Department of Zoology, University of Melbourne, Parkville, Victoria, 3010, Australia.
J Exp Biol. 2010 Feb 15;213(4):651-7. doi: 10.1242/jeb.039073.
The five sensory modalities of humans are also found in a wide range of invertebrates. Other vertebrates have evolved additional special senses, such as the magnetic sense, which are also found in some invertebrates. However, there remain a few sensory abilities that curiously appear to be found in either vertebrates or invertebrates, but not both. For example, electrosensitivity - the ability to detect electric fields in water - which should benefit vertebrates and invertebrates alike, is apparently only used by vertebrates. However, recent reports suggest that some invertebrates could have an electric sense. Here we examine that possibility further and demonstrate a behavioural threshold to low-level electrical fields in two freshwater invertebrates. The responses are not low enough for them to detect the Earth's magnetic field as some other electroreceptive species can do, but sufficiently low for them to use in navigation or prey and predator detection. This finding challenges the current view of the sensory world of aquatic invertebrates and has implications for the evolution of this ability.
人类的五种感官模式也存在于广泛的无脊椎动物中。其他脊椎动物已经进化出了额外的特殊感官，例如磁性感觉，这种感觉也存在于一些无脊椎动物中。然而，仍然有一些感觉能力似乎只存在于脊椎动物或无脊椎动物中，而不是两者都有。例如，电敏感性——检测水中电场的能力——这对脊椎动物和无脊椎动物都有好处，但显然只有脊椎动物使用。然而，最近的报告表明，一些无脊椎动物可能具有电感觉。在这里，我们进一步研究了这种可能性，并在两种淡水无脊椎动物中证明了对低水平电场的行为阈值。这些反应还不够低，无法像其他一些电感受器物种那样检测到地球磁场，但足以用于导航或猎物和捕食者的探测。这一发现挑战了水生无脊椎动物感觉世界的现有观点，并对这种能力的进化产生了影响。
