在沙漠中生活的沙魚蜥（Scincus scincus，如上圖）就像它的名字一樣生活,。它們能夠鉆到沙丘的下面，并且在沙下“游泳”，從而避開天敵和炎熱,，同時(shí)悄悄靠近獵物。但是這種10厘米長(zhǎng)的爬行動(dòng)物究竟如何穿越這些沙粒的表層呢,？
據(jù)美國(guó)《科學(xué)》雜志在線新聞報(bào)道,，高速X射線成像結(jié)果顯示，這種蜥蜴會(huì)縮攏它們的四肢,，并通過(guò)Z字型地左右搖擺身體來(lái)推動(dòng)自己在沙子上前進(jìn),，其像魚或蛇一樣擺動(dòng)身體前行的速度能夠達(dá)到每秒鐘15厘米。這一發(fā)現(xiàn)將幫助科學(xué)家搞清沙漠中的其他居民——例如蝎子和蛇——是如何在沙子下行動(dòng)的,。研究人員在7月17日出版的美國(guó)《科學(xué)》雜志上報(bào)告了這一發(fā)現(xiàn),。（生物谷Bioon.com）
生物谷推薦原始出處：
Science 17 July 2009:DOI: 10.1126/science.1172490
Undulatory Swimming in Sand: Subsurface Locomotion of the Sandfish Lizard
Ryan D. Maladen,1 Yang Ding,2 Chen Li,2 Daniel I. Goldman1,2,*
The desert-dwelling sandfish (Scincus scincus) moves within dry sand, a material that displays solid and fluidlike behavior. High-speed x-ray imaging shows that below the surface, the lizard no longer uses limbs for propulsion but generates thrust to overcome drag by propagating an undulatory traveling wave down the body. Although viscous hydrodynamics can predict swimming speed in fluids such as water, an equivalent theory for granular drag is not available. To predict sandfish swimming speed, we developed an empirical model by measuring granular drag force on a small cylinder oriented at different angles relative to the displacement direction and summing these forces over the animal movement profile. The agreement between model and experiment implies that the noninertial swimming occurs in a frictional fluid.
1 Interdisciplinary Bioengineering Program, Georgia Institute of Technology, Atlanta, GA 30332, USA.
2 School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA.
