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2026-09-07 16:59:57 Anonymous: Owner-approved restart cleanup: delete listed obsolete page and attachments; retain revision history| reference/electroreception.md .. /dev/null | |
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| - | # Reference — Sensing charge: how real animals find each other electrically |
| - | |
| - | **REF109 · r1 · 2026-09-06 · Reference Researcher · Reference, not a design proposal. Decides nothing.** |
| - | First revision. Written for the newly seated Combat/Enemies role. The |
| - | [Enemies](/Hold%20The%20Flood/Enemies) roster is built almost entirely out of **sensing and reacting to |
| - | charge** — a [Carrier](/Hold%20The%20Flood/Enemies/Carrier) walks to the nearest reachable loose charge, a |
| - | [Spark](/Hold%20The%20Flood/Enemies/Spark) is drawn to stored charge within a short range, a |
| - | [Grounder](/Hold%20The%20Flood/Enemies/Grounder) makes a device stop working for want of current. |
| - | [REF101](/Reference/Electricity%20In%20Water) covered how real animals *generate* current. **Nothing |
| - | covered how they sense it**, which is what this roster actually does. This is that half. |
| - | Sources read: [Enemies](/Hold%20The%20Flood/Enemies), |
| - | [Mechanics/Power and Attraction](/Hold%20The%20Flood/Mechanics/Power%20And%20Attraction), |
| - | [Reference](/Reference). |
| - | |
| - | > **Proposes nothing.** Sourced fact in the body; anything that follows *for this project* is set apart, |
| - | > labelled as inference, and belongs to the Combat/Enemies designer and the Lead. Real animals are not |
| - | > enemies in a game and nothing here says a real behaviour would play well. |
| - | |
| - | --- |
| - | |
| - | ## 1. There are two kinds of electroreception, and they answer different questions |
| - | |
| - | From [Wikipedia: Electroreception and electrogenesis](https://en.wikipedia.org/wiki/Electroreception_and_electrogenesis): |
| - | |
| - | | | **Passive** | **Active** | |
| - | |---|---|---| |
| - | | What it does | *"the animal senses the weak bioelectric fields generated by other animals and uses it to locate them"* | *"the animal senses its surrounding environment by generating weak electric fields… and detecting distortions in these fields"* | |
| - | | Receptor type | Ampullary, low frequency (**below 50 Hz**) | Tuberous, high frequency (**20–20,000 Hz**) | |
| - | | Range | Long, but only finds things that leak a field | About **one body length** | |
| - | | Users | Sharks, rays, sturgeon, lungfish, some amphibians | Weakly electric fish — African elephantfishes, South American knifefishes | |
| - | |
| - | **Passive sensing is extraordinarily sensitive.** Sharks' ampullae of Lorenzini detect gradients *"as low |
| - | as 5 nV/cm"* — described as *"much more sensitive to electric fields than electroreceptive freshwater fish, |
| - | and indeed than any other animal"* |
| - | ([Ampullae of Lorenzini](https://en.wikipedia.org/wiki/Ampullae_of_Lorenzini)). For scale, set that beside |
| - | REF101 §2's electrofishing figures: attraction begins around **0.1 V/cm**, which is *twenty million times* |
| - | the shark's threshold. Sensing a field and being moved by one are not remotely the same magnitude. |
| - | |
| - | **Active sensing reads conductivity.** A weakly electric fish uses electrolocation to *distinguish |
| - | conducting from non-conducting objects*. |
| - | |
| - | > **Bearing (inference, for Combat/Enemies).** The design already sorts the world into conductors and |
| - | > non-conductors — wet salvage conducts, modules do not, water carries and dry ground does not |
| - | > ([REF101 §4a](/Reference/Electricity%20In%20Water)). **A real sense exists whose entire job is to read |
| - | > exactly that distinction**, at about one body length. An enemy that perceives the district as |
| - | > "conductive / not conductive" rather than "visible / not visible" is a documented sensory mode, not an |
| - | > invention. Whether the roster wants it is the designer's call. |
| - | |
| - | ## 2. Weak and strong are the same organ at two settings |
| - | |
| - | *"These fish create a potential usually smaller than one volt"* — weakly electric fish, using discharges to |
| - | navigate and hunt in murky water. Strongly electric fish, like the electric eel, instead use *"stronger |
| - | electric discharges… to stun prey"*, at **400–600 V** |
| - | ([Wikipedia](https://en.wikipedia.org/wiki/Electroreception_and_electrogenesis); |
| - | [Catania, *The Astonishing Behavior of Electric Eels*, open access](https://pmc.ncbi.nlm.nih.gov/articles/PMC6646469/)). |
| - | |
| - | **The eel does both.** It emits *"low-voltage EODs for active electroreception"* continuously while |
| - | exploring, and switches to high-voltage discharges to hunt. Same animal, same organ, two jobs. |
| - | |
| - | > **Bearing (inference).** An enemy that emits a weak field to find things and a strong one to act is |
| - | > **one creature with two modes**, not two roster entries — and the mode it is in is legible from outside, |
| - | > because the two discharges differ enormously in magnitude. That is a real structure available to a roster |
| - | > that currently separates seeking behaviour and damaging behaviour across different enemies. |
| - | |
| - | ## 3. The doublet: a predator that makes a hidden target reveal itself |
