Rocket squid! A short paper in press at Deep Sea Research II discusses a remarkable sequence of 16 photos taken by amateur photographer Bob Hulse off the coast of Brazil. The pictures show a group of small squid (Sthenoteuthis pteropus) launching themselves out of the water and flying for short distances through the air. This behavior has been seen before in squids of several species, but captured only spottily on film.
Hulse’s photos, shot in “burst” mode with a digital SLR, clearly show that the squid continue to expel water through their siphons after leaving the water. This means they continue to accelerate in the air, effectively undergoing low-altitude, water-propelled rocket flight. After using up all the water stored in their mantle (which for these guys takes less than a second), they glide back into the water on their fins and arms, which they arrange into a wing-like surface. The fins even have flaps, which are used (above and below water) like the control surfaces on an airplane’s wing.
Because the photos were shot in burst mode, they have exactly the same time interval between them, which allowed the authors to estimate squid speeds and accelerations. They could then go on to estimate the cost of transport–i.e., how much energy it takes a squid to move a certain distance–in air, and comprare it to previously-estimated numbers for squid underwater.
The results were impressive: squid can travel twice as fast in the air as in water, and their cost-of-transport above the surface is one-fifth what it is below. They speculate that flying behavior might be used during migration to save energy, not just as an evasive maneuver to escape predators. This paper doesn’t present what you’d call an exhaustive study, but it clearly documents a seldom-documented behavior, and if the authors get what they wish for in their conclusion, it will provoke more research on squid flight.
Ron O’Dora, Julia Stewart, William Gilly, John Payne, Teresa Cerveira Borges, & Tierney Thys (2012). Squid rocket science: How squid launch into air Deep Sea Research II DOI: 10.1016/j.dsr2.2012.07.002