---
title: Electric senses: electric eels, sharks, the platypus bill and charge… — how Mova does on the tests · Biology
description: Lesson 231 of the biology course of Mova's primary school: 5 of 11 tests right, exam 0 of 4, every question with the options, the student's choice, the right answer and why it chose.
---

<!-- md -->
[Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/school-run/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/)

<!-- crumbs -->
[home](https://md.mova.elamur.ai/free/en/) / [at school](https://md.mova.elamur.ai/free/en/school-run/) / [Biology](https://md.mova.elamur.ai/free/en/school-run/biology/) / 231

# Electric senses: electric eels, sharks, the platypus bill and charged bees

<!-- .vintro -->
**Tests:** 5 of 11 right · **Exam:** 0 of 4 right · **Kind:** ★ · **Understood:** 10 of 15 · **Run:** 2026-10-18, commit `f3c23ea72`

<!-- .vabout -->
Lesson 231 of the biology course of Mova's primary school, as Mova's small model took its tests: it had read this lesson and the ones before it and learned from their exercises. Each test shows the options in the order the student saw them, its choice, the right answer, the score of every option and why it chose. The lesson itself, sentence by sentence with trees and pragmatics: [the lesson in the corpora](https://md.mova.elamur.ai/free/en/corpora/school/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/).

<!-- .vabout -->
Every question of this lesson and each of its options parsed by Mova, with trees and pragmatics: [the lesson's questions in the corpora](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/).

<!-- div qa ok -->

### Test 1 · ★ · right ✓ {#t1}

<!-- .q -->
«my teacher said people got nothing electric in them at all» What is right?

- **1.** Wrong, people can feel a shark from a mile away — no support
- **2.** We can't feel other animals' fields, but our heart and nerves run on electric signals — **← Mova's choice** · **✓ the right answer** · score 3
- **3.** Right, only fish and eels have electricity — no support
- **4.** Right, electricity only comes from sockets — no support

<!-- .why -->
**Why:** It took the question to ask which statement is true. It chose option 2 with score 3, the only option with support. Its support: lesson 231, line 16: «People cannot feel other animals' electric fields, but our hearts and brains work with electric signals that doctors measure with an ECG and an EEG.», reached through the option's own match among the sentences about the question's things. What matched: the same action «feel» (+2); the same thing acted on «electric fields» (+1). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/t1/)

<!-- /div -->

<!-- div qa no -->

### Test 2 · ★ · wrong ✗ {#t2}

<!-- .q -->
In a cartoon a cat touches a wire, his fur stands up, he goes black and walks off fine. What is true?

- **1.** Shocks only hurt if you are wet and cold — no support
- **2.** A real shock can stop the heart, so it is dangerous, not funny — **✓ the right answer** · no support
- **3.** Cats cannot be hurt by electricity, because their fur protects them like rubber — score 1
- **4.** Real shocks only make fur fluffy — **← Mova's choice** · score 3

<!-- .why -->
**Why:** It took the question to ask which statement is true. It chose option 4 with score 3, against 1 for the next best. Its support: lesson 169, line 11: «Polar bear skin is black and its fur is made of see-through hollow hairs that look white because they scatter light.», reached through the option's own match among the sentences about the question's things. What matched: the same action «make» (+2); the same thing acted on «fur» (+1). The right option, 2, found no support in what it remembers. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/t2/)

<!-- /div -->

<!-- div qa no -->

### Test 3 · ★ · wrong ✗ {#t3}

<!-- .q -->
«baby eel in the zoo, tiny, can't do nothing yeah?» What does the keeper mean when he warns you?

- **1.** Baby eels have no electric cells yet — score 2
- **2.** Baby eels give shocks only to other baby eels — **← Mova's choice** · score 11
- **3.** Baby eels only bite — score 2
- **4.** Even young electric eels can give a tingle — **✓ the right answer** · score 11

<!-- .why -->
**Why:** It took the question to ask who or what does it. It chose option 2 with score 11, tied with another option at 11 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 231, line 6: «Electric eels can give shocks of several hundred volts, about 600 or even more, more than twice the voltage of a home socket in Britain.», reached through the option's own match among the sentences about the question's things. What matched: it fills the role the question asks for (+4); the same doer «electric eels» (+3); the same action «give» (+2); the same thing acted on «shocks» (+2). The right option, 4, scored 11. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/t3/)

<!-- /div -->

<!-- div qa ok -->

### Test 4 · ★ · right ✓ {#t4}

<!-- .q -->
What would happen if a hungry shark lost the jelly pores on its snout?

