another mermaid, dead. Then, a sound wave came out and caused great pain to Ryn. After discovering that a ship working for the oil company was using sonar, Ben and Maddie help Ryn recover from the sound waves damage.

Later, Ben, Maddie, and Ryn find another mermaid, who seemingly died while transforming into her human form. Then they found Levi, who barely survived. Unbeknownst to them, Katrina, along with four other merfolk (three mermaids and one merman) returned and found shelter in Helen's house before they, along with Ryn and Levi, were moved to a log cabin out in the woods to avoid possible detection from the people of Bristol Cove. If they show any sign of dehydration, they go to a secret water tank where they can temporarily revert to their mermaid/merman forms. Over time, they slowly become more insinuated amongst the humans as they learn the cultural and social traits of humans; all except for Katrina who still harbors resentment towards humans and Ryn.

Things start going from bad to worse when Katrina tries to persuade the colony to return to the water with her and abandon Ryn. Viv and Cami (Donna's daughter) join Katrina, but Sarge, Levi, and Eliza choose to remain loyal to Ryn. After a brief confrontation, the two opposing sides call for a truce as they all decide to work together to reclaim their home. After a little while, the tank water becomes insufficient and Viv begins to undergo complications following her transformation. Katrina decides to lead them, along with Helen Hawkins, to a cave she had found when she went out alone earlier. There inside the cave, they find some cave paintings made by an ancient tribe that had once been allied with merfolk several millennia ago. After Ben finally executes the plan to stop Klesco Oil from drilling any further, the merfolk give their gratitude to their fellow human friends. But the plan comes with a price.

Ryn's merfolk successfully sabotage the drillship owned by Klesco Oil and Gas, causing the well to collapse while it is captured on the live broadcast at the gala. After Ryn and her merfolk cut off the drill with blowtorches, the snag wire which is hooked around the drill comes off and is about to slice into Eliza and Viv, but Sarge swims in between them and ends up getting his throat slit. The other merfolk then carry him back to their home where he is given a burial. Moments afterward, Ryn goes around looking for other members of her colony, but unfortunately, many others had died, and she manages to find only three members still alive. After that, Katrina and Cami go out hunting where they find a plane wreck and find an elderly mermaid inside.

When mating season begins, both the mermaid and merman glow with an inner red light. However, young have not been born in many years, due to the humans throwing pollutants in the oceans.

Due to Ian Sutton's interfere and constant digging, their allegedly mythical existence has finally been exposed to all of townsfolk of Bristol Cove in "New World Order", resulting in an all-out war for the survival of merpeople, humans and hybrids alike. However, it turns out that it was all a premonition.

Season 3

In "Borders", a new antagonist arrives at the shores of Bristol Cove. She disguises herself as a flight attendant on a private flight that departs from Russia to Washington state. While in the air she kills the crew with an ice pick and sets the autopilot to plummet into the Pacific Ocean with the passengers still inside. She opens the plane's door and jumps out into the air deploying her parachute and landing in the water she removes her disguise as she transforms into her mermaid form, she swims her way to Bristol Cove.

Upon arriving, she gains access into the military research facility by stealing another's ID keycard, she wanders through finding everything about the experiments and tests conducted. She then goes to Helen's Antiquities where she finds Ryn, she immediately identifies that she is from another mermaid tribe. Tia explains that she was held captive by the Russian government for the past 10 years, and during that time they called her Vodnyy Zver which means "sea monster". Now that she is free, she takes up the name "Tia" after the vengeful sea goddess Tiamat a creator of oceans. She further explains that her captors taught her to speak fluently in 7 languages, as well as teaching her everything about science, engineering, technology, human history, and how to fight. They wanted to turn her into a warrior. She was injured in the ocean after attempting to slay a monster called Ga'anda (It is nowhere to be found in any existing book on mythology) for taking the lives of many merfolk. She put up a good fight, but ultimately lost resulting in her banishment, she accepted her fate and managed on her own until a Russian research boat caught her. She was tortured, bent to her captor's will, and then she overheard an intelligence report about the U.S Military holding another mermaid and escaped.

