Scopula

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Scopula pads (pl. 'scopulae') are tufts of hair at the end of a tarantulas legs and pedipalps. They comprise of microscopic hairs, each covered in even smaller hairs called setules. The result is a massive surface area.

When the scopulae are splayed out and placed against a surface, remarkable adhesion is produced due to the van der Waals force, which is an attractive force acting between individual molecules. This enables spiders with scopulae to climb even sheer, smooth surfaces such as glass. The adhesion is so great that the spider could grip using this force and support 170 times its own weight.

Scopulae are found in addition to, not instead of, two claws at the end of each appendage, called tarsal claws. They do not occur on all spiders.