Climbing is possibly one of the riskiest things an adult tarantula can do. Weighing in at anything up to 50gm, the dry attachment systems that keep daintier spiders firmly anchored are on the verge of failure in these colossal arachnids. 'The animals are very delicate. They wouldn't survive a fall from any height,' explains Claire Rind from the University of Newcastle, UK. In 2006, Stanislav Gorb and his colleagues published a paper in Nature suggesting that tarantulas may save themselves from falling by releasing silk threads from their feet. However, this was quickly refuted by another group that could find no evidence of the silk. Fascinated by spiders and intrigued by the scientific controversy, Rind decided this was too good a challenge to pass up and discovered that tarantulas shoot silk from their feet when they lose their footing. She publishes her results in The Journal of Experimental Biology at http://jeb.biologists.org/content/214/11/1874.abstract.
Teaming up with undergraduate Luke Birkett, Rind tested how well three ground-dwelling Chilean rose tarantulas kept their footing on a vertical surface. Gently placing one of the animals in a very clean aquarium with microscope slides on the floor, the duo cautiously upended the aquarium to see if the tarantula could hang on. 'Given that people said tarantulas couldn't stay on a vertical surface, we didn't want to find that they were right,' remembers Rind. But the spider didn't fall, so the duo gave the aquarium a gentle shake. The tarantula slipped slightly, but soon regained its footing. So the spider had held on against the odds, but would Rind find silk on the microscope slides?
Looking at the glass by eye, Rind couldn't see anything, but when she and Birkett looked closely under a microscope, they found minute threads of silk attached to the microscope slide where the spider had stood before slipping.
|Contact: Kathryn Knight|
The Company of Biologists