Tia persuades Ryn to let go of the old ways, to unify all the merfolk if they want to survive. She goes for a walk with Ryn, where she tells Tia that she came onto land to look for her sister Donna. After Tia hears that it was humans that killed her, she breaks into a car and uses a screwdriver to start the ignition stating that humans have possessions while mermaids don't. While driving Tia explains that she was not being held captive, she chose to stay to learn how to become stronger. Ryn tells her that she willingly participated to help Ben who she insists he is a friend of their kind, even letting someone die to keep their existence a secret.

Later, Tia tells Ryn that classical music has been the greatest human achievement for almost 200 years, and says to her that destruction has been the only thing that has happened since then. She tells her point of view with how humans are ruining the oceans, and unlike them, their merfolk create balance and take what they need as the most evolved species who were put on the Earth to protect it. She also wants to share resources among the united tribes and restore the oceans rather than remaining in conflict, later at Helen's apartment Tia suggests to Ryn that the human who took Donna's corpse should suffer the consequences, Ben is against her and says no. Tia decides to take care of it herself by texting Commander David Kyle from Ben's phone to meet him at the docks where she ambushes him, stabs him, and drags his body down into the water.

In "Revelations" it is revealed that there are many merfolk tribes all over the oceans have been divided, never going to another's territory, Ryn is influenced to do something to help her kind so she will agree with Tia to travel far to unite the tribes. Tia admits to Ryn that she did kill David Kyle, and tells her that humans are not their friends. At the Marine Research Center, Tia reassures Ryn that she is trying to help her, she mentions how her captors lobotomized her removing her ability to sing the Siren song. Katrina enters the warehouse to tell Ryn that a plane crashed in their waters (the same one Tia crashed in "Borders") and that one of their own saw her come to land. Ryn tries to tell Tia that killing all humans will not help their tribes, Tia gives her a warning that she will kill her if she stands in her way before diving into the water. Ryn follows her out to sea where they fight but sustains a number of injuries, Tia is forced to retreat after Ryn's colony arrives.

In "Survivor", Tia finds her former mermaid clan and duels the current leader, she kills her and takes her place.

In "Life and Death", Tia gathers more merfolk to lead an impending attack on Bristol Cove. Meanwhile, Meredith, the surrogate mother of Ryn's baby, gives birth. Afterward, Ryn takes her to the water to keep her from getting dehydrated.

In "Mommy and Me", Ryn begins to explore the duties of motherhood on land. When asked why she returned so soon with her baby, Ryn explains that she wants to teach her daughter about life on land and sea as she grows up.

In "Northern Exposure", Ryn, Ben and Maddie visited Robb's tribe located in Nome, Alaska, whose leader is Yura, in order to convinced them to help them in their war against Tia.

In "Til Death Do Us Part",

In "A Voice in the Dark",

In "The Toll of the Sea",


Known Merfolk

Ryn's Tribe

Tia's Tribe

Yura's Tribe

Humans Who Have Encountered Merpeople

Physical Appearance

Merfolks possess a strange, alluring quality that many humans are drawn to which is present in both their human and aquatic forms. Warrior merfolks are typically seen carrying spears they use as weapons to attack and kill their enemies.

Merfolks have a noticeable sexual isomorphism in terms of their aquatic forms. While females and males share the same scaly upper bodies, fangs, claws, webbed hands, webbed underarms, a pair of small fins right above the caudal fin, and dolphin/whale-shaped caudal fins, their tails and back fins are noticeably different in appearance.

Females have a large, single fish-like fin running down their human backs, three long sets of webbed fins running down their tails (one along the back, and two smaller ones each positioned on the side of the tail), and a stinger growing out between the caudal fins.

Males, on the other hand, have slightly longer tails, larger caudal fins, three or four pairs of fins shaped like those of dolphins, whales, or sharks running down their back, with an additional one positioned in the middle of the buttocks where the crack would be. Their tails also have dolphin/whale/shark-like fins along their tails in three pairs. One pair sticking out behind the thighs, one pair sticking out around the knee area, and of course a pair above the caudal fins similar to the females. Males caudal fins lack the stinger that mermaids have.

Different tribes of merfolks located all over the Earth's oceans also seem to have differentiated aquatic forms. The merfolk‘s aquatic form seem to be specifically designed depending on their environment thus separating one colony from another.

