在广袤的自然界中，生物们为了生存和保护自己，发展出了各种各样的防御机制。其中，刺猬以其独特的自我防卫方式而闻名——当受到威胁时，它们会迅速蜷缩成一个“刺球”，以抵御捕食者的攻击。这一行为看似简单明了，但实际上隐藏着一个长期困扰科学家们的谜团：为什么刺猬会选择这种方式来保护自己？

要理解这个问题，我们需要从刺猬的生态习性和身体结构入手。刺猬是一种小型哺乳动物，分布范围包括欧洲至日本西部以及加拿大东部至美国东部及巴哈马西部及巴哈马东部至中国西部及马来西亚西部西部及马来西亚东部西部西部及加拿大东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部东部