Siren

Sirens are a type of merpeople who are able to lure sailors towards rocky shores via their hypnotic singing, causing the sailors to crash into the rocky coast of their island, meeting a watery demise.

Origin
In Greek Mythology, the Sirens (Greek singular: Σειρήν Seirēn; Greek plural: Σειρῆνες Seirēnes) are dangerous predatory creatures who lured men using their enchanting voices to shipwreck on rocks.

Difference with Merpeople
The main difference between merpeople and Sirens is that the latter are predators and killers. Seducing men with their voices and bodies. Merpeople may not necessarily kill people, like Sirens do.

Merpeople are known as beautiful aquatic creatures that used their voices to enchant sailors and fall in love with them.

Dictionary
A mythical half-man half-mermaid/merman creature from ancient Greece that lived by the sea. Originally referred to as a god that singing voice had the power to disrupt the minds of those that listen to it. In fact this creature is the root word of the English word "Siren."

Powers and Abilities
Like the rest of the merpeople, Sirens have identical abilities and powers with the only exception being the inclusion of the Siren Song: Where this places the Siren species as a whole in the power-ranking of all monsters is unknown, but their sheer power and inherent potential likely place them as being high-class monsters, though it is unknown if they are included in the S-Class category, though it is possible that they exist at the boundary immediately beneath it.
 * 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 scales; silvery-gray scales for mermaids. 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. When they transform into their human-like forms, they shed their scaly fishtails.
 * Aquatic Habitation - Sirens can survive and adapt to underwater environments such as high water pressure and extreme water temperatures.
 * Speed Swimming - A Siren's powerful and streamlined tail and huge flukes can propel them through the roughest waters with incredible speed, grace and agility with minimal restrictions to water resistance. Like a dolphin, their fins can propel them high out of the water.
 * Extraordinary Strength - Sirens are naturally stronger than humans.
 * Siren Song - Sirens are able to emit a captivating singing voice that lures anyone who hears. it toward the singer. Apparently those who are exposed to it have lingering side effects; the exact nature of these symptoms are as of yet not clearly defined. Eventually, the Siren Song leads the person that hears it to hallucinate seeing that merperson everywhere and hearing their Siren Song out in the ocean. The person will then be driven into the water to find that merperson and eventually drown.
 * Regeneration - Sirens possess greater regenerative capabilities than those of humans. They heal quickly from non-fatal injuries within a short period.
 * Voice Amplification Form: This form serves the function of condensing and boosting the power of the Siren's sonic attacks, rendering them strong enough to readily cleave through solid matter such as concrete, rock, dirt, etc. as well as rendering their physiologically-degrading attributes quite likely immediately lethal to all but the strongest opponents. The potency of a sonic attack issued forth in this form has been likened to being as forceful as an explosion triggered in by a small electrical spark, showing the raw destructive potential of a sonic attack when fired in this form.
 * Sword Scale: This attack results in the tail scales becoming incredible stiff and hard, likely to the point of being as strong as steel. They also become razor-sharp, and are launched at high speed, swiftly piercing the flesh of their opponent and inflicting considerable injury. This ability likely exists as a back-up attack in the event of the traditional sonic attacks being neutralized or avoided.

Trivia

 * Sirens have circular markings on their tongues. These patterns may what give sirens the ability to use their voices as weapons.
 * When a Siren sings, a glow can be seen in the back of their throat (likely from the vocal cords).
 * A Siren is pretty much defenseless if they are susceptible to colds and laryngetis, which both affect the throat.
 * Its also likely that if a Siren burnt their tongue on spicy food, it would affect their singing.
 * When used offensively, the soundwaves of a Siren's voice appear as pulsating rings.
 * It is currently unknown if being a Siren is hereditary.