Uhm...Jak, a penguin
is a bird. I know you know, but did you know you started off with bird as a group and then you went to sub-class..specific bird.
It should go from class to class such as; flighty as an eagle, grounded as an emu.
Yea...I picked a different class cause penguins in a way fly through a medium such as water. I know its not flying, but it does use its wing like flippers to glide through water like eagles soar through the air.
An emu can only run and therefore is a grounded bird. Sorry.