Reorientation of daffodil( Narcissus : Amaryllidaceae) flowers inwind: drag reduction andtorsional flexibility

Perhaps the most striking feature of billfishes is the extreme elongation of the premaxillary bones forming their rostra. Surprisingly, the exact role of this structure in feeding is still controversial. The goal of this study is to investigate the use of the rostrum from a functional, biomechanical and morphological standpoint to ultimately infer its possible role during feeding. Using beam theory, experimental and theoretical loading tests were performed on the rostra from two morphologically different billfish, the blue marlin (Makaira nigricans) and the swordfish (Xiphias gladius). Two loading regimes were applied (dorsoventral and lateral) to simulate possible striking behaviors. Histological samples and material properties of the rostra were obtained along their lengths to further characterize structure and mechanical performance. Intraspecific results show similar stress distributions for most regions of the rostra, suggesting that this structure may be designed to withstand continuous loadings with no particular region of stress concentration. Although material stiffness increased distally, flexural stiffness increased proximally owing to higher second moment of area. The blue marlin rostrum was stiffer and resisted considerably higher loads for both loading planes compared with that of the swordfish. However, when a continuous load along the rostrum was considered, simulating the rostrum swinging through the water, swordfish exhibited lower stress and drag during lateral loading. Our combined results suggest that the swordfish rostrum is suited for lateral swiping to incapacitate their prey, whereas the blue marlin rostrum is better suited to strike prey from a wider variety of directions.

Section: Discussionmentioning

confidence: 99%

Feeding in billfishes: inferring the role of the rostrum from a biomechanical standpoint

Habegger

Dean

Dunlop

et al. 2015

“…A number of studies support the idea that flexibility allows for reconfiguration of biological structures, which results in reduced drag forces experienced by the organisms (e.g. Alben et al, 2002;Alben et al, 2004;Denny, 1994; Etnier and Flexible clap and fling Vogel, 2000;Koehl, 1984;Vogel, 1989). The basic idea in these cases is that the force on the body produced by the moving fluid causes the flexible body to bend or reconfigure, which, in turn, reduces the force felt by the body.…”

Section: Introductionmentioning

confidence: 97%

Flexible clap and fling in tiny insect flight

Miller

Peskin

2009

148

146

SUMMARYOf the insects that have been filmed in flight, those that are 1 mm in length or less often clap their wings together at the end of each upstroke and fling them apart at the beginning of each downstroke. This ʻclap and flingʼ motion is thought to augment the lift forces generated during flight. What has not been highlighted in previous work is that very large forces are required to clap the wings together and to fling the wings apart at the low Reynolds numbers relevant to these tiny insects. In this paper, we use the immersed boundary method to simulate clap and fling in rigid and flexible wings. We find that the drag forces generated during fling with rigid wings can be up to 10 times larger than what would be produced without the effects of wing-wing interaction. As the horizontal components of the forces generated during the end of the upstroke and beginning of the downstroke cancel as a result of the motion of the two wings, these forces cannot be used to generate thrust. As a result, clap and fling appears to be rather inefficient for the smallest flying insects. We also add flexibility to the wings and find that the maximum drag force generated during the fling can be reduced by about 50%. In some instances, the net lift forces generated are also improved relative to the rigid wing case. Supplementary material available online at

“…upward-facing flowers) that allow pollinators to approach from many directions (Fenster et al, 2009). Wind, already known to have important direct effects on flower reorientation (Etnier and Vogel, 2000), might add another dimension of complexity to the interaction between flowers and their pollinators.…”

Section: Effects Of Wind On Floral Approach Anglementioning

confidence: 99%

Wind alters landing dynamics in bumblebees

Chang

Crall

Combes

2016

Landing is an important but understudied behavior that flying animals must perform constantly. In still air, insects decelerate smoothly prior to landing by employing the relatively simple strategy of maintaining a constant rate of image expansion during their approach. However, it is unclear whether insects employ this strategy when faced with challenging flight environments. Here, we tested the effects of wind on bumblebees (Bombus impatiens) landing on flowers. We find that bees' approach paths to flowers shift from multidirectional in still air to unidirectional in wind, regardless of flower orientation. In addition, bees landing in a 3.5 m s −1 headwind do not decelerate smoothly, but rather maintain a high flight speed until contact, resulting in higher peak decelerations upon impact. These findings suggest that wind has a strong influence on insect landing behavior and performance, with important implications for the design of micro aerial vehicles and the ecomechanics of insect flight.