The Worms can jump in many different ways, you've got to learn them all if you want to get over those obstacles!
Jump: Press Jump1 once, the Worm will jump forwards.
Back Jump: Press Jump1 twice in quick succession, the Worm will hop backwards.
Jump on Spot: Press Jump2 once, the Worm will jump on the spot.
Back Flip: Press Jump2 twice in quick succession, the Worm will do a back flip.
Small Back Flip: Press Jump2 twice, and then Jump1 quickly, the Worm will do a smaller back flip.