Biocenter Grindel and Zoological Museum, University of Hamburg, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany.
Proc Biol Sci. 2012 Feb 22;279(1729):663-8. doi: 10.1098/rspb.2011.1127. Epub 2011 Jul 27.
Passive electroreception is a widespread sense in fishes and amphibians, but in mammals this sensory ability has previously only been shown in monotremes. While the electroreceptors in fish and amphibians evolved from mechanosensory lateral line organs, those of monotremes are based on cutaneous glands innervated by trigeminal nerves. Electroreceptors evolved from other structures or in other taxa were unknown to date. Here we show that the hairless vibrissal crypts on the rostrum of the Guiana dolphin (Sotalia guianensis), structures originally associated with the mammalian whiskers, serve as electroreceptors. Histological investigations revealed that the vibrissal crypts possess a well-innervated ampullary structure reminiscent of ampullary electroreceptors in other species. Psychophysical experiments with a male Guiana dolphin determined a sensory detection threshold for weak electric fields of 4.6 µV cm(-1), which is comparable to the sensitivity of electroreceptors in platypuses. Our results show that electroreceptors can evolve from a mechanosensory organ that nearly all mammals possess and suggest the discovery of this kind of electroreception in more species, especially those with an aquatic or semi-aquatic lifestyle.
被动电感受是鱼类和两栖类中广泛存在的一种感觉方式，但在哺乳动物中，这种感觉能力以前只在单孔目动物中被发现过。鱼类和两栖类的电感受器是由机械感受的侧线器官进化而来的，而单孔目动物的电感受器则基于由三叉神经支配的皮肤腺。到目前为止，还不知道其他结构或其他分类群中的电感受器是如何进化而来的。在这里，我们表明，圭亚那海豚（Sotalia guianensis）喙上的无毛触须隐窝是电感受器，这些结构最初与哺乳动物的胡须有关。组织学研究表明，触须隐窝具有良好神经支配的壶腹结构，这让人联想到其他物种的壶腹电感受器。对一只雄性圭亚那海豚进行的心理物理学实验确定了对弱电场的感觉检测阈值为 4.6µV cm(-1)，这与鸭嘴兽的电感受器的灵敏度相当。我们的研究结果表明，电感受器可以从几乎所有哺乳动物都拥有的机械感觉器官进化而来，并表明在更多的物种中发现了这种电感受，特别是那些具有水生或半水生生活方式的物种。
