Octoper OA

Octoper OA (オクトーパーＯＡ) (Octoboss in Mega Man for Game Gear) is a giant octopus robot that appears as the sub-boss in Wave Man's stage, while Mega Man is using the marine bike. It bobs up and down in the water, and can only be damaged in the green core on his forehead. When its face appears, it will shoot energy balls from its mouth. The Octoper OA in the Mega Man for Game Gear is smaller than the one in Mega Man 5 on the NES.

Trivia

 * Its name is a modification of the word octopus, and is similar to the word October (オクトーバー). Because of this, his name is mistranslated October in the Navi Mode of Mega Man: Anniversary Collection.
 * It would also have been able to attack with a tentacle, but this was removed from the game.