---
title: The twilight zone: barreleyes, lanternfish and the biggest daily jou… — how Mova does on the tests · Biology
description: Lesson 175 of the biology course of Mova's primary school: 6 of 11 tests right, exam 2 of 4, every question with the options, the student's choice, the right answer and why it chose.
---

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# The twilight zone: barreleyes, lanternfish and the biggest daily journey on Earth

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**Tests:** 6 of 11 right · **Exam:** 2 of 4 right · **Kind:** ★ · **Understood:** 12 of 15 · **Run:** 2026-10-18, commit `f3c23ea72`

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Lesson 175 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/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/).

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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/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/).

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### Test 1 · ★ · right ✓ {#t1}

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«sonar says the sea floor came up 300 metres at night wtf» What is really happening?

- **1.** The sonar is always broken at night — no support
- **2.** The sea is getting shallower forever — no support
- **3.** Huge crowds of animals are swimming up to feed in the dark — **← Mova's choice** · **✓ the right answer** · score 9
- **4.** The sea floor really moves up every night and back down by day — score 0

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**Why:** It took the question to ask what happens next. It chose option 3 with score 9, against 0 for the next best. Its support: lesson 175, line 3: «Every night, when it is dark above, huge crowds of fish, shrimp and squid swim up hundreds of metres to feed near the surface and sink back down at dawn, so ma…», reached through the same lesson line as the sentence the question matched. What matched: the same action «swim up» (+4); the same doer «huge crowds» (+3); its «because» matches the remembered cause (+2). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/t1/)

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### Test 2 · ★ · wrong ✗ {#t2}

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Why do so many animals swim up only at night and not by day?

- **1.** The surface water is colder by day — no support
- **2.** Sunlight burns them in seconds — **← Mova's choice** · score 4
- **3.** In the dark it is harder for hunters near the surface to see them — **✓ the right answer** · score 3
- **4.** They cannot swim during the day, so they lie still on the bottom till dark — score 2

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**Why:** It took the question to ask why something happens (its cause). It chose option 2 with score 4, against 3 for the next best. Its support: lesson 19, line 15: «A mirror layer at the back of a tiger's eye bounces light back through it, so tigers see far better than us at night and their eyes shine in headlights.», reached through the cause of the sentence the question matched. What matched: the same thing acted on «light» (+4); a different action (counts against) (+2). Against it: a different doer (counts against) (-2). The right option, 3, scored 3. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/t2/)

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### Test 3 · ★ · wrong ✗ {#t3}

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«3 cockeyed squids, how many eyes altogether, and how many big ones»

- **1.** 3 eyes, 3 big — **← Mova's choice** · score 6
- **2.** 4 eyes, 2 big — score 6
- **3.** 6 eyes, 3 big — **✓ the right answer** · score 6
- **4.** 6 eyes, 6 big — no support

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**Why:** It took the question to ask which statement is true. It chose option 1 with score 6, tied with another option at 6 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 175, line 17: «The cockeyed squid has one big eye that looks up and one small eye that looks down, and it swims tilted to keep each eye pointing the right way.», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «one big eye» (+3); the same property (+3). The right option, 3, scored 6. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/t3/)

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### Test 4 · ★ · right ✓ {#t4}

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A red shrimp is lit by a white lamp on a submarine and looks bright red. Why is it hard to see in its own home?

- **1.** It lives inside rocks — no support
- **2.** Fish there cannot see at all — no support
- **3.** No red light reaches the deep, so it looks black there — **← Mova's choice** · **✓ the right answer** · score 6
- **4.** It turns blue when the lamp goes off — no support

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**Why:** It took the question to ask why something happens (its cause). It chose option 3 with score 6, the only option with support. Its support: lesson 175, line 14: «Many deep-sea animals are red or black, because red light does not reach the deep, so a red animal looks black and is hard to see; some deep fish even make red…», reached through the cause of the sentence the question matched. What matched: the same action «reach» (+4); the same doer «red light» (+4); the same thing acted on «deep» (+4). Against it: one says «not», the other does not (counts against) (-6). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/t4/)

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### Test 5 · ★ · wrong ✗ {#t5}

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«that rainbow jellyfish thing is gonna sting me, run» What is right?

