Mermaids/Mermen:

When on land they appear as normal humans, but in water they sprout fish tails and gills! These mer-people are thought to be legends, but some belive they exist and go to great lengths to prove to the world that they are real. A mer who isn't careful though might get caught. A mer who is will use all of their many abilities to prevent themself from getting caught. Mer people have differnent abilities based on their gender (even though that sounds a bit sexist). 

-All female mers have beautiful singing voices that can lure men to the water, healing abilities that can be used by simply making contact with an injured person, control over water, and the ability to summon/ talk to sea creatures. They also have special fins on their forearms, similar to the fins of a lionfish, that release poison. 

-All male mers have sharp teeth like a shark, the ability to let out a high pitched shrieking sound that can stun any human, the ability to summon/talk to sea creatures, and control over water. 

Selkies:

This creature from mythology isn't very well known. In the sea they live as seals but they have the ability to go on to land and shed their skin to become humans. They normally will hide their seal skin and come back to it later when they want to return to the sea. They merely have to slip it back on, jump in the water, and they turn back into seals. If their seal skin is stolen, they become a slave to whomever it is who posesses their skin. When in their human forms they are very beautiful/handsome. They generally do not get along well with mermaids. 

Humans: 

Most of them are totally oblivious to the existance of the mythological creatures living among them, but a chosen few who are able to keep the secret do know. Either way they just live normal lives in the town. 

Hunters:

Dead set on catching the mythological creatures to sell for good money, they don't care what kind of creature they're catching, how the creature feels, or anything. All they care about is if the creature fetches a good price. They generally have their own boats stocked with fishing nets and other things they may need in order to capture a mer. 

Scientists:

Determined to catch a mer for the sake of science, they use all of the high tech equiptment such as hidden underwater cameras, hidden traps, hi-tech fishing boats, and other various tools. Were they to capture a mer, they have a special tank waiting in their outpost which is located right on the beach.