Locomotor transition: how squid jet from water to air

Abstract

The amazing multi-modal locomotion of flying squid helps to achieve fast-speed migration and predator-escape behavior. Observation of flying squid has been rarely reported in recent years, since it is challenging to clearly record the flying squid’s aquatic-aerial locomotion in a marine environment. The existing reports of squid-flying events are rare and merely record the in-air motion. Therefore, the water-air locomotor transition of flying squid is still unknown. This paper proposes the idea of using CFD to simulate the process of the flying squid (Sthenoteuthis oualaniensis (S. oualaniensis)) launching from water into air. The results for the first time reveal the flow field information of squid in launching phase and show the kinematic parameters of flying squid in quantification. Both a trailing jet and pinch-off vortex rings are formed to generate launching thrust, and the formation number L ω /D ω is 5.22, demonstrating that the jet strategy is to produce greater time-averaged thrust rather than higher propulsion efficiency. The results also indicate that the maximum flying speed negatively correlates with the launch angle, indicating that a lower launch angle could result in a larger flying speed for the flying squid to escape. These findings explore the multi-modal locomotion of flying squid from a new perspective, helping to explain the trade-off strategy of water-to-air transition, and further enhance the performance of aquatic-aerial vehicles.

Cool your jets: biological jet propulsion in marine invertebrates

“…However, to further elucidate the underlying mechanisms of aquatic jet propulsion, we need robust data in a comparative framework and the development of model species that can provide access to quantifying body-fluid interactions both inside and outside of the body cavity. To allow for better comparative data, a combination of rapidly evolving new methods, such as computational fluid dynamics (Krieg and Mohseni, 2013;Hou et al, 2020;Luo et al, 2020), robotics (Marut et al, 2012;Giorgio-Serchi et al, 2016), in situ diveroperated PIV (Sutherland et al, 2014) and even genetic techniques that can eliminate pigmentation in opaque jetting species (Crawford et al, 2020), will be crucial for success.…”

Biorobotic Waterfowl Flipper with Skeletal Skins in a Computational Framework: Kinematic Conformation and Hydrodynamic Analysis

“…[21] For computational implementations, several new nonintrusive approaches have been applied to study biomimetic aquatic locomotion, which integrate measured kinematics with computational fluid dynamics (CFD). [22][23][24] Among them, the cardinal is to synthesize the anatomically biomechanical characteristics and comprehensive biomimetic locomotion sequences with an impeccable reality. [25] In our recent research, we quantitatively analyzed the 3D maneuvering trajectories of the flipper with underwater stereo-videography.…”

Genomes of Two Flying Squid Species Provide Novel Sights into Adaptations of Cephalopods to Pelagic Life

“…Common pelagic cephalopods include members of the Ommastrephidae (Teuthida, Decapodiformes) called flying squids, that can jump out of the water and in some cases glide more than 30 m in the air [20]. They can achieve the fastest recorded speed (∼ 8 m s −1 ) of any aquatic invertebrates [21, 22]. Important taxa with such capabilities include the purpleback flying squids ( Sthenoteuthis spp.)…”

“…Important taxa with such capabilities include the purpleback flying squids ( Sthenoteuthis spp.) [21, 23, 24]. These are the most abundant large squids in the tropical and subtropical Indo-Pacific ocean, found at depths from the surface to more than 600 m [2].…”