Random idea I had-

Water larynx live in both salt and freshwater. Salt water Larynx tend to be more colorful, whereas fresh water Larynx have a more brown and murky color scheme. Water larynx vary as well, some have fins, while some have legs and a tail. Instead of wings, water larynx have a fin on their back, Some can be born without a back fin as well. There used to be water larynx that lived in arctic waters, it's unclear what happened to them....