Eye color also helps to determine which tribe does a certain individual belong to (sometimes by origin) and (possibly) who is related to that individual. For example, all of Ryn's colony members have blue eyes, except for Katrina, who has purple eyes and is a part of Tia's colony as Tia too has purple eyes. Robb is from a different tribe, who has white eyes

A new trait that merfolk have is their ability to change their aquatic appearance. This phenomenon happens only when merfolks decide to join a tribe. When Katrina decides to go back in Tia's tribe, she changes her aquatic form and her fins become wider and more flexible. Her frontal portion turns light grey and she gains reddish-orange scales.


Merfolk usually only kill for survival. According to Helen Hawkins, Merfolk are highly intelligent creatures, more so than humans at least. This is displayed in Ryn's extremely quick grasp of the English language and her memory also appears to be quite superb. Merfolk have some difficulty adjusting to life on land; though given their in-exposure to human culture, this can be expected.

Because Merfolk have some difficulty speaking human languages, they tend not to speak much as they namely commune with high-pitched calls and wails. It can be assumed that they do have some kind of non-human language that they use in the ocean, as several of the merfolk have made references to stories they were told as children in the water about certain subjects. This is further confirmed when Tia communicates with her Tribe when it translated their language in subtitles. As babies, they don't cry right after they're born because crying attracts predators.

In "Mommy and Me", Ben mentions that many marine mammals trigger a hormone that affects their offspring's growth and adaptation, that is the case when an offspring is being cared for by the mermen as they have a different hormonal response than the females.

In "Northern Exposure", Yura's tribe located in Nome, Alaska has social skills that contrast with Ryn's colony: they are isolationists, staying in their waters and never leaving for any reason. The only contact they have on the surface of their waters are the human locals who they trade with under certain circumstances.


Merfolk live in groups of colonies in various parts throughout the Earth's five oceans. These colonies are led by matriarchal leaders, according to Helen. The leader of a colony is known as the Alpha leader.

Katrina is the former Alpha leader of a colony; Ryn later replaced her as Alpha after defeating her in combat.

Ryn reveals that in other parts of the ocean, there are other colonies who are more territorial and will do whatever it takes to protect their water. In fact, due to the vast oceans and the many wars fought by the different tribes, each tribe establishes its own territory in different parts of the world, including tropical and polar waters, in order to keep the peace. No two territories come in contact with each other, because it would incite territorial disputes. All mer-people sleep in caves, and they regurgitate their food to feed their offspring.

The episode "Northern Exposure" introduces a new tribe that isolates itself up north, in a remote shore off the coast of Nome, Alaska. They are lead by Yura, they fight only within their own territory on their own terms, never helping another tribe in their fight. The way the mermaids of the tribe enter and exit their waters is through an ice fishing hut, the visitor must give an offering (specifically rainbow trout) and they emerge from their waters soon afterwards.

The way the Merfolk measure how much time passes is by tides, and the migration of larger marine mammals. This is yet to be clarified further with comparison to how humans tell time.