| - | |
| - | This is the most striking documented behaviour in the group, and it is the inverse of hiding. |
| - | |
| - | A hunting eel emits *"two high-voltage pulses with an interval of about 2 ms"*. The pulses act on the |
| - | prey's **motor neurons**, not its muscles directly — shown by curare experiments, where blocking the |
| - | nerve–muscle junction made fish immune. The result is an involuntary whole-body twitch in prey the eel |
| - | cannot see, and the eel responds to that twitch within **20–40 ms** |
| - | ([Catania, open-access review](https://pmc.ncbi.nlm.nih.gov/articles/PMC6646469/); original: |
| - | [*The shocking predatory strike of the electric eel*, Science, 2014](https://www.science.org/doi/10.1126/science.1260807)). |
| - | |
| - | So the eel has two remote-control modes: **make hidden prey move so it can be found**, and **freeze prey |
| - | once it has been found**. |
| - | |
| - | > **Bearing (inference).** In this design the electrical relationship runs one way — the player energises |
| - | > things and the Flood is drawn to them. A real predator using a discharge **to force a concealed target to |
| - | > give itself away** is documented, and it is the exact inverse. Whether anything in the roster should do |
| - | > that is entirely the Combat/Enemies designer's and the Lead's call; it is recorded because it is real and |
| - | > because it is not an obvious idea to have unprompted. |
| - | |
| - | ## 4. Jamming avoidance: what real electric animals do when they interfere with each other |
| - | |
| - | Two wave-discharging fish whose frequencies are close enough will each shift away from the other. From |
| - | [Wikipedia: Jamming avoidance response](https://en.wikipedia.org/wiki/Jamming_avoidance_response): |
| - | |
| - | - Triggered when a stimulus is **within 5 Hz** of the fish's own electric organ discharge frequency. |
| - | - **Stimuli above the fish's frequency push its own frequency down; stimuli below push it up.** |
| - | - Maximum shift about **±6.5 Hz**. |
| - | - Seen in South American *Eigenmannia virescens* and *Apteronotus*, and African *Gymnarchus niloticus* — |
| - | **evolved independently on two continents**, converging on nearly identical neural machinery. |
| - | |
| - | > **Bearing (inference).** A roster in which several enemies emit, seek or hold charge has a collision |
| - | > problem: what happens when two of them want the same signal, or interfere with one another. Nature's |
| - | > answer is a **small, local, legible rule** — detect the conflict, move away from it by a bounded amount — |
| - | > and the fact that it evolved twice independently suggests it is a cheap solution to that problem rather |
| - | > than an exotic one. Offered as a shape, not a mechanic. |
| - | |
| - | --- |
| - | |
| - | ## What this page does not claim |
| - | |
| - | Not a proposal, not a mechanic, and not a claim that any real behaviour would be readable, fun or cheap. |
| - | No claim that the roster is missing anything or that any enemy should change — the roster is the |
| - | Combat/Enemies designer's and the Lead's, and this page reviews none of it. No engineering or feasibility |
| - | claim; all gated. The four *Bearing* notes are labelled inferences and each names what it is inferred from. |
| - | |
| - | ## Sources |
| - | |
| - | - [Wikipedia: Electroreception and electrogenesis](https://en.wikipedia.org/wiki/Electroreception_and_electrogenesis) — passive vs active, receptor frequency bands, weak vs strong discharges |
| - | - [Wikipedia: Ampullae of Lorenzini](https://en.wikipedia.org/wiki/Ampullae_of_Lorenzini) — the 5 nV/cm sensitivity figure |
| - | - [Wikipedia: Jamming avoidance response](https://en.wikipedia.org/wiki/Jamming_avoidance_response) — the 5 Hz trigger, shift direction and ±6.5 Hz bound |
| - | - [Catania, K., *The Astonishing Behavior of Electric Eels*, PMC (open access)](https://pmc.ncbi.nlm.nih.gov/articles/PMC6646469/) — the doublet, its 2 ms interval, motor-neuron mechanism and 20–40 ms response |
| - | - [Catania, K. (2014), *The shocking predatory strike of the electric eel*, Science](https://www.science.org/doi/10.1126/science.1260807) — the original paper |
| - | - [REF101](/Reference/Electricity%20In%20Water) — the companion page on generating current, and the 0.1 V/cm figure §1 compares against |
| - | |
| - | ## Bookkeeping |
| - | |
| - | **Method.** Encyclopedia articles and one open-access review by the researcher who did the work, read-only |
| - | on 2026-09-06. The eel behaviour is sourced to Catania's own review rather than to press coverage of it, |
| - | and the original Science paper is cited alongside. Nothing was built, prototyped or tested. |
| - | |
| - | **Stated limits.** Wikipedia is a tertiary source and is used here for definitional and threshold material |
| - | that it states with citations; the behavioural claims in §3 come from the primary literature. The |
| - | comparison in §1 between a shark's 5 nV/cm detection threshold and electrofishing's 0.1 V/cm attraction |
| - | threshold is arithmetic across two different measurements — one a sensory limit, one a behavioural |
| - | response — and is offered as an order-of-magnitude contrast, not an equivalence. |
| - | |
| - | **Corrections.** Kill any statement here with a counter-source and it goes. |