Alright, so the pooka has a proper Gaeilge spelling (Púca) but what about selkie (selchie) and kelpie? I'd imagine something like selchí for the former, but wouldn't that be plural? Is the singular selcha? or am I barking up the wrong tree?

Well, a kelpie is a type of water horse - that would be "each uisce" in Irish. Alas, I have no idea how you would say "selkie" in Irish but I am dying to find out.

I'm not sure "selkie" has an Irish spelling. I think the word derives from Old Norse. I've never seen any word that would be the Irish version of selkie in Irish. If there is a word, I guess it has nothing to see with "selkie".

Tá scéal béaloidis maidir le bean a bhí ina rón agus ar fuair fear cumhacht uirthi tríd an seithe a chuir i bhfolach. Sin an saghas créatúr selkie, nach ea?

Maighdean Mhara (i. mermaid) atá sa bhéaloideas gaelach.

Tá an scannán maoithneach Inis Roan bunaithe ar an scéal úd!

Bhí píosa beag ar an Mooney Show are RTE Raidio 1 cúpla seachtain ó shin faoi Seahorse Ireland, agus an ainm Gaelach á phlé acu. Bhí "each uisce" ar "seahorse" ag mo dhuine ó Seahorse Ireland (tá pórú each uisce ar siuil ag an fiontar seo i gCarna)

http://www.seahorseireland.com/extendo/webstore/web2/index.jsp?page=aboutUs