Abilities and Attributes

  • Merfolk Physiology: Merfolk have a human-like upper body and the lower body of a scaly fish's tail instead of legs. While mermaids have the upper body of a beautiful female human with flowing long hair that covers their backs, mermen have the upper body of a handsome, muscular human male. Merfolk have blue eyes that comes in varying shades. Both mermaids and mermen have dagger-like teeth and talons used for catching and tearing prey. They also have gill slits on their rib cage that enables them to breathe underwater and syntactically, digits fused together forming webbed hands, which reduce water resistance when they swim. In addition, they have a vertical tail fluke, similar to a cetacean's, used for propulsion. A barbed stinger at the end of their tail that is very sharp and piercing and is used as a weapon or for self-defense, though only the females have them. Both sexes have grey skin that is covered with silvery-grey scales of varying hues, including the human half. Their voice boxes are a hybrid of a larynx and a syrinx at the base of their trachea. Mermen are seen with spikes on their backs.
  • Scale Manifestation: Their scaly fishtails are silvery gray and have pelvic fins on either side of their tail, which assist them as they move vertically or turn sharply in the water. A large dorsal fin runs down their backs while a much smaller one runs down the backs of their tails.
  • Speed Swimming: Naturally, they are capable of swimming at great speeds in the water.
  • Enhanced Senses: Just like sea lions, whales and dolphins, they can hear sounds far off the ultrasonic frequency, giving them splitting headaches. For example, the strong hypersonic waves emitted by the oil rig has even caused death for some. They have enhanced night vision.
  • Fang Retraction and Enhanced Bite: In their true aquatic form, razor-sharp fangs appear in their mouth, with which they break steel in one bite.
  • Human Disguise: After surviving a painful metamorphosis during which their tail changes into a leg and their skin changes color, merfolk are able to take their place among humans. Sometimes, the transformation does not even occur immediately, and merfolk can be able to retain their aquatic forms on land. This could be because those areas are still wet from the seawater splashing onto the surfaces.
  • Water Maneuverability: As well as swimming at high speeds, they are capable of maneuvering freely underwater.
  • Extraordinary Physical Strength: Merfolk are noticeably physically much stronger than humans. Ryn was able to overpower a large adult male and threw a pipe with enough force for it to pierce a wall. She was also able to lift an anchor and throw it without difficulty. Also, Katrina was able to punch through the glass window without experiencing any recoiling pain when she attacked Dale. This is due at least in part by the fact that the bones and tissues of a mermaid are incredibly dense; the very petite Ryn, who is roughly 5'4" tall, was shown to weigh at 196.6 pounds despite having a thin, lean build. This enhanced density also makes merfolk extraordinarily durable and resistant to harm. It also allows them to swim in deeper depths without worrying about the ocean's pressure.
  • Enhanced Regeneration: Merfolk possess greater regenerative capabilities than humans. They heal quickly from non-fatal injuries within a short period. This gives them a very strong tolerance to the effects of alcohol, with both Ryn and Levi being shown drinking beer, wine, and liquor without showing much outward signs of intoxication.
  • Siren Song/Hypnotic Singing: Mermaids possess a strange, alluring quality that many humans are drawn to which is present in both their human and aquatic forms. They can use their voices to sing a wordless song that can manipulate a human's feelings or actions, depending on its intentions; this can range from influencing a person to defend the mermaid from others, attracting a human to them, or compelling them to stop an action (such as trying to shoot them with a tranquilizer gun, for example). This song has a negative effect on humans, creating a type of lesion on the brain beginning in the frontal lobe, the region that controls impulses and inhibitions, which can lead to side effects ranging from hallucinations, delusions, lowered inhibitions (preventing someone from doing something they want to do but know they shouldn't), and even causing some to do things they do not want to do. Some mermaids (typically healers) can also learn to use their voices to sing a sequence of tones which, when accompanied by hand gestures over a person's body, is capable of moving pain out of it.
    • According to Levi, only mermaids are capable of this power, as mermen are not able to sing. Ryn also explained that merfolk are only capable of singing the siren song when they are in the presence of a human, as when she was asked to sing into a recording device whilst Maddie and Ben waited outside, Ryn responded, "Song only comes when I sing to a human." The use of a mermaid's singing voice to remove someone's pain is described by Ryn as not being a true singing like their siren song, but more like humming, which seems to be supported by the fact that Elaine Pownall has not experienced any negative side effects as a result of hearing Ryn's voice for this purpose, whereas Chris, Decker, Ben, and Maddie all suffered neurological side effects as a result of hearing the siren song (by Donna in the former two cases and Ryn in the latter two cases).
  • Bioluminescence: When mating season approaches, both males and females emit a glowing red light that draws them close to each other.
  • Reproductive System: A mermaid has a biocornuate uterus, a uterus with two conjoined cavities just like that of a whale's or dolphin's reproductive system. It is how they can carry their offspring during its development.
  • Egg Fertilization: In "Sacrifice", we see Ryn's eggs extracted from her and go through an IVF (in vitro fertilization) process and immediately upon being fertilize, they divided faster than a human's.
  • Quick Gestation: Unlike a Human fetus, Merbabies remain in their mother's wombs for less than 9 months.
  • Extremely Long Lifespans: It's unknown exactly how long a mermaid can live but they can live much longer than humans. As Sarge appears to be in his 60s, he is actually 200 years old. Tia is also 150 but appears to be younger than Sarge.
  • Physiological Transformation: It has been revealed that any mermaid/merman who joins another tribe will change their physiological structure to match the tribe's individuals. Katrina gained a lighter complexion on her front part, wider pelvic fins, and reddish-orange scales and fins on her arms and body. This has been seen only underwater.
  • Circulatory System: As we learned in "Interview With a Mermaid", a mermaid's heart beat faster than a human's, while on land their heart rate beats at the same rhythm as a human. When a mermaid isn't with their offspring, they can feel their heartbeats to know if they are in any danger or not.
  • Sex Transition: In Yura's territory outside of Nome, Alaska, a transition pool of ocean water allows for her mermaids to change into mermen to procreate. Yura transitions from female to male after Ben, Maddie, and Robb purify and restore the water to its healthy state.
  • High-frequency Scream: Younger mermaids learn the Siren Song from their mothers, before then their voices are very high-pitched. Hope's high pitched scream produces a frequency with energy that exceeds roughly 556 hertz, which causes the glass in Helen's shop to shatter.


