1. Morphological traits of adult Aquarius remigis and related functions .
| Morphological trait | Value | Main finding | Function | Reference |
| Data gathered from our scanning electron microscope (SEM) study, Hinton (1976), and Hu & Bush (2010). | ||||
| Deformation | ||||
| Legs | Young’s modulus: ~10 GPa | Adaptive deformation at three joints increases supporting force. | Maximizing propelling forces | Zheng et al., 2009 |
| Flexibility of each segment increases supporting force. | Maximizing propelling forces | Ji et al., 2012 | ||
| Bristles | Young’s modulus: ~10 GPa | Microscale droplets between bristles can be expelled out due to elastic deformation of bristles. | Minimizing resistant forces | Wang et al., 2015 |
| Bristle deformation during lift-up of legs reduces contact area with water, thus reducing detach force. | Minimizing resistant forces | Sun et al., 2018 | ||
| Orientation | ||||
| Legs | Unfixed | Supporting force decreases as stepping angle increases. Penetration occurs at 28°. | Maximizing propelling forces | Feng et al., 2007 |
| Midleg experiences larger stroking force as they extend perpendicularly to direction of motion. | Maximizing propelling forces | Prakash & Bush, 2011 | ||
| Hindleg experiences less drag force as they extend along direction of motion. | Minimizing resistant forces | Prakash & Bush, 2011 | ||
| Bristles | Tilt angle: 30°–50° | Droplets advance more easily toward leg tip, which is linked to a peeling mode during lift-up of legs. | Minimizing resistant forces | Prakash & Bush, 2011 |
| Grooves | Tilt angle: ~10° | Flow slips more easily in direction of grooves. | Minimizing resistant forces | Choi et al., 2006 |
| Dimensions | ||||
| Legs | Length: 1.3–1.7 μm (midleg)
Width: 90–110 μm |
Critical leg aspect ratio l/r (l: wetted length; r: radius of leg) at which supporting force reaches a plateau. | Maximizing propelling forces | Vella, 2008 |
| Bristles | Length: 20–40 μm
Width: 1.5–2 μm |
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| Grooves | Depth: ~200 nm
Width: ~400 nm |
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| Spacing | ||||
| Legs | Coxa spacing:
Foreleg-midleg: ~5 mm Midleg-hindleg: ~2 mm |
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| Bristles | 6–8 μm | Critical bristle spacing at which supporting force reaches a maximum. | Maximizing propelling forces | Xue et al., 2014 |
| Upper limit to maintain Cassie state, and lower limit to prevent bristle collision. | Minimizing resistant forces | Su et al., 2010 | ||
| Grooves | Closely packed | |||