e621.net · 5552999

"Elvianian "regular" or "little" mermaids (Sirena vulgaris) are one of the species most closely related to the Golden Elves both from a phylogenetic and a social point of view.
The current view on mermaids evolution is that they diverged from their common ancestor with the Golden Elves and adapted to a marine environment rather recently, maybe even less than one million years ago. This is probably why it is still possible to find mermaid individuals showing abilities reminiscent of their terrestrial cousins, notably with regard to their digestive system.
Socially, as most of these mermaids settlements are found on the shores of the territories inhabited by the Golden Elves, the two species keep close links, performing trade and speaking closely related languages, individuals of one species being often fluent in the language of the other."

From : "On the origin of the Elve's species, by the way of a lot of weird biological shenanigans that never ceases to stupefy me"
by Pr. Syna Kirveen, Merula Press.