The Seaponies evolved from land dwelling earth ponies, unicorns and zebras, present on the Summer Sunset Isle's and other such landmasses during the balefire fallout. The survivors and their descendants began evolving to live on and off the limited land, eventually becoming the amphibious seaponies.
The seaponies developed their own culture and religion that replaced Princess Celestia and Princess Luna as their primary deities with Poseidon, the first Seapony. The Seaponies split off into smaller tribes living on the island chains, their capital being located on the bottom of the sea.
Species of Seapony
Seaponies primarily come in two varieties
The standard variety of seapony are found living close to the surface and are fully capable of living on and off land. These seaponies have forelegs similar to their ancestors that allow them to walk on land.
Regular Seapony - They are similar to standard earth ponies, except they have fish like tails instead of rear legs.
Seapony Zebra - Like their earth pony counterparts, only descended from zebras
Unicorn Seapony - These seaponies have forelegs and unicorn horns like their unicorn ancestors, allowing them to use magic.
This variety of Seapony are more fish than pony, lacking the forelegs of the rest of their species and have small fins on their sides instead. Deep ones can come in unicorn or standard seapony varieties.
Seapony Culture is tribal, each tribe maintaining their own traditions. They normally trade with one another or trusted individuals who have earned their trust. They typically avoid land dwelling pony species who may try to exploit them or view them as freaks. Seaponies revere Poseidon the god of the sea, rather than Celestia and Luna like their land dwelling cousins.
Reef Dwellers - A small tribe of seaponies and one of the farthest from their capital in Summer Sunset Isle.
Bottom Feeders - Mentioned by Riptide
Spotted Sharks - mentioned by Riptide