While all merpeople are different, they all share the same basic traits.
When mermaids come into contact with water for ten seconds, they grow long copper colored tails and a matching top. Their tails are covered in scales and end in a classic dolphin-shaped fluke. They also have a short dorsal fin running along the backs of their tails from their waists to a little more than halfway down the tail.
When mermen come into contact with water for ten seconds, they grow long light blue colored tails. Their tails are covered in scales and end in a fluke that, unlike a mermaid's, doesn't look like a dolphin's. They also have a short dorsal fin running along the backs of their tails from their waists to a little more than halfway down the tail.
They also lose their clothes they were wearing in human form which reappear when they become human again. There is a possibility that they could absorb their clothing into themselves as a side effect of their metamorphosis into mermaids. Their hair keeps it's natural color and length, but any hairties, headbands, hairclips or hairspray disappears, along with their clothes. When they dry, their hair will return to whatever hairdo it was in. Born mermaids turn naked when they first come out of water because they had no clothes to begin with.
It allows him to move water without touching it as well as expand it and mold it into different shapes. With this power a mermaid/merman can create balls of water, blasts of water or even geysers strong enough to lift people off the ground.
Cryokinesis is the power currently possessed by Lyla, and Sirena with the use of a Moon Ring.
It is the power to create ice as well as create and control blizzards and snowfalls. This is an upgraded version of Hydro-Cryokinesis.
Hydro-Thermokinesis is the power currently possessed by Sirena, Zac, Lyla, and Nixie
It allows a merperson to heat and boil water. This can be used to create steam, super heat objects or raise bodily temperature. This is the most dangerous power of the three because, control can easily be lost and it can create so much heat and dryness that it can even easily dehydrate people or even create fires. There is a disadvantage to this power because although water can be heated, the mermaid with this power has no control over its movement. This power can come in handy when in need of a steam cover, melting ice, or drying off quickly.
Gelidkinesis is the power possessed by Bella Hartley, and most likely Eva.
It allows a merperson to change the viscosity or thickness of water. Gelidkinesis has been shown to be able to turn water into a jelly-like substance. After a short time however this power has been shown to wear off as the water reverts back to it's liquid state. There is a disadvantage to this power: it makes water or drinks undrinkable.
Substanciakinesis is the power possessed by Bella Hartley, and most likely Eva.
Is the power to turn water into a solid state, without freezing it. It can be seen as an enhancement of Gelidkinesis in that it solidifies water instead of merely jellying it.
Mecokinesis is the power possessed by Bella Hartley, and most likely Eva.
It is the ability of combined substanciakinesis and gelidkinesis will equal the ability to explode water or jelly, and also be used to glue objects together or create enough sticky or jelly ease in objects causing them to poor bucket loads of goose or sticky slime.This has been used to manipulate and mold mud or slime.
Aerokinesis is the power possessed by Cleo Sertori, temporarily by Charlotte Watsford, and possibly by Julia Watsford.
It is the power to create and control wind and air currents. This is an upgraded version of Hydrokinesis.
Telekinesis is the power currently possessed by Zac, Lyla, Sirena, and Nixie
It is the ability to move objects and people with the mind, often in ways not visible to the naked eye.
Invisibility is the power possessed by Zac, Sirena, Nixie, Lyla.
This power was introduced in Mako Mermaids, as it was not in H2o:Just Add Water. It is used primarily by placing a hand near their head and possibly clenching it into a fist, releasing it to become visible again. This ability also allows the user to conceal other people and things they are in contact with.
Siren Singing is a natural merperson ability.
It was originally used by Cleo Sertori under the influence of the Full Moon, preventing her from becoming a mermaid. Sirena was asked to use this ability by singing the Enchantment Song, which preseumably guves the Siren Singing power to whoever sings it, and is not a natural power. Mermen are presumed to have this ability as well, as the computer Zac was researching mermen on said that mermen have enchanting voices, like their female mermaid counterparts.
Speed Swimming and the Tower of Light are also natural abilities.
Natuaral Merpeople Abilities
All merpeople have several common abilities. They all have a transforming power, in which they have absolutely no influence, 10 seconds after they come in contact with water. If all water is removed (dried) from the merpeople body before the 10 seconds are up then the merpeople will remain in human form. But if not dried, then the merpeople will grow tails. Every merpeople has a power over water.
Merpeople can stay submerged for long periods of time but they still need to breath air. Merpeople can hold their breath for at least 12 hours before needing to resurface but with more practice merpeople can stay under for much longer.
It is possible that the place where the merpeople transformation happened affects the powers over water, e.g. the Moon Pool at Mako Island gave the people the power to control, freeze and boil water, but the pool in the sea caves in Ireland where Bella changed gave her the power to turn water into a jelly-like substance and turn water hard.In water, merpeople also have the additional ability of speed-swimming. When merpeople speed-swims their body is enveloped in bubbles that they use as a jet stream to swim quickly with. This can be a great advantage when trying to run away from enemies such as another mermaid/merman or boats and other water crafts. The merpeople tails are also very strong, this is shown when Emma saves Zane by smashing in the steal door on Miss Chathams Boat.