--- title: The twilight zone: barreleyes, lanternfish and the biggest daily journey on Earth — a lesson of Mova's school · trees and pragmatics description: «The twilight zone: barreleyes, lanternfish and the biggest daily journey on Earth», a lesson of the biology course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Dive down and the light fades like evening: below about two hundred metres it is a dim b --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/) / The twilight zone: barreleyes, lantern… # The twilight zone: barreleyes, lanternfish and the biggest daily journey on Earth Lesson 175 of the biology course of Mova's primary school: 17 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/0/) — Dive down and the light fades like evening: below about two hundred metres it is a dim blue twilight, and below about a thousand metres sunlight is gone completely. - [1](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/1/) — In this twilight zone many animals make their own light, with rows of tiny lamps on their bellies, glowing clouds they squirt at enemies, or flashes like a torch switched on and off. - [2](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/2/) — 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 many that ship sonar (which measures depth by sending sound down and timing the echo) once mistook them for the sea floor rising. - [3](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/3/) — Think of it as the whole town getting in a lift every evening to eat on the top floor and riding back down before sunrise: it is the biggest journey animals make anywhere on Earth, every single day. - [4](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/4/) — Sunlight gets weaker as you go deeper; below about two hundred metres it is very dim, and below about a thousand metres there is no sunlight at all. - [5](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/5/) — The barreleye fish has a clear dome on its head, and its green eyes look up through it; its see-through head was only filmed alive in 2009, because nets used to destroy it. - [6](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/6/) — Lanternfish have light organs called photophores along their bodies, and they are among the most common fish on Earth; only the tiny bristlemouths may be more numerous. - [7](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/7/) — Huge numbers of animals swim up from the deep at night to feed near the surface and go back down at dawn, and this daily migration is the biggest movement of animals on Earth. - [8](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/8/) — The animals rise only at night because darkness hides them from hunters that find food by sight near the surface. - [9](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/9/) — Lights on the belly match the faint light coming from above, so a hunter looking up from below cannot see the animal's dark shape. - [10](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/10/) — Hatchetfish have thin silver bodies, lights on their bellies, and eyes that point upwards to spot food falling from above. - [11](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/11/) — Comb jellies have rows of tiny beating hairs that break light into rainbow colours; they are not true jellyfish and have no stinging cells. - [12](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/12/) — Some deep-sea shrimp squirt a glowing cloud to confuse a hunter, a little like squid ink but made of light. - [13](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/13/) — 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 light that most other animals cannot see. - [14](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/14/) — 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. - [15](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/15/) — 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. - [16](https://md.mova.elamur.ai/free/en/corpora/school/biology/175-the-twilight-zone-barreleyes-lanternfish-and-the-biggest-daily-journey-on-earth/16/) — 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. - ← previous: [Reef giants and wanderers: whale sharks, mantas, dugongs and sea turtles](https://md.mova.elamur.ai/free/en/corpora/school/biology/174-reef-giants-and-wanderers-whale-sharks-mantas-dugongs-and-sea-turtles/) - next →: [The deep dark: anglerfish, giant squid, blobfish and whale falls](https://md.mova.elamur.ai/free/en/corpora/school/biology/176-the-deep-dark-anglerfish-giant-squid-blobfish-and-whale-falls/) - ↑ back to [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/)