RT Journal Article SR Electronic T1 Small but powerful: the oribatid mite Archegozetes longisetosus Aoki (Acari, Oribatida) produces disproportionately high forces JF Journal of Experimental Biology JO J. Exp. Biol. FD The Company of Biologists Ltd SP 3036 OP 3042 DO 10.1242/jeb.008276 VO 210 IS 17 A1 Heethoff, Michael A1 Koerner, Lars YR 2007 UL http://jeb.biologists.org/content/210/17/3036.abstract AB We investigated the holding and pulling forces generated by claws of the microarthropod Archegozetes longisetosus (Chelicerata, Acari, Oribatida) on three substrates with different roughness (Ra=0.05 μm, 1 μm, 30 μm). Holding forces were measured perpendicular to the substrate using a strain gage force transducer; pulling forces were measured parallel to the substrate using an analytical scale. We found a significant positive correlation of surface roughness and the forces generated. Mites produced holding forces on horizontal rough surfaces (Ra=30 μm) of up to 1180 times their weight; on vertical rough surfaces (Ra=30 μm) they can pull with 530 times their weight, effectively involving only two pairs of legs. The relative forces are five times higher than theoretically expected for organisms of this size (<1 mm, 100 μg) and higher than any relative forces reported for insect claws. Muscles involved in claw action produced stresses up to 1170 kN m–2, a value that is only excelled by decapod crustacean claw closer muscles. Ours is the first study of performance by chelicerate apoteles and claws and also the first to measure forces generated by any microarthropod.