--- title: Vents and trenches: tubeworms, iron snails, the Challenger Deep and life without sunlight — a lesson of Mova's school · trees and pragmatics description: «Vents and trenches: tubeworms, iron snails, the Challenger Deep and life without sunlight», a lesson of the biology course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: On the dark sea floor there are cracks where water, heated by hot rock deep belo --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/biology/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/) [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/) / Vents and trenches: tubeworms, iron sn… # Vents and trenches: tubeworms, iron snails, the Challenger Deep and life without sunlight Lesson 177 of the biology course of Mova's primary school: 13 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/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/biology/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/0/) — On the dark sea floor there are cracks where water, heated by hot rock deep below, gushes out full of minerals, and when it meets the freezing sea the minerals turn into black smoke and build tall chimneys. - [1](https://md.mova.elamur.ai/free/en/corpora/school/biology/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/1/) — No sunlight ever reaches there, yet these hot vents are crowded with life: giant red-tipped tubeworms, hairy crabs, swarms of shrimp and even a snail wearing armour made of iron. - [2](https://md.mova.elamur.ai/free/en/corpora/school/biology/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/2/) — The secret is bacteria that make food from chemicals in the vent water instead of from sunlight, so the whole town lives on chemical food, like a kitchen run on a gas pipe instead of a sunny window. - [5](https://md.mova.elamur.ai/free/en/corpora/school/biology/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/5/) — Vent water can be hotter than three hundred degrees, but it does not boil because of the huge pressure of the deep sea. - [6](https://md.mova.elamur.ai/free/en/corpora/school/biology/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/6/) — Giant tubeworms have no mouth and no gut; bacteria living inside them make food from chemicals in the vent water, and the worms can grow over two metres long. - [8](https://md.mova.elamur.ai/free/en/corpora/school/biology/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/8/) — The scaly-foot snail has a shell and scales made of iron sulfide, the only animal known to build armour from it, which may protect it from crabs and other predators. - [9](https://md.mova.elamur.ai/free/en/corpora/school/biology/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/9/) — The Challenger Deep in the Mariana Trench is the deepest point of the ocean, nearly eleven kilometres down, and two men first reached it in 1960 in the submersible (a small deep-diving craft) Trieste. - [10](https://md.mova.elamur.ai/free/en/corpora/school/biology/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/10/) — Snailfish have soft bones and watery bodies, so the pressure does not crush them, and the deepest fish ever filmed was a snailfish at over eight kilometres. - [11](https://md.mova.elamur.ai/free/en/corpora/school/biology/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/11/) — Amphipods are small shrimp-like animals in the deepest trenches that eat dead stuff sinking from above, and scientists have found plastic inside some of them. - [12](https://md.mova.elamur.ai/free/en/corpora/school/biology/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/12/) — Before vents were found in 1977, scientists thought all life on Earth depended on sunlight; some scientists now think life on Earth may have started at vents, but nobody knows for sure. - [13](https://md.mova.elamur.ai/free/en/corpora/school/biology/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/13/) — Cold seeps are places where gas and oil leak from the sea floor, and bacteria there make food from the chemicals; some seep animals live for hundreds of years. - [14](https://md.mova.elamur.ai/free/en/corpora/school/biology/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/14/) — A deep-sea octopus was watched guarding her eggs for about four and a half years, the longest egg-guarding time known, because eggs grow very slowly in the cold. - [15](https://md.mova.elamur.ai/free/en/corpora/school/biology/177-vents-and-trenches-tubeworms-iron-snails-the-challenger-deep-and-life-without-sunlight/15/) — Vent shrimp crowd near the hot water but not too close, eat bacteria that grow on them, and have eye spots on their backs that may sense the dim glow of vents. - ← previous: [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/) - next →: [Mangroves: trees in salt water, mudskippers, archerfish and swimming tigers](https://md.mova.elamur.ai/free/en/corpora/school/biology/178-mangroves-trees-in-salt-water-mudskippers-archerfish-and-swimming-tigers/) - ↑ back to [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/)