Why Do Spiders Have Hair?

Most people are aware that spiders, or tarantulas, have evolved a furry appearance for self-defense purposes. Tarantulas possess what are called urticating hairs. When a tarantula feels threatened it will fling its hairs at it enemy, which causes severe allergic reactions in humans. But this is not the only purpose that tarantula fuzz serves.

Tarantulas also have fine hairs on their bodies called trichobothria, which is like their own type of ears. Since spiders do not have ears, and cannot hear sounds like we do, they instead use these hairs to sense vibrations that tell them about their surroundings. These hairs are so delicate that they can pick up air movement right down to one billionth of a meter. These hairs can discern between movement and background noise, and can sense sounds between 40 and 600 Hz.

Spiders can also smell and taste potential predators with their hairs, which helps them assess if their trapped prey would make a decent meal. And I thought they had all that hair to make humans run from them.

Are there any spiders that do not have any hair at all?