  • Dehydration: Merfolk are unable to survive on land for extended periods of time. After prolonged deprivation of water, they will begin to asphyxiate, their eyes become green, and their skin will become extremely dry and irritated. After an extensive period of dehydration, their body will begin to shut down. Merfolk are able to spend more time on the surface each time they transform to occupy land.
  • Mortality: Since Merfolk are living creatures, they can be killed by conventional means (e.g. blood loss, decapitation, starvation, suffocation, and etc.). In fact, during their transformations into human form, the pain can be so great that some may even die while transforming.
  • Ocean Water: Whilst Ryn's colony were capable of temporarily surviving on land by transforming within a tank filled with ocean water, this eventually proves to be incapable to sustain them. According to the merfolk, the water must be alive for it to properly sustain them.
  • High Stress: As displayed by Ryn, following the extraction procedure for her stem cells, her cortisol levels spiked up moments afterward, causing her to become more aggressive and stressed until the point that her predatory instincts returned. Singing the siren song has been shown to help alleviate this side-effect.
  • Water Pollution: As told by Maddie, merfolk are prone to infertility in the water due to pollutants that humans had dumped into the ocean.
  • Loss of Aquatic Form: Merfolk who choose to frequently travel to and from land can lead to a serious risk. According to Robb he cannot transform into his merman form anymore. This is because prolonged abstinence (at least several years long) from seawater can make the transition into mermaid/merman form last longer and it is harder to endure its agonizing pain, with the latter potentially leading to death.


Their diet consists of seafood such as fish, shrimp, clams, crab, and lobsters. In "Pilot", a shark's head was seen with bite marks indicting Merfolk eat shark as well. Ryn also killed and ate a rat when she was first on land. Though Ryn and the other merfolk initially seemed repulsed by food that wasn't fish once they took human forms, they have been shown to soon develop a taste for other human food; Ryn has been eating a variety of fruit and side dishes and has professed her love for Jell-O, while Cami was seen enjoying grapes by tossing them into her mouth.

Merfolk have also been shown to enjoy alcoholic beverages while in their human forms, with Ryn often partaking in social drinking with her human friends and Levi making his fondness for beer very well known.



In the water, females and males aren’t equal; women are in the position of authority while men act as their subordinates. Due to the matriarchal society of the merfolk, it is usually the females who do most of the activities underwater such as hunting and are always seen eating first, when facing an enemy, both sexes participate. When mating season arrives, the male and female's skin glows red to draw potential mates in, but the females are the ones who choose with whom they mate. Despite this, the mermen do respect the females.

When a mermaid or merman dies, their family takes their body and swim for a long time, taking the body to the deep ocean and leaving it in a special place so no other animal can find it, similar to a funeral. Merfolk also have a belief in the afterlife, which they call the Spirit World. They can be able to make contact with the spirits of their deceased members that are said to continue to roam the waters and even on land as demonstrated by Sarge's spirit. The voices of the deceased are remembered by those Merfolk who are alive, once all the members of the colony are dead the voices disappear.

The males can attract potential mates by stretching and twisting their necks and produce a kind of bio-luminescence. Then the females bite on to their male mate's necks and smack them with their tails. Ryn later states that males can even die from excessive mating. Merfolk are able to have offspring of their own, but only in clean seawater until they learn how to mate on land. If a merbaby loses both its parents and/or gets separated from its natal colony, another colony can be able to adopt the merbaby and raise it as one of its own, as in the case with Katrina. When a merbaby is born, the mermen take it back to the colony so that they may teach it to hunt and survive in the ocean, not seeing their mother again until a mature age as explained by Ryn. During their time with the mermen the child learns to slay their first predator in the water, Hope uses her spear to slay a moray eel while accompanied by Levi and Mate. Once the child makes their first kill, that is when the mermen decide to return the child to the mother.

