Petite dimples
Scidea TOS
tos20061009
Nature 437 (7059), 733-736 (2005). | Abs . FigureTable | CrossRef
NPG Printed 20050929 doi: 10.1038/nature.03995
Petite dimples
Hydrometra: intimate exchange 2006
Credit: Scidea Art 2006 Source: www.ScideaNews.com
Many beautiful silhouettes of water-surface insects can be found in John Bush's website.
When those insects elegantly stand on the water surface, the enigma is not just their reflections. We have understood their plane-moving skills and why they will not sink [ 1a , 1b ]. Walking on the legs decorated with multiscale porous microtextures, the bended water surface can provide enough tension along with flotage to support their tiny weights. We know that we can walk due to ground friction, but what are the meniscus-climbing skills for water-surface insects such as Mesovelia, Microvelia and Hydrometra and beetle larvae Pyrrhalta ( * )?
On 29 September 2005 in Nature [ 2 ], David L. Hu and John W. M. Bush from MIT gave the answers by theoretically analyzing of the movements recorded by a high-speed video camera (500 frames/s). Although these millimeter-scale insects small relative to the capillary length of water ( * 0.27 cm) are unable to climb a meniscus using their traditional means of propulsion, they have developed a solution for ascent. Before meniscus-climbing, they jump and deform the surface of water with the legs (Mesovelia) or twist with its body to bend the surface (Pyrrhalta) at first, then they assume a fixed body posture; the capillary force due to bended surface propel them laterally to climb meniscus along the shore.
The water-surface creatures can sense what a better posture is for fast propeling. How surprising the instantaneous feelings are! The developed force sensors may locate within their magic feet, arthroses (as Mesovelia, Microvelia and Hydrometra ), abdomen (as beetle larva Pyrrhalta ) or certain region of the body. This is a open question but thanks are due to nature but just evolution.
Data Notes
* Capillary length of water: Lc = (σ/ρg)0.5 =0.27 cm, where σ = 70 dynes/cm is the surface tension, ρ = 1g/cm3 the water density, and g = 980 cm/s2 the gravitational acceleration.
* Typical bodies' lengthes: Mesovelia: 8 mm; Microvelia: 2 mm; Hydrometra: 11 mm; beetle larvae Pyrrhalta: 6 mm.
Lin Pu is in the Physics Department of Nanjing University, Nanjing 210093, CHINA.
References
1a | Gao, X. & Jiang, L. |
| 1b | Dickinson, M. H.; Farley, C. T.; Full, R. J.; Koehl, M. A. R.; Kram, R. & Lehman, S. How animals move: An integrative view. Science 288, 100–106 (2000). ♦ doi: 10.1126/science.288.5463.100 | CrossRef ♦ AAAS :: Abs . Full . PDF |
| 2 | Hu D.L. & Bush J. W. M. Meniscus-climbing insects. Nature 437 (7059), 733–736 (2005). ♦ doi: 10.1038/nature.03995 | CrossRef ♦ NPG :: Abs . FigureTable . Full . PDF. Supp.Info. |
Citation
L. PU
Lin PU. Petite dimples. Scidea Sketch 1 (1), ss20050929a2 (2007).
♦ doi: 10.3128/ss20050929a2 | Scidea :: Abs . Full | CrossRef♦ Scidea Sketch ISSN: 1992 - 8548