- **1.** It could not swim straight any more, only in circles — score 3
- **2.** It would stop needing food for the rest of its life — score 3
- **3.** It would struggle to find buried fish — **← Mova's choice** · **✓ the right answer** · score 10
- **4.** It would go completely blind in both eyes — score 3

<!-- .why -->
**Why:** It took the question to ask what happens next. It chose option 3 with score 10, against 3 for the next best. Its support: lesson 28, line 3: «Sharks have senses you don't: pores on the snout, the ampullae of Lorenzini, feel the faint electricity of a fish's muscles, so a shark can find a fish hiding…», reached through the same lesson line as the sentence the question matched. What matched: the same action «find» (+4); the same doer «shark» (+3); the same thing acted on «fish» (+3). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/t4/)

<!-- /div -->

<!-- div qa ok -->

### Test 5 · ★ · right ✓ {#t5}

<!-- .q -->
A hammerhead sweeps its head over the sand like a boy with a metal detector on the beach. What is it looking for?

- **1.** Shiny coins dropped by careless divers — no support
- **2.** Stingrays hidden under the sand — **← Mova's choice** · **✓ the right answer** · score 10
- **3.** Its own teeth that fell out last week — no support
- **4.** Patches of warm water near the bottom — no support

<!-- .why -->
**Why:** It took the question to ask a circumstance (with what, when, how). It chose option 2 with score 10, the only option with support. Its support: lesson 231, line 10: «A hammerhead shark's wide head spreads its electric sensors over a wider strip of sea floor, like a metal detector sweeping a beach, as it hunts stingrays hidd…», reached through the same lesson line as the sentence the question matched. What matched: the same action «hide» (+4); the same thing acted on «stingrays» (+3); the same place «sand» (+3). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/t5/)

<!-- /div -->

<!-- div qa no -->

### Test 6 · ★ · wrong ✗ {#t6}

<!-- .q -->
Count them: 3 platypuses dive in a creek. How many bills and how many legs?

- **1.** 3 bills and 8 legs — **← Mova's choice** · no support
- **2.** 3 bills and 12 legs — **✓ the right answer** · no support
- **3.** 3 bills and 6 legs — no support
- **4.** 6 bills and 12 legs — no support

<!-- .why -->
**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/t6/)

<!-- /div -->

<!-- div qa no -->

### Test 7 · ★ · wrong ✗ {#t7}

<!-- .q -->
«crap, eel just lit up the bulb on the glass, how's a fish doin that» What is the best answer?

- **1.** It rubbed itself on the glass — **← Mova's choice** · no support
- **2.** The keeper hid a switch in the tank and pressed it — no support
- **3.** It swallowed the bulb's batteries — no support
- **4.** Its body is packed with cells that act like stacked batteries — **✓ the right answer** · no support

<!-- .why -->
**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/t7/)

<!-- /div -->

<!-- div qa ok -->

### Test 8 · ★ · right ✓ {#t8}

<!-- .q -->
Why can an elephantnose fish find worms in a river so muddy that no one could see?

- **1.** It has extra big eyes — score 4
- **2.** It follows the light of glow-worms — score 1
- **3.** It only ever eats in clear water — score 2
- **4.** It feels changes in the electric field it makes around itself — **← Mova's choice** · **✓ the right answer** · score 5

<!-- .why -->
**Why:** It took the question to ask why something happens (its cause). It chose option 4 with score 5, against 4 for the next best. Its support: lesson 231, line 12: «Elephantnose fish make a weak electric field around themselves and read it with their long chins to find food in dark, muddy African rivers.», reached through the same lesson line as the sentence the question matched. What matched: the same action «make» (+4); the same doer «elephantnose fish» (+1). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/t8/)

<!-- /div -->

<!-- div qa no -->

### Test 9 · ★ · wrong ✗ {#t9}

<!-- .q -->
In a film an electric ray lies flat on the sand. A diver steps near it. What could happen?

- **1.** The ray could give a strong shock to defend itself — **✓ the right answer** · score 1
- **2.** Nothing, rays are made of jelly — no support
- **3.** The ray would light up like a lamp — **← Mova's choice** · score 3
- **4.** The ray would swim up off the sand and hug the diver — score 3

<!-- .why -->
**Why:** It took the question to ask what happens next. It chose option 3 with score 3, tied with another option at 3 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 231, line 13: «Electric rays lie flat on the sand and can stun fish with shocks of up to about 200 volts; Roman doctors once used them to numb pain.», reached through what followed the sentence the question matched. What matched: the same doer «electric rays» (+3). The right option, 1, scored 1. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/t9/)

<!-- /div -->

<!-- div qa ok -->

### Test 10 · ★ · right ✓ {#t10}

<!-- .q -->
«we got 2 bees, 1 flower, first bee leaves, second bee won't land. weird?» What may be going on?

