How do you defeat the octopus in super monkey ball banana blitz?

You have to run into the back of its head to inflict damage. However, you may accidentally fall into the water if you're not careful. The octopus will also try and slap you with its tentacles or spray ink. It may also try to pull you underwater with it. Keep trying, and eventually, you will unlock world 6 and its singing diva of a boss. Defeat it by attacking its microphone and avoiding its singing, which can make your monkey dizzy, and the boulder shower, which can cause you to fall out, and unlock world 7. Defeat the harlequin monkey (mouse?) by running into it a few times and avoiding the balls that make up what it attacks with, and unlock world 8. Defeat the pirate that you saw steal the golden banana bunch by attacking its bottom and then you will have all 8 golden bananas. Afterward, try unlocking worlds 9 and 10, which are very very hard. Good luck!