--- title: The aquarium: the shark tunnel and the rays — a lesson of Mova's school · trees and pragmatics description: «The aquarium: the shark tunnel and the rays», a lesson of the biology course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: In a big aquarium you can walk through a tunnel of thick clear acrylic, so the sea is all around you and sharks glide over you --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/) [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 aquarium: the shark tunnel and the… # The aquarium: the shark tunnel and the rays Lesson 91 of the biology course of Mova's primary school: 19 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/91-the-aquarium-the-shark-tunnel-and-the-rays/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/0/) — In a big aquarium you can walk through a tunnel of thick clear acrylic, so the sea is all around you and sharks glide over your head. - [1](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/1/) — The sharks swim past the smaller fish without snapping at them, because the keepers feed them full meals from a long pole and a full shark is not hunting. - [2](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/2/) — Sharks and rays are cousins: both have skeletons of cartilage, the bendy stuff in your ear, and a ray is really a shark flattened out for life on the sea floor. - [3](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/3/) — Look closely and you find surprises: shark skin made of tiny teeth, a shark egg case called a mermaid's purse, and a sawfish whose saw can feel electricity. - [4](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/4/) — Films like Jaws made people fear sharks, but the true numbers run the other way: people kill far more sharks than sharks ever kill people. - [5](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/5/) — Aquarium tunnels are made of acrylic many centimetres thick, strong enough to hold back millions of litres of water. - [6](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/6/) — Aquarium sharks are fed regular meals of fish, often from a long pole, and keepers record how much each one eats, so they mostly ignore their tankmates. - [7](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/7/) — The sand tiger shark looks fierce with its long jagged teeth, but it is slow and calm; the thin teeth are for gripping slippery fish, and it gulps air at the surface to help it float. - [8](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/8/) — Great white sharks, the sharks of Jaws, hunt fish and seals and are rarely kept in aquariums because they swim huge distances and many stopped eating or died in tanks. - [9](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/9/) — Sharks kill fewer than about ten people a year worldwide, while people kill tens of millions of sharks every year. - [10](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/10/) — Rays are flat relatives of sharks with cartilage skeletons; they hide in sand and eat shellfish and worms, and a stingray's barb on its tail is only for defence. - [11](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/11/) — In touch pools the rays' barbs are safely trimmed, and visitors stroke them gently with two fingers so the animals are not hurt. - [12](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/12/) — The manta ray is the biggest ray, with fins up to about 7 metres across, and it eats tiny floating plankton by swimming with its mouth open; plankton is everywhere in the sea, so filtering lots of it can feed a huge body. - [13](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/13/) — A sawfish is a ray with a long flat saw edged with tooth-like points; it swings the saw to stun fish, and the saw also feels the tiny electric signals of hidden prey. - [14](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/14/) — Sawfish are critically endangered, mainly because their saws tangle in fishing nets. - [15](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/15/) — Some sharks, like the nurse shark, can rest on the bottom and pump water over their gills, but others, like the great white, must keep swimming to breathe. - [16](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/16/) — Some sharks and skates lay eggs in tough cases called mermaid's purses, and the baby grows inside for months, fed by a yolk. - [17](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/17/) — Shark skin is covered in tiny tooth-like scales called denticles, which feel smooth one way and like sandpaper the other and help water slip past. - [18](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/18/) — The whale shark is the biggest fish of all, up to about 18 metres long, and it filters plankton and small fish; it is a shark, not a whale, because it breathes with gills and has a cartilage skeleton. - ← previous: [The aquarium: the coral reef tank](https://md.mova.elamur.ai/free/en/corpora/school/biology/90-aquarium-the-coral-reef-tank/) - next →: [The aquarium: jellyfish, octopuses, sea stars and the deep sea](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/) - ↑ back to [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/)