- **1.** The first bee locked the flower — score 7
- **2.** The flower's charge changed after the first visit, so it may be empty — **← Mova's choice** · **✓ the right answer** · score 11
- **3.** Bees only land on flowers nobody has touched for a year — score 5
- **4.** The second bee is scared of yellow — score 5

<!-- .why -->
**Why:** It took the question to ask who or what does it. It chose option 2 with score 11, against 7 for the next best. Its support: lesson 231, line 14: «A bumblebee can feel a flower's weak electric charge, which changes for a while after another bee visits, so the bee may skip a flower that was just emptied.», reached through a sentence linked to the one the question matched. What matched: the same action «change» (+6); it fills the role the question asks for (+3); the same doer «weak electric charge» (+2). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/t10/)

<!-- /div -->

<!-- div qa no -->

### Test 11 · ★ · wrong ✗ {#t11}

<!-- .q -->
Count them: 5 bumblebees sit on lavender. How many legs and how many wings?

- **1.** 20 legs and 10 wings — **← Mova's choice** · no support
- **2.** 30 legs and 10 wings — no support
- **3.** 30 legs and 20 wings — **✓ the right answer** · no support
- **4.** 40 legs and 20 wings — no support

<!-- .why -->
**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/t11/)

<!-- /div -->

<!-- div qa no -->

### Exam question 1 · formal language · wrong ✗ {#e1}

<!-- .q -->
Identify the principal function of the ampullae of Lorenzini in sharks.

- **1.** The regulation of the temperature of the blood — **← Mova's choice** · no support
- **2.** The reception of airborne sound — no support
- **3.** The production of electric discharges of sufficient strength to stun prey — no support
- **4.** The detection of weak electric fields produced by other organisms — **✓ the right answer** · no support

<!-- .why -->
**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/e1/)

<!-- /div -->

<!-- div qa no -->

### Exam question 2 · formal language · wrong ✗ {#e2}

<!-- .q -->
Select the response consistent with the established facts concerning the foraging of the platypus beneath the water.

- **1.** It locates prey solely by its sense of smell — no support
- **2.** It locates prey by means of electric and tactile receptors in its bill — **✓ the right answer** · no support
- **3.** It detects prey by echolocation — **← Mova's choice** · score 1
- **4.** It relies principally upon acute underwater vision — no support

<!-- .why -->
**Why:** It took the question to ask which statement is true. It chose option 3 with score 1, the only option with support. Its support: lesson 231, line 2: «We cannot feel these buzzes, but many water animals can. A shark gliding over the sand can feel the heartbeat of a fish hiding underneath, like you finding a f…», reached through the option's own match among the sentences about the question's things. What matched: the same action «find» (+2); the same thing acted on «friend» (+1). Against it: a different doer (counts against) (-2). The right option, 2, found no support in what it remembers. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/e2/)

<!-- /div -->

<!-- div qa no -->

### Exam question 3 · formal language · wrong ✗ {#e3}

<!-- .q -->
Which of the following statements most accurately characterises the taxonomic position of the electric eel?

- **1.** It is a true eel of the family of freshwater eels found in European rivers — **← Mova's choice** · no support
- **2.** It is a knifefish, more closely allied to catfishes than to true eels — **✓ the right answer** · no support
- **3.** It is an amphibian of riverine habitat — no support
- **4.** It is a species of shark — no support

<!-- .why -->
**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/e3/)

<!-- /div -->

<!-- div qa no -->

### Exam question 4 · formal language · wrong ✗ {#e4}

<!-- .q -->
Ascertain the reason for which electric senses occur predominantly among aquatic animals.

- **1.** Electric fields cannot be generated by any animal upon dry land — score 3
- **2.** Water conducts electricity far more effectively than air — **✓ the right answer** · score 5
- **3.** Light is entirely absent from all waters — **← Mova's choice** · score 7
- **4.** Aquatic animals possess no other senses — score 2

<!-- .why -->
**Why:** It took the question to ask which statement is true. It chose option 3 with score 7, against 5 for the next best. Its support: lesson 231, line 4: «Water carries electricity well, which is why almost all electric senses belong to animals that live or hunt in water; on land, bees are a rare surprise.», reached through the option's own match among the sentences about the question's things. What matched: the same place «water» (+4); the same doer «animals» (+3). The right option, 2, scored 5. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/231-electric-senses-eels-sharks-the-platypus-and-charged-bees/e4/)

<!-- /div -->

<!-- pn -->
- ← previous: [230. Echolocation in the sea and in people: dolphins,…](https://md.mova.elamur.ai/free/en/school-run/biology/230-echolocation-in-the-sea-and-in-people-dolphins-whales-swiftlets-and-clicking-humans/)
- next →: [232. Hidden senses: magnetic birds and turtles, ultra…](https://md.mova.elamur.ai/free/en/school-run/biology/232-hidden-senses-magnetic-birds-ultraviolet-bees-heat-seeing-snakes/)
- ↑ back to [Biology](https://md.mova.elamur.ai/free/en/school-run/biology/)