In essence, a furcula is a long, rigid stick, held underneath the body at high tension. When the springtail releases that pressure, the stick pushes down into the ground, or even the water's surface, like an upside-down medieval catapult, firing the springtail into the air in a semi-controlled manner.
2022, Thomas Halliday, Otherlands, Penguin, published 2023, page 215