Whenever a mermaid/merman is left injured and has failed to establish victory over a fight or battle, the colony would abandon that individual, as described by Tia.

In Yura's Tribe, every mer-person is born female. They select the most eligible mermaid to go into the water of the transition pool to change their sex for procreation. Without it, the population would decrease.

When one successfully defeats or slays the leader of an existing tribe in a duel, that mer-person becomes the new leader. In "Street Fight" Ryn defeats Katrina in combat deposing her as the matriarch of the colony. Tia slays the current matriarch of her tribe in "Survivor" and becomes its leader. In the climax of "The Toll of the Sea", Ryn pierces Tia with two spears killing her. All the Merfolk of the tribes bow to her, implicating that she is the Alpha of all of them.


In "The Last Mermaid", Ben follows Commander David Kyle to discover a room filled with the bones of Helen's mermaid hybrid family robbed from their hallowed graves. The fossils contain traces of mermaid DNA that would reveal relatives of the family tree tracing far back years or decades into the past.


In "Entrapment", Katrina took Helen and Ryn's colony away from Bristol Cove to the forest, they arrive at a cavern with cave paintings left by an ancient tribe. The drawings depict an existence where humankind and Merfolk were once together, we can learn from these paintings that the Merfolk had peace with the human race on land with the following: "We live in peace and harmony, tribes of land and tribes of sea". The evolution and bio-social variation are underlying themes that deal with the merfolk's nutrition, child growth, health in societies, genetics, populations, and their adaptation to any surrounding environment.


Underwater, they can be able to use their arms and hands to communicate in a unique sign language, similar to that of the human variation. Contrast this with the way they learn to speak while on land: their English vocabulary (or any language) starts off with very few words, as they spend more time on land it can begin to expand up to the point where Ryn speaks in full sentences. So far, Tia and Robb speak English more sophisticated than all the Merfolk introduced so far. Hope, on the other hand, has been taught the Merfolk sign-language as she can understand when Ryn speaks to her.


Throughout the series, the Merfolk explore how life is like for humans on land as well as its environment:

  • Eliza and Viv learn from Helen how cosmetics bring a lot of attention to a women's appearance.
  • Levi learns about the leisure that humans enjoy such as social drinking, television, and dancing.
  • Ryn acquires human knowledge from books and encyclopedias, experiences air travel, learns about motherhood on land, and the use of currency.
  • Mate learns of the way humans mate on land.
  • Cami tries new forms of eating food, such as tossing them in her mouth.
  • Sarge using a hammer to board up the broken door window to Helen's shop.
  • Tia's quantity of intelligence she obtained during her time in captivity with the Russian government (Aside from Robb, she is the only mermaid to have the largest amount of knowledge).


Mermaids like Eliza practice medical knowledge and become healers for their colony. They learn to use their voices to sing the song that helps alleviate pain, and to create medicine using any plants and algae found in their oceanic environment. In "Survivor" Helen assists Eliza in making mermaid medicine using mussels, crustaceans, and various aquatic plants. Botany is also an important factor in the Merfolk's medical anthropology, this is demonstrated when Eliza and Helen explore the forests outside of Bristol Cove collecting herbs, they use these to create a strong concoction that allows Helen to visit the mer-people's Spirit World. Eliza treats Xander in "A Voice in the Dark" by putting small salt crystals in his right hand, and using her hands to heal the affected areas causing his heart rate to stabilize.

Social Psychology

The mer-people in Yura's tribe have a strong relationship with the human locals who reside in the same region as them. They gave them enough seafood to last during a harsh winter season, this is a clear example of reciprocity and a fact that a population of humans already knows of their existence.


Merfolk have remained a secret to the world for centuries, but as time passed many anthropogenic actions have reshaped the oceanic climate prompting them to resort to other methods for their survival. In the modern day era that the series takes place in, global warming, over-fishing, polluted waters and garbage gyres are already affecting the Earth's oceans, which is changing the Merfolk's livelihoods in permanent ways. But because of Robb's oceanic cleanup project, some of these environmental damages will soon be resolved.


Season 1

Season 2

Season 3