Aviva challenges Martin and Chris to a fencing duel and tells them to Aviva challenges Martin and Chris to a fencing duel and tells them to choose their swords. The Bros can't decide, so she tells them if they choose their swords. The Bros can't decide, so she tells them if they pick their favorite billfish - swordfish, marlin or sailfish - she'll pick their favorite billfish - swordfish, marlin or sailfish - she'll make them a Creature Power Suit. So they head out on a mission to make them a Creature Power Suit. So they head out on a mission to explore the mysterious world of billfish. Science Concept: explore the mysterious world of billfish. Science Concept: Hydrodynamics - the physics of motion and action of fluids. Hydrodynamics - the physics of motion and action of fluids.