蛇， 19个成员中的任何一个爬行动物蛇科(蛇亚目，鳞状目)，没有四肢、声音、外耳或眼睑，只有一个有功能的肺和细长的身体。目前已知的蛇大约有2900种，大多数生活在热带地区。它们的皮肤上覆盖着鳞片。他们有很好的视力，他们不断地用舌头品尝周围的空气。虽然它们没有声音，却能发出嘶嘶声。大多数生活在地面上，但有些是树栖或水生的，还有一些是穴居动物。它们通过肌肉收缩和腹部细长的鳞片来移动。它们将70%的时间集中在追踪、捕捉和消化活的猎物上。它们下颚和身体的构造使它们能够整个吞下大型猎物。因为他们是变温动物(冷血动物)，一顿饭通常可以维持他们几个星期。 Mating and laying eggs or bearing live young are brief seasonal activities. About one-tenth of snake species are venomous; some can kill humans with their bite. Others kill their prey by constriction or simply ingesting. Species range from less than 5 in. (12 cm) to over 30 ft (9 m) long. Snakes grow continuously throughout their lives, shedding their outgrown skin at each growth increment. They are found worldwide, but few species are found on islands or in regions with long winters.
