Orca seems to be a dead end. I looked for words that could be made with the remaining letters, but the only animals I found were PIKA and PEBA. I have never even heard of a peba, but apparently it's a long-nosed armadillo, and the game didn't recognize it anyway.
With these letters you could get a pair of snakes, BOA and KRAIT, but KRAIT wasn't accepted either.
KOI and CARP is another funny pair because a koi is a carp.
I've only found one trio of animals so far, and I'm ready to give up on finding the rest.