Cichlids and stingrays(慈鲷和黄貂鱼) can perform simple plus...
根据第二段This fact has been known for some time that Cichlids and stingrays can precisely detect small quantities without counting.(一段时间以来,人们就知道慈鲷和黄貂鱼可以精确地检测到少量而不需要计数。)可知,在进行研究之前人们早就知道慈鲷和黄貂鱼不需要数就能精确地识别较小...