https://scholar.dgist.ac.kr/handle/20.500.11750/11732 Sat, 04 Apr 2026 19:42:56 GMT 2026-04-04T19:42:56Z https://scholar.dgist.ac.kr/handle/20.500.11750/59947 Title: Comparison of thrust-generation strategies, midleg microstructures, and their functions in small water striders: Metrocoris histrio (Halobatinae) and Gerris latiabdominis (Gerrinae) Author(s): Lee, Jeongseop; Bang, Sang Yun; Kim, Woojoo; Jablonski, Piotr Grzegorz; Lee, Sang-im Abstract: Water strider (Gerridae) legs are covered with diverse setae providing hydrophobicity. It is understood theoretically how a layer of setae helps in supporting an insect and producing thrust by deforming the water surface with midleg strokes in a striding motion. However, little is known about the specific roles of diverse setae and how thrust-generation behaviour differs between species in different water flow conditions. We compared the microstructures and the use of the midlegs in standing and striding behaviour between Metrocoris histrio and Gerris latiabdominis, representing separate evolutionary lineages from fast-flowing/turbulent (Halobatinae) and slow-flowing/stagnant (Gerrinae) waters, respectively. The differences involve quicker attainment of higher maximal leg speed facilitated by an initially short wetted midleg, and a more asymmetric midleg dimple leading to faster body speed and acceleration in species living on fast-flowing water, where frequent fast strides are needed to counter the water current. We propose that these two species differ in how deeply the water surface penetrates the layer of setae and how it interacts with different microstructures during the thrust stroke. Our findings draw attention to unexplored functions of diverse microstructures on the ventral surface of the midlegs in water striders from different habitats, which have not been reflected fully in current models of semiaquatic insect hydrodynamics. Sun, 31 Aug 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/59947 2025-08-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59944 Title: Distinct kinematics and micromorphology for symmetrical rowing and sliding on water in ripple bugs and water striders Author(s): Bang, Sang Yun; Kim, Woojoo; Lee, Jeongseop; Park, Jinseok; Khare, Versha; Lee, Sang-im; Jablonski, Piotr Grzegorz Abstract: Semiaquatic bugs evolved two different propulsion mechanisms for their symmetrical rowing: a drag-based propulsion in Veliidae and a surface-tension-based propulsion in Gerridae. However, the comparative leg micromorphology and kinematics underlying these two mechanisms remain underexplored. In this study, we compared leg micro- and nanostructures and kinematics of Rhagovelia distincta (Veliidae), which employs midleg fans as oar-like blades for drag-based thrust, with Gerris latiabdominis (Gerridae), which uses long midlegs for surface-tension-based thrust. R. distincta move their midlegs in short strokes and deployed fans which function as "leaky paddles" with higher anteroposterior rigidity, inferred from seta and setula structure, exploiting drag and potentially lift. Fan protraction into the water appeared to require muscle control, while elastocapillarity may contribute to fan shaping. In contrast, G. latiabdominis exhibited longer strokes with midlegs covered with dense hydrophobic hairs suited for surface-tension-based propulsion. Ventral setae on tarsal section producing surface-tension-based-thrust formed longitudinal rows-and-gaps in both species, with posterior rows particularly robust and nano-grooved in G. latiabdominis. Additionally, both formed ventral beam-like structures from overlapping flat-tipped setae on hindlegs and forelegs which are used for support and sliding. These findings generate new hypotheses for refining models of locomotion on water surface by insects with their micro/nano-morphological diversity. Sun, 30 Nov 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/59944 2025-11-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59038 Title: Empirical evidence for the functional benefit of intra-specific wing shape variation in a sedentary bird, the Oriental Magpie (Pica serica) Author(s): Chae, Seokbong; Hwang, Jusun; Choe, Jae Chun; Jablonski, Piotr G.; Lee, Sang-im; Kim, Jooha Abstract: This study investigates the intraspecific variation in wingtip shape and its effects on aerodynamic forces and flight capabilities with the Oriental Magpies as a model species. Characterized by short and rounded wings, Oriental Magpies are highly sedentary and exhibit wingtip shape variations between juveniles and adults, as well as between males and females due to physiological changes during breeding. Analysis of 115 individuals revealed a significant interaction between sex and age in the location of the wingtip, with adult females exhibiting wings with backward-shifted wingtips than other sex and age categories. In order to examine the functional aspect of this pattern of variation, we conducted wind tunnel experiments and measured the aerodynamic performances of three wings by varying the position of wingtip from forward to backward. The results show that wings with backward-shifted wingtips have higher lift coefficient compared to wings with forward-shifted wingtips, especially at low free-stream velocities. Our findings suggest that wings with backward-shifted wingtips enhance maneuverability during both turning- and straight-flight conditions, particularly during slow gliding flight. We hypothesize that aerodynamic benefits of the backward-shifted wingtips are more important for adult females, who has increased body weight with center of mass shifted to rear part of the body due to fully developed reproductive organs including eggs and follicles. Our results suggest that age- and sex-dependent wingtip shape change can be fine-tuned according to intraspecific variation in the ecological requirements of the individuals. Thu, 31 Jul 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/59038 2025-07-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/57794 Title: Physics of sliding on water explains morphological and behavioural allometry across a wide range of body sizes in water striders (Gerridae) Author(s): Kim, Woojoo; Lee, Jae Hong; Pham, Thai Hong; Tran, Anh Duc; Ha, Jungmoon; Bang, Sang Yun; Lee, Jeongseop; Jablonski, Piotr G.; Kim, Ho-Young; Lee, Sang-im Abstract: Laws of physics shape adaptations to locomotion, and semiaquatic habitats of water striders provide opportunities to explore adaptations to locomotion on water surface. The hydrodynamics of typical propelling with symmetrical strokes of midlegs is well understood, but the subsequent passive sliding on surface has not been explored. We hypothesized that morphological and behavioural adaptations to sliding vary by body size. Based on empirical observations of water striders across a wide range of body size, we constructed a theoretical model of floating and resistance during sliding. Our model predicts that large water striders are too heavy to support anterior body on forelegs during sliding when their two midlegs are off the surface symmetrically during a recovery phase after stroke in symmetric gait. Heavy species should either (i) develop sufficiently long forelegs to support their anterior body on surface during symmetric gait or (ii) use asymmetric gait when one forward-extended midleg supports anterior body. Observations were consistent with these predictions. Additionally, medium-sized insects were observed to switch between symmetrical and asymmetrical gait in the manner that reduces sliding resistance. Our results illustrate how habitat-specific physical processes cause morphological and behavioural diversity associated with body size among biological organisms. © 2024 The Author(s). Sat, 30 Nov 2024 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/57794 2024-11-30T15:00:00Z