Squids use a flexible nozzle that acts like an elastic battery to boost their jet power by over 300%.
A squid's siphon is a compliant energy storage device that lags behind the contraction of its body to amplify propulsion. This mechanism acts as an elastic capacitor, storing and then releasing energy to maximize the force of each water jet. Biologists previously thought the siphon was just a simple tube for directing water. This discovery shows that the squid's anatomy is far more mechanically efficient than human-made underwater jets. Engineers are now looking to copy this design to create ultra-efficient soft robots for ocean exploration. It proves that nature solved the problem of high-speed underwater travel long before we did.
Squid-inspired soft superpropulsion
arXiv · 2605.03239
Squid span four orders of magnitude in size yet rely on pulsed jets. We show that the funnel (siphon) is a compliant nozzle whose dilation and recoil lag mantle contraction, storing and returning energy within each pulse, a mechanism we term superpropulsion. Histology reveals a collagen sheath, and chromatophore tracking in two squid species quantifies a repeatable phase lag. Engineered nozzles, 3D fluid-structure simulations, and a reduced-order mathematical model predict > 300% impulse amplifi