Um…I'd like to add a bit to those name origin things...
-The "followed by a random 'u'" thing is kinda necessary in the japanese language since there are no syllables that end with 'r'. They have to settle for 'ru' which is the closest they've got to an actual 'r' sound.
-Shimama probably comes from 'shimauma' which means zebra (literally, 'striped horse').
-Hihidaruma is probably a combination of 'hihi' (baboon, like Dogasu said), and 'daruma' (Daruma doll, famous Japanese toy). The fire typing probably comes from 'hihi' which can also mean 'fire fire' in japanese.
-'Pigeon' is actually 'hato' in japanese.
-Meguroko seems to me like a combination of 'megane' (glasses) and 'kuroko' (croco) since it looks like it's wearing glasses.