Talk:Passive electrolocation in fish

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Detecting Earth's magnetic field[edit]

"Electrolocating fish use this ability to detect prey, locate other fish, avoid predators, and navigate by the Earth's magnetic field." WTF? Magnetic field? Are you really sure? As far as I know in electric fish such as sharks passive electrolocation works by picking up the electric signals given off by another fish's muscle contractions, while in freshwater electric fishes such as Mormyrids and Gymnotiforms active electrolocation works by setting up an electrostatic field and perceiving any disturbances of it, as happens when another fish swims through it. These things have nothing to do with Earth's magnetic field (other than they're in general & very broadly part of the grand phenomenon of electromagnetism). Meanwhile some kinds of migratory birds - that have no electroreceptive organs - are theorized to navigate by the Earth's magnetic field. What is the source for this article's statement about electric fish using Earth's magnetic field? And how in the world would something so large as Earth's magnetic field serve the fish locally in navigating through the streams and even small swamps (practically puddles) they often live in? 2001:569:7F18:8300:4D52:7273:779C:1989 (talk) 17:09, 20 November 2019 (UTC)[reply]

Thanks for the observation. Firstly, the statement is too definite: it's a hypothesis, as the rest of the article makes clear, so I've added "perhaps". Secondly, the purpose of a lead section in Wikipedia is to summarize the rest of the article, which this correctly does; a paragraph discusses a paper by Kalmijn (1974) which notes that when a sharkswims through the Earth's field it sets up a voltage gradient that could allow it to sense the Earth's field and hence to navigate by it. The general answer to your question is, it should never be an editor's opinion: it should always be the opinion of a reliable source cited in the body of the article. Chiswick Chap (talk) 17:26, 20 November 2019 (UTC)[reply]

Active vs passive electrolocation - reorganisation needed[edit]

Despite the article's title, it actually discusses active electrolocation in weakly electric fish, in a lengthy section that alternates between active and passive. This overlaps largely with Electroreception, Electric organ (biology), and with Electric fish, so some rewriting, reorganisation, or merging will be needed. Chiswick Chap (talk) 11:38, 3 April 2022 (UTC)[reply]