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How do squid fins help with swimming and hovering?

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A blue-ringed octopus with bright blue rings on its beige body crawls over a rocky, coral-strewn seabed. — cephalopod Blue-ringed octopus (genus *Hapalochlaena*).

Squid fins are primarily utilized for slow movement and hovering rather than high-speed travel. These fins facilitate locomotion through the rapid undulation of their outer edges. While jet propulsion—powered by the mantle and funnel—is the primary method for quick, powerful movements, the fins provide the necessary control for more delicate positioning.1

When a squid engages in rapid jetting, it typically curls its fins tightly against the mantle to reduce drag. Conversely, for species like certain squids that are capable of gliding through the air to escape predators, the fins are expanded to act as surfaces for flight. In other cephalopods, such as cuttlefish, fins are used more frequently than jet propulsion to maintain a hovering position or to navigate near the seafloor.1