Seapony (Friendship is Magic)

Seaponies are a race of aquatic creatures with -like characteristics, distinct from Mermares, Sirens, and Kelpies.

History
Seaponies are known to inhabit the underwater domain of Aquastria, where they live alongside Mermares and other aquatic beings under the role of Merlion King Leo. A book, Sea-Ponies, was included in Princess Celestia's library, while a book on Seapony etiquette was among those in the Castle of Friendship library.

When the Hippogriffs fled Mount Aris, Queen Novo used the Pearl of Transformation to turn them into Seaponies so that they could live in Seaquestria. Later, when the Mane Six arrived in search of them, Novo used the pearl to transform them into Seaponies as well, though she later returned them to normal. Following the Storm King's defeat, all the former Hippogriffs were given necklaces containing fragments of the pearl, allowing them to change from Seapony to Hippogriff form at will. Many took advantage of this opportunity to return to Mount Aris, though some Hippogriffs remained in Seaquestria as Seaponies, and others continue to travel back and forth between the two.

Biology
Several varieties of Seapony are known to exist, with a number of different traits. Aquastrian Seaponies resemble giant, colorful seahorses, but with heads similar to those of land-dwelling Ponies and large, transparent side fins. Ponies who are transformed into Seaponies retain their normal forms, except that their back legs and tails merge into fishtails; those with wings gain wing-like fins in their place. Orcaponies are a variety of Seapony resembling a transformed Pony, including manes, but with the markings of an orca whale.

Transformed Hippogriffs are typically larger than transformed ponies, gaining Horse or Pony like snouts in place of their beaks, and with fin wings. Their front legs resemble those of transformed ponies, but with fin-like ends resembling hooves. Some of these possess growths like those of anglerfish on their heads.