A hedgehog is any of the spiny mammals of the subfamily 'Erinaceinae', in the family 'Erinaceidae'. There are seventeen species of hedgehog in five genera found through parts of Europe, Asia, and Africa, and in New Zealand by introduction. There are no hedgehogs native to Australia and no living species native to the Americas (the extinct genus 'Amphechinus' was once present in North America).

If a hedgehog falls toward the ground, it keeps itself safe by rolling into a ball to surround itself with “spines” that absorb the impact. It’s an effective method of protection. Hedgehog spines are colloquially referred to as "quills".

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