I always prefer realistic looks to the sirens, makes them majestic to live up to the legend and initial depiction in the show. Though I do believe the Dazzlings are juvenile in state of age since their species is immortal through the gemstones. In Siren’s Remorse they have a population and a set of rules to live by to continue keeping a source of negative emotion available, harvesting when needed and hiding away in their own little piece of paradise. They are not spirits in any sense, just specialized creatures who only the females can sing and attain dark magic through negative emotion feeding.
 
 
The males are geared out to handle the worst of the worst predators and poachers, armored and designed to fight and pulverize whatever the siren’s cannot subdue with their songs. Their dorsal crests or sails are hued in color both as a warning to would be predators as well as to attract a life mate. Pups or Hatchling sirens are guarded with the utmost ferocity as even though they are immortal, there are things out in the wild that sustain themselves off siren kind. New members are the security to the pods legacy and the health of the unit under the ruling matriarch.