The spikes on hedgehogs' backs are extremely valuable to their well-being and safety in the wild. The prickly things don't exactly feel too wonderful to touch, and as a result often keep worrying predators at bay. When hedgehogs face danger, they let their spikes stand up. This makes their bodies thorny. After they stand their spikes up, they position their bodies into tight and compact balls. This shields their vulnerable stomachs from possible attack. When hedgehogs are in ball form, not only do they feel disagreeable to the touch, they also are difficult to access.