Defense: Their most obvious purpose is defense. The sharp, pointed needles deter predators by making them difficult to grab and swallow. When threatened, a hedgehog will curl into a tight ball, presenting a formidable wall of needles to any would-be attacker.
Camouflage: In some environments, the needles can provide camouflage by blending in with the surrounding vegetation.
Thermoregulation: The needles also play a role in thermoregulation. During cold weather, they can trap a layer of air close to the skin, helping to insulate the hedgehog and keep it warm.
Communication: While not fully understood, there is some evidence that hedgehogs may use their needles for communication. The way they raise or lower their spines can convey information to other hedgehogs, perhaps signaling alarm or social status.
Overall, hedgehog needles are a complex and multifaceted adaptation that contributes significantly to their survival and well-being.