BIOMECHANICS

Holding Tight, Letting Go

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Science  01 Jun 2001:
Vol. 292, Issue 5522, pp. 1611
DOI: 10.1126/science.292.5522.1611b

Ants appear to be oblivious to the orientation of surfaces; they run across the undersides of leaves and other smooth terrain. How do they adhere (supporting many times their own body weight), and how do they do so in a rapidly reversible manner.

Federle et al. have performed anatomical and biomechanical observations of the Asian weaver ant, Oecophylla smaragdina. The arolium is a flexible adhesive pad located between the claws. With each step, the claws are retracted by the flexor tendon if they do not catch on surface irregularities; this movement extends the arolium and expands it hydraulically with fluid from the arolium gland reservoir. The applied pressure was determined to lie in the range of 10 to 15 kilopascals. Elastic recoil of the arolium cuticle then shunts the fluid back into the gland, allowing facile detachment. — GJC

Proc. Natl. Acad. Sci. U.S.A.98, 6215 (2001).

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