|“||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 specifically mermaids and mermen) are mythological sea creatures with the upper body of a human and the lower body of a scaly fishtail.
Bristol Cove was once home to mermaids. Over a hundred 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 doctors who weren't afraid and had them cure her of her deformity. The Siren left, going back to her home in the sea, and never returned. The Captain was so bitter and heartbroken that he and his men sought vengeance on the mermaids and slaughtered them.
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 a fully paralyzed rat which caused it to be cured and healed.
Donna escaped the military facility and Ryn and Donna finally returned home to the colony.
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.
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 which 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 syndactyly, digits fused together forming webbed hands, which reduce water resistance when they swim. Their scaly fishtails are silvery gray and has 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. 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. They both 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 tracheas.
Mermaids possess a strange, alluring quality that many humans are drawn to which is present in both their human and aquatic forms. Warrior merman are typically seen carrying spears they use as weapons to attack and kill their enemies.
Merfolk live in colonies in the sea. 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 (Siren, Alpha leader; currently)
- Donna (Siren) †
- Katrina (Alpha leader; formerly)
- Ryn and Donna's Mother †
- Unnamed Siren †
- Levi (warrior)
- Helen Hawkins (1/8)
- Amphibious Transformation: Merfolk are able to take on an ordinary human appearance through a painful metamorphosis to blend in with modern society and avoid being detected for varying lengths of time. Merfolk who gained legs and later went back into the water go through a painful transformation process. Their teeth become dagger-like and their skin turns into silvery-gray scales. Their hands become talons and a dorsal fin emerges from their backs. Their legs fuse together to form a scaly fishtail. Merfolk can only transform in ocean water, proven when Ryn was pushed into a swimming pool but remained in her human-like state. When they transform into their human-like forms, they shed their scaly fishtails.
- Aquatic Habitation: Merfolk can survive and adapt to underwater environments including enduring high water pressure and extreme water temperatures. They are able to survive the high water pressure of the deep ocean and can swim in colder waters.
- Speed Swimming: Merfolk are able to swim at extremely high rates of speed with minimal restrictions to water resistance.
- Extraordinary Physical Strength: Merfolk are noticeably 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.
- Siren Song: Sirens are exclusively able to emit a captivating and irresistible hypnotic singing voice that lures anyone who hears it toward the mermaid. Apparently those who are exposed to it have lingering side effects; the exact nature of these symptoms are as of yet not clearly defined. Ben compares it to a drug, describing it as something he needs. Eventually, the Siren Song leads the man that hears it to hallucinate seeing that mermaid everywhere and hearing their Siren Song out in the ocean. The victim will then be driven into the water to find that mermaid and eventually drown. Whether or not both genders of Merfolk possess this ability is not yet known.
- Enhanced Regeneration & Self-Healing: Merfolk possess greater regenerative capabilities than humans. They heal quickly from non-fatal injuries within a short period.
- Dehydration: Merfolk are unable to survive on land for extended periods of time. After prolonged deprivation of water, they will begin to asphyxiate, 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.).
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.
When Merfolk die, their family takes their body and swims for a long time to the deep ocean so no other animal can find it and leave it in a special place, like a funeral.
- Pilot (first appearances)
- The Lure
- Interview With a Mermaid
- On the Road
- Curse of the Starving Glass
- Dead in the Water
- Being Human
- Street Fight
- 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.
- Her memory also appears to be quite superb.
- Thus far, Merfolk have some difficulty adjusting to life on land; though given their inexposure to human culture, this can be expected.
- Because Merfolk have some difficulty speaking human languages, they tend not to speak much.
- Merfolk seem to not have birth given names.
- Merfolk usually only kill for survival.
- Merfolk can spend more time on the surface each time they transform to occupy land.
- The hybrid child of a Merfolk and a human will be born in transition and appear deformed.
- It is unknown if hybrid children of Merfolk and humans have the same powers, abilities, and weaknesses Merfolk do.
- It is currently unknown how Merfolk reproduce.
- It has been shown that Merfolk can reproduce with humans as the Siren had a daughter with Charles H. Pownall.