- **1.** Yes, it shocks with electricity — no support
- **2.** It is a comb jelly, which has no stinging cells — **✓ the right answer** · score 4
- **3.** It is a true jellyfish like all the others — no support
- **4.** Yes, rainbow colours always mean it is very poisonous — **← Mova's choice** · score 5

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**Why:** It took the question to ask which statement is true. It chose option 4 with score 5, against 4 for the next best. Its support: lesson 173, line 4: «Bright colours on a reef often mean the opposite of hiding: a glowing sea slug or a lionfish with spread fins is saying keep away, I taste bad or I sting.», reached through the same lesson line as the sentence the question matched. What matched: the same action «mean» (+4); the same doer «bright colours» (+2). Against it: a different thing acted on (counts against) (-1). The right option, 2, scored 4. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/t5/)

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### Test 6 · ★ · wrong ✗ {#t6}

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In a cartoon a deep-sea fish switches on a torch held in its fin. What is the real version?

- **1.** Deep fish really carry little torches — score 4
- **2.** Deep fish use fire to see — score 4
- **3.** No animal can make its own light, it is all reflected from the moon — **← Mova's choice** · score 8
- **4.** Many deep animals make their own light with light organs — **✓ the right answer** · score 8

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**Why:** It took the question to ask what it is done to. It chose option 3 with score 8, tied with another option at 8 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 175, line 14: «Many deep-sea animals are red or black, because red light does not reach the deep, so a red animal looks black and is hard to see; some deep fish even make red…», reached through the same lesson line as the sentence the question matched. What matched: the same doer «most other animals» (+3); it fills the role the question asks for (+3); the same thing acted on «red light» (+2). The right option, 4, scored 8. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/t6/)

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### Test 7 · ★ · wrong ✗ {#t7}

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What would happen if a lanternfish turned off all its belly lights?

- **1.** Nothing, the lights are only for fun — **← Mova's choice** · no support
- **2.** A hunter below might see its dark shape against the faint light above — **✓ the right answer** · no support
- **3.** It would glow even more — no support
- **4.** It would sink to the bottom — no support

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**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/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/t7/)

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### Test 8 · ★ · right ✓ {#t8}

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«my mate says that long jelly thing is one animal» What is right?

- **1.** It is a piece of rope — no support
- **2.** It is a sea snake — no support
- **3.** A siphonophore is a chain of many tiny animals living together — **← Mova's choice** · **✓ the right answer** · score 7
- **4.** Yes, it is one huge jellyfish with a very long tail, like a kite — no support

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**Why:** It took the question to ask which statement is true. It chose option 3 with score 7, the only option with support. Its support: lesson 175, line 15: «A siphonophore looks like one long jellyfish but is a chain of many tiny animals living together, and some are longer than a blue whale.», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «chain» (+3); the same circumstance (+2); the same light verb (be, have, do, get, go) (+2). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/t8/)

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### Test 9 · ★ · right ✓ {#t9}

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«barreleye pics always looked rubbish, why» What is the reason?

- **1.** Nets destroyed its see-through head until it was filmed alive in 2009 — **← Mova's choice** · **✓ the right answer** · score 0
- **2.** It has no head — no support
- **3.** It is too fast to film — no support
- **4.** It only lives in fish tanks — no support

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**Why:** It took the question to ask why something happens (its cause). It chose option 1 with score 0, the only option with support. Its support: lesson 174, line 4: «To a turtle, a plastic bag drifting in the water can look just like a jellyfish, which is one reason rubbish in the sea is so dangerous.», reached through the option's own match among the sentences about the question's things. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/t9/)

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### Test 10 · ★ · right ✓ {#t10}

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A diver goes down and down and the water turns from blue to dark. At about what depth is there no sunlight at all?

- **1.** About a thousand metres — **← Mova's choice** · **✓ the right answer** · no support
- **2.** Only about fifty metres down — no support
- **3.** About ten thousand metres — no support
- **4.** Only about ten metres or so — no support

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**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/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/t10/)

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### Test 11 · ★ · right ✓ {#t11}

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«fangtooth can't shut its mouth, poor thing» What is right?

- **1.** Right, it never closes it — score 3
- **2.** It has no teeth at all — no support
- **3.** It can, because pockets in its head fit the long teeth — **← Mova's choice** · **✓ the right answer** · score 5
- **4.** It closes it by pulling out its teeth one by one and putting them back later — score 5

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**Why:** It took the question to ask which statement is true. It chose option 3 with score 5, tied with another option at 5 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 175, line 16: «The fangtooth has some of the biggest teeth for its size of any fish, so long that it has pockets in its head to fit them when it closes its mouth.», reached through a sentence linked to the one the question matched. What matched: the same action «fit» (+3); the same doer «fangtooth» (+3). Against it: a different thing acted on (counts against) (-1). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/t11/)

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### Exam question 1 · formal language · right ✓ {#e1}

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Identify the phenomenon which is acknowledged to constitute the largest movement of animals upon Earth.

- **1.** The migration of salmon up rivers — no support
- **2.** The seasonal migration of wildebeest — no support
- **3.** The annual flight of swallows to Africa — no support
- **4.** The nightly ascent and dawn descent of animals of the twilight zone — **← Mova's choice** · **✓ the right answer** · score 2

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**Why:** It took the question to ask which statement is true. It chose option 4 with score 2, the only option with support. Its support: lesson 171, line 2: «It looks empty and icy, but in spring tiny drifting plants turn the water green, tiny shrimp-like krill eat them, and the biggest animals that ever lived come…», reached through the option's own match among the sentences about the question's things. What matched: the same action «come» (+2). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/e1/)

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### Exam question 2 · formal language · right ✓ {#e2}

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Which of the following statements most accurately characterises the comb jelly?

- **1.** It is a true jellyfish of exceptional venom — score 1
- **2.** It produces rainbow colours by means of beating hairs and possesses no stinging cells — **← Mova's choice** · **✓ the right answer** · score 3
- **3.** It emits electric discharges to stun its prey — no support
- **4.** It is a species of fish with transparent skin — no support

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**Why:** It took the question to ask who or what does it. It chose option 2 with score 3, against 1 for the next best. Its support: lesson 175, line 12: «Comb jellies have rows of tiny beating hairs that break light into rainbow colours; they are not true jellyfish and have no stinging cells.», 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 (+2); the same doer «comb jellies» (+1). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/e2/)

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

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Ascertain the reason for which numerous animals of the deep sea are of red colouration.

- **1.** Such animals consume exclusively red food — **← Mova's choice** · score 3
- **2.** Red light does not penetrate to such depths, so that red bodies appear black — **✓ the right answer** · score 2
- **3.** The red pigment retains heat in cold water — no support
- **4.** Red colouration attracts prey from the surface — no support

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**Why:** It took the question to ask which statement is true. It chose option 1 with score 3, against 2 for the next best. Its support: lesson 110, line 15: «Old zoo animals get special care, like soft food and pain medicine for stiff joints.», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «special care» (+3). The right option, 2, scored 2. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/e3/)

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

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Select the response consistent with the established facts concerning the siphonophore.

- **1.** It is a variety of deep-sea eel — **← Mova's choice** · no support
- **2.** It is a species of marine plant — no support
- **3.** It is a single jellyfish of modest dimensions — no support
- **4.** It is a colonial organism composed of many small animals, some exceeding a blue whale in length — **✓ the right answer** · no support

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**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/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/e4/)

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- ← previous: [174. Reef giants and wanderers: whale sharks, mantas,…](https://md.mova.elamur.ai/free/en/school-run/biology/174-reef-giants-and-wanderers-whale-sharks-mantas-dugongs-and-sea-turtles/)
- next →: [176. The deep dark: anglerfish, giant squid, blobfish…](https://md.mova.elamur.ai/free/en/school-run/biology/176-the-deep-dark-anglerfish-giant-squid-blobfish-and-whale-falls/)
- ↑ back to [Biology](https://md.mova.elamur.ai/free/en/school-run/biology/)