One of the most iconic mythical beings are mermaids. Mermaids have been regarded as beautiful creatures who tempted sailors and more recently became one of the most beloved characters in Disney. I am thinking of including mermaids in the second volume of my fantasy series, but they will be like nothing like the traditional version. I will be turning my attention to the evolution of both dolphins and humans and see how such a connection would be possible. There is a theory called the aquatic ape theory, which describes the possibility of an offshoot of humanity evolving to life in the ocean millions of years ago.
In terms of appearance, I can picture mermaids to resemble humanoid dolphins. They would be hairless because hair only creates drag underwater. Their skin would be leathery like a dolphin’s and be dark on their backs and light on their bellies in order to blend in with the deep sea like a great white shark. Their faces would seem human except their eyes would be larger for low light conditions and their brows would be thicker to accommodate the same organ dolphins and whales use for sonar. Their hands would be webbed to give additional thrust while swimming yet have enough dexterity to grip objects. In terms of diet, mermaids would feed on small fish, mollusks, cephalopods, and crustaceans. With locomotion, their legs and lower spine would fuse into their tails, but I imagine them resembling the shape of a wide paddle. Like other hominids in the past, mermaids would make tools and weapons from whatever they can find on the seafloor.
Overall, I am going to be scientific with mermaids in my fantasy series just as I was with dragons.