Tarantulas Shoot Silk From Their Feet, Researchers Find

Talk about fancy footwork!

British researchers have discovered that adult tarantulas can climb sheer walls by shooting strands of silk from their feet -- enabling the hefty arachnids to save themselves should they risk falling from a height. Tarantulas, it turns out, are actually quite fragile.

'The animals are very delicate. They wouldn't survive a fall from any height," explained Claire Rind from the University of Newcastle in the U.K. Teaming up with undergraduate Luke Birkett, Rind made the surprising discovery using three ground-dwelling Chilean rose tarantulas.

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.

"People said tarantulas couldn't stay on a vertical surface," Rind said of the relatively hefty creatures, which can grow to a tenth of a pound in weight. When the spider didn't fall, the duo gave the aquarium a gentle shake. The tarantula slipped slightly, but soon regained its footing.

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 where the spider had stood before slipping.

Where on the spiders' feet was the silk coming from? Rid took molted exoskeletons from her Mexican flame knee tarantula, Fluffy, when she was young, Rind looked at them with a microscope and could see minute threads of silk protruding from microscopic hairs on Fluffy's feet.

Next, the team took a closer look at moults from Fluffy, the Chilean rose tarantulas and Indian ornamental tarantulas with scanning electron microscopy and saw minute reinforced silk-producing spigots, which extended beyond the microscopic attachment hairs on the spiders' feet, widely distributed across the foot's surface.

Rind also looked at the tarantula family tree, and found that all three species were only distantly related; all tarantula feet most likely produce the life-saving silk.

The article was published in The Journal of Experimental Biology.