Research Press Release | March 14, 2013
Key points of the research results
– A sequence of photographs of the flying behavior of squid (from jumping out of to landing on water) were taken, and the details of those actions were revealed to the world for the first time.
– It was found that squid display highly sophisticated “flying behavior” that, instead of just jumping out of water, they increase speed by jet propulsion, create lift by spreading their arms and fins and land on water by controlling the lift.
– It is considered highly likely that the flying behavior of squid has developed as a means of escaping from predators.
Overview of the research results
When the Training Ship Oshoromaru of the School of Fisheries Sciences was out at sea, a sequence of photographs of squid jumping out of and landing on water were taken. In this study, the behavior was divided into four stages, and the flying behavior was analyzed in detail. As a result, it was revealed for the first time that the behavior of squid in the air was “flight behavior,” and that they change their form and posture purposefully instead of simply jumping out of water.
Overview of the research paper presentation
Title: Oceanic squid do fly
Authors: Kouta Muramatsu (Second year of the master’s course, Graduate School of Fisheries Sciences), Jun Yamamoto (Assistant Professor, Field Science Center for Northern Biosphere), Takuzo Abe (Junior Second Officer, Training Ship Oshoro Maru), Keiko Sekiguchi (Researcher, Graduate School of Arts and Sciences, International Christian University), Naoki Hoshi (Senior Second Officer, Training Ship Oshoro Maru) and Yasunori Sakurai (Professor, Graduate School of Fisheries Sciences)
Magazine in which the paper was presented: Marine Biology (science magazine published by Springer Publishing Company in Germany)
Date of publication: February 5, 2013
Overview of the research results
Background – Squids swim using propulsive force (jet propulsion) gained by squirting water drawn into the mantle from the hyponome. When they feel predators or other enemies are approaching, they squirt water from the hyponome repeatedly to escape from the danger as soon as possible. Some pelagic species with powerful muscles are known to jump out by squirting water especially strongly. Such behavior has been witnessed throughout the world as “flying squid.” However, since it occurs when people do not expect it, most reports were fragmentary or anecdotal and it had not been determined whether it is merely jumping out of water or actual flying.
The flight behavior of squid was observed during a visual survey conducted during a training cruise of the university’s Training Ship Oshoromaru (at 14:25 on July 25, 2011, 35°34.0’ N, 146°19.3’E, approx. 600 km east of Tokyo). When the ship was navigating to the east at a speed of 12.8 knots, a shoal of some 100 squid jumped out of water twice, probably because they were surprised by the bow wave. The process from jumping out to landing on water was photographed by Kota Muramatsu (Graduate student) and Dr. Keiko Sekiguchi (Cetacean researcher of International Christian University), and the flight behavior of squid was analyzed based on these photos.
The observed squid were young (small and immature) individuals of Ommastrephidae (relative of sagittated calamary), and were thought to be neon flying squid or purpleback flying squid. They were approximately 203 to 225 mm (mantle length: 122 to 135 mm) in total length (from the tip of the fins to the tip of arms). Analysis of the sequential photos revealed that the flight behavior of squid can be divided into four stages.
◆ Jumping out: They jump out of water by squirting water. At this stage, they take up a posture to reduce water resistance by wrapping the fins around the mantle and folding the arms. It suggests that they approach the water surface by swimming fast before jumping out.
◆ Squirt: They keep squirting water from the hyponome and accelerate in the air and spread their fins and arms to create more lift. At this time, they spread the protective membrane between their arms to make a wing-like shape together with the arms. The midair moving speed at this time reaches 8.8 to 11.2 m/s.
◆ Gliding: After squirting water, they begin to glide while continuing to spread their arms and fins. The lift is created by the “wing” made of fins, arms and membrane, and they maintain a slightly upward position (pitch up) toward the direction of movement to maintain balance. Tension of the mantle is maintained and the midair posture is stabilized by withstanding the lift acting on the front and back of their bodies (fins and arms).
◆ Landing on water: They wrap the fins around the mantle and fold their arms and take up a position slightly downward (pitch down) toward the direction of movement.
As mentioned above, it was revealed that squid display highly sophisticated flight behavior instead of simply jumping out of water.
It is highly likely that the flying of squid occurs frequently as escape behavior in the seas around the world. It suggests many squid are eaten by sea birds in the air. This is thought to help understand the food chain of marine ecosystem.
Shoal of squid gliding in the air – they create lift at the front and back of their bodies by spreading their fins, arms and protective membrane.
Photographed by Kota Muramatsu (Second year of the master’s course, Graduate School of Fisheries Sciences)
Jun Yamamoto, Assistant Professor,
Hokkaido University Field Science
Center for Northern Biosphere
Press release (February 7, 2013)
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