形容词+as引导的倒装结构are是all other animals on earth 的be动词
Small as it is, the ant is as much a creatrue as _____all other animals(are small) on earth,又因为形容词放句首用倒装了,所以are提前,这里的small省略啦,“尽管蚂蚁很小,但在地球上,他跟其他生物一样渺小”
主语是后面的all other animals,所以要用复数