Marine biologist Silvia Maciá was boating on the north coast of Jamaica in the summer of 2001 when she noticed something soar out of the sea. At first she thought it was a member of the flying fish family—a group of marine fish that escape predators by breaking the water's surface at great speed and gliding through the air on unusually large pectoral fins. But after tracing the creature's graceful arc for a few seconds, Maciá realized this was no fish. It was a squid—and it was flying.

With her husband and fellow biologist Michael Robinson, Maciá identified the airborne cephalopod as a Caribbean reef squid (Sepioteuthis sepioidea)—a lithe, torpedo-shaped critter with long, undulating fins. They think the squid was startled by the noise of the boat's outboard engine and estimated that the 20-centimeter-long mollusk reached a height of two meters above the water and flew a total distance of 10 meters—50 times its body length. What's more, the squid extended its fins and flared its tentacles in a radial pattern while airborne, as though guiding its flight.

"It was doing this weird thing with its arms where it had them spread out almost in a circle," recalls Maciá, who teaches at Barry University in Florida. "It had its fins kind of flared out as much as it could—it really looked liked it was flying. It hadn't accidentally flopped out of the water; it was maintaining its posture in a certain way. It was doing something active."

Squid surveillance
On a LISTSERV dedicated to mollusks, Maciá and Robinson (University of Miami), called out for any other researchers who had witnessed airborne squid—a phenomenon the husband and wife had not personally observed before. Maciá and Robinson received numerous replies from scientists with whom they eventually co-wrote a study in 2004 in the Journal of Molluscan Studies. The paper collects sightings of at least six distinct squid species squirting themselves out of the ocean and over the waves, sometimes solo, sometimes in packs—sometimes with enough force to match the speed of boats or wind up on decks. But the paper includes no photographs or video clips; its evidence is largely anecdotal. The fact is that documented instances of flying squid are incredibly rare. Most people are unprepared for such a sight.

Recently, however, on a cruise ship off the coast of Brazil, retired geologist and amateur photographer Bob Hulse captured what may be the best-ever photographic evidence of flying squid. Hulse sent the pictures to University of Hawaii oceanographer Richard Young, who passed them along to Ron O'Dor, senior scientist for the Census of Marine Life. O'Dor thinks he can analyze the photos to gain a better understanding of squid aerodynamics, which few people have been able to properly study due to lack of adequate documentation.

"Hulse was shooting with burst mode on his camera, so I know exactly what the interval is between the frames and I can calculate velocity of squid flying though the air," O'Dor says. "We now think there are dozens of species that do it. Squid are used to gliding in the water, so the same physiology probably allows them to maneuver and glide in the air. When you look at some of the pictures, it seems they are more or less using their fins as wings, and they are curling their arms in [a] shape that could easily be some kind of lifting surface."

From fin to wing
The 2004 paper's authors argue that "gliding" is too passive a term to describe what squid do when they leave the ocean for the air: "flight" is more fitting.

"From our observations it seemed like squid engage in behaviors to prolong their flight," Maciá says. "One of our co-authors saw them actually flapping their fins. Some people have seen them jetting water while in flight. We felt that 'flight' is more appropriate because it implies something active."

The aerodynamic benefit an airborne squid derives from flapping fins and spiraled tentacles is not clear, but some researchers hypothesize that these behaviors provide extra lift and help stabilize the squid when out of its primary element. In the water some squid spread their tentacles into a weblike pattern that facilitates swimming backward—a trick they could try to mimic in the air to gain an extra set of wings, some scientists have proposed. And rapidly changing the position of the tentacles could even function as a kind of brake.

Some squid don't rely on such subtle aerial acrobatics. Instead, like the squid photographed by Hulse, they forcibly propel themselves through the air. Some 370 kilometers off the coast of Sydney, Australia, one of the 2004 paper's co-authors witnessed a skipjack tuna chasing hundreds of what were probably arrow squid (Nototodarus gouldi). The school repeatedly leapt out of the ocean, spurting jets of water behind them as they flew through the air. Some arrow squid reached a height of three meters and flew a total distance of eight to 10 meters.

Fight or flight
For all these flying squid species, jet propulsion is the key for getting out of the water in the first place. First, a squid expands its mantle—the cloak of soft muscular tissue that surrounds its body—which fills with water. Then the squid quickly contracts it to send the trapped water shooting through a flexible tube below its head, called the funnel or siphon. By changing the position of this funnel, a squid can propel itself in almost any direction. Underwater, squid use jet propulsion to pounce on swift prey and escape intimidating predators. But sometimes jetting through the currents is not enough to make a successful getaway—sometimes, a squid needs to get out of the water altogether. So they fly.

Biologists still do not fully understand the mechanics of squid aeronautics, but based on accumulating anecdotal and photographic evidence, they have no doubt that the phenomenon is real and widespread. "Flying is not at all unusual in several families of squid," says Michael Vecchione, a squid expert at the Smithsonian Institution. In particular, the families Ommastrephidae and Onychoteuthidae are known for their loftiness. "It's not uncommon to find squid on the deck of the ship in the morning," Vecchione adds. Many squid remain in the dark depths during the day to avoid predators, Vecchione explains, but when they venture into shallower waters at night to feed they are liable to jump out of the water in a panic and onto a boat.

These morning-after encounters are not infrequent, but catching a squid in the act of flight is still quite a feat. "It just happens so fast," Maciá says. "You really have to be in the right place in the right time."

Pictures of flying squid courtesy of Bob and Deb Hulse, who took the photos off the coast of Brazil. Ron O'Dor, senior scientist for the Census of Marine Life, and University of Hawaii oceanographer Richard Young think the squid are orangeback flying squid (Sthenoteuthis pteropus), although a colleague at the Smithsonian thinks they might be Argentine shortfin squid (